CA2254528C - Treatment of ischemia reperfusion injury and treatment of cellular dysfunction including arrhythmia and heart failure subsequent to myocardial infarction - Google Patents

Abstract

Compositions and methods for treatment and prevention of ischemia-related conditions, such as ischemia reperfusion injury and cellular dysfunction, are disclosed.
The methods are directed to administering pharmaceutical compositions containing at least one compound derived from vitamin B6, such as pyridoxal-5'-phosphate, pyridoxine, pyridoxal, and pyridoxamine.

Description

TREATMENT OF ISCHEMIA REFERUSION INJURY AND TREATMENT
OF CELLULAR DYSFUNCTION INCLUDING AItMYTHMIA AND HEART
FAILURE SUBSEQUENT TO MYOCARDIAL INFARCTION
FIELD OF THE INVENTION
This invention relates to treating ischemia reperfusion injuries in different organs and to treating cellular dysfunction including arrhythmia and heart failure subsequent to myocardial infarction.
BACKGROUND
Ischemia is defined by an organ or a part of the body failing to receive a sufficient blood supply. An organ that is deprived of a blood supply is said to be hypoxic. An organ will become. hypoxic even when the blood supply temporarily ceases, such as during a surgical procedure or during temporary artery blockage. When blood flow resumes to an organ after temporary cessation, this is known as ischemic reperfusion of the organ. Ischemic reperfusion to an organ may lead to injury of the organ by producing structural and functional abnormalities in the tissue of the organ.
Conditions observed with ischemia reperfusion injury include neutrophil infiltration, hemorrhage, edema, and necrosis.

One example of an ischemia reperfusion injury is myocardial infarction.
Myocardial infarction arises from the interruption of blood supply to the myocardium (the muscular wall of the heart). This interruption of blood supply leads to the,;
development of an infarct, blood-deprived region of the myocardium and, ultirnately, to the loss of function of the myocardium or heart failure.

The ischemia reperfusion injury is believed to arise from the generation of excess oxidative free radicals by the blood as it reperfuses the ischemic organs and to disturbance in the cellular stores of adenosine triphosphate (ATP). For example, myocardial infarction is associated with a disturbance in ATP and the occurrence of intracellular calcium overload.

SUMMARY OF THE INVENTION
The present invention relates to the discovery that pyridoxal-5'-phosphate (PLP
and also called P-5P) can be used to treat ischemia reperfusion injuries in an organ and to treat arrhythmia and contractile dysfunction subsequent to myocardial infarction.
Pyridoxal-5'-phosphate, PLP, is, chemically, 3-hydroxy-2-methyl-5-[(phosphonooxy) methyl]-4-pyridine-carboxaldehyde, of chemical formula:

O OH

OH CHO

PLP is a derivative of vitamin B6 (pyridoxine hydrochloride) and has potent B6 activity. Mammals produce PLP by phosphorylating and oxidizing vitamin B6. The phosphorylation of vitamin B6 is accomplished by pyridoxal kinase. PLP can be chemically synthesized in a number of ways, for example, by the action of ATP
on pyridoxal, by the action of phosphorus oxychloride on pyridoxal in aqueous solution, and by phosphorylation of pyridoxamine with concentrated phosphoric acid followed by oxidation.

The biological role of PLP includes acting as a coenzyme and as an antagonist.
PLP is a coenzyme at the glycogen phosphorylase level (glycogenolysis) and at the transamination level in the malate aspartate shuttle (glycolysis and glycogenolysis).
Further, PLP is an antagonist of a purinergic receptor, thereby affecting ATP
binding.
To date, PLP has been therapeutically used as an enzyme cofactor vitamin.

The present invention includes methods and compositions for treating ischemia-related conditions. In one aspect, the invention includes a method for treating ischemia reperfusion injury and cellular dysfunction in mammals that includes administering to the mammal a therapeutic amount of a compound selected from the group consisting of pyridoxal-5'-phosphate, pyridoxine, pyridoxal, and pyridoxamine.

In another aspect, the invention is directed to a pharmaceutical composition that includes a pharmaceutically acceptable carrier and a therapeutic amount of a compound selected from the group consisting of pyridoxal-5'-phosphate, pyridoxine, pyridoxal, and pyridoxamine for treating ischemia reperfusion injury and cellular dysfunction.
DESCRIPTION OF THE INVENTION
The present invention provides compositions and methods for treatment of ischemia-related conditions, such as ischemia reperfusion injury and cellular dysfunction. The invention generally is directed to administering pharmaceutical compositions containing a therapeutic amount of at least one compound derived from vitamin B6.

In accordance with the present invention, it has been found that PLP can be used in the treatment of ischemia reperfusion injuries and cellular dysfunction.
Examples of cellular dysfunction include arrhythmia and heart dysfunction subsequent to myocardial infarction. "Treatment" and "treating" as used herein include preventing, inhibiting, alleviating, and healing the ischemia-related conditions or symptoms thereof affecting mammalian organs and tissues. For instance, a composition of the present invention can be administered prior to ischemia to prevent, inhibit, or protect against ischemia reperfusion injuries and cellular dysfunction of organs and tissues.
Alternatively, a composition of the invention can be administered during or following ischemia (including during or following reperfusion) to alleviate or heal ischemia reperfusion injuries and cellular dysfunction of organs and tissues.

Other pharmaceutical compounds derived from vitamin B6 suitable for treatment of ischemia-related conditions include pyridoxine, pyridoxal, and pyridoxamine. One skilled in the art would appreciate that these derivatives would have nearly identical effects as PLP after being adjusted for metabolic and molecular weight differences.

In one aspect, the invention is directed to a method of treating ischemia reperfusion injury and cellular dysfunction in mammals comprising administering to the mammal a therapeutic amount of a compound selected from the group consisting of pyridoxal-5'-phosphate, pyridoxine, pyridoxal, and pyridoxamine. Cellular dysfunction may include an arrhythmia of the heart or heart failure resulting from myocardial infarction. A "therapeutic amount" as used herein includes a prophylactic amount, for example, an amount effective for preventing or protecting against ischemia-related conditions, and amounts effective for alleviating or healing ischemia-related conditions.
Administering a therapeutic amount of a compound for treating ischemia reperfusion injury and cellular dysfunction preferably is in the range of about 1-50 mg/kg of a patient's body weight, more preferably in the range of about 5-25 mg/kg of a patient's body weight, per daily dose. The compound may be administered for periods of short and long duration. Although some individual situations may warrant to the contrary, short-term administration of doses larger than 25 mg/kg of a patient's body weight is preferred to long-term administration. For instance, as described in the Examples, the compound may be administered in an amount up to 50 mg/kg of a patient's body weight for a short term, for example, 21 days without noticeable side effects. In this same vein, when long-term administration (such as months or years) is required, the suggested dose should be no more than 25 mg/kg of a patient's body weight.

A therapeutic amount of the compound for treating ischemia-related conditions can be administered before, during, or following ischemia (including during or following reperfusion), as well as continually for some period spanning from pre- to post-ischemia. For example, the compound may be administered prior to heart procedures, including bypass surgery, thrombolysis, and angioplasty, and prior to any other procedures that require blood flow be interrupted and then resumed.
Additionally, the compound may be taken on a regular basis to protect against cellular dysfunction arising from arrhythmia and heart failure.

As an illustration, administration to a human of a pharmaceutical composition containing PLP will be described. When a human is presented for a heart procedure, for example, bypass surgery, thrombolysis, or angioplasty, or for a procedure requiring interruption of blood flow, an aqueous solution comprising PLP in a therapeutic amount can be given intravenously, immediately prior to surgery and then throughout a patient's hospitalization. Alternatively, the pharmaceutical composition comprising PLP
can be given immediately prior to surgery and then continuously for up to one week following surgery. After hospitalization, a human can be administered an enteral dose of PLP for a period determined suitable by a physician, usually, for example, not to exceed 8 to 12 months.
Similarly, a human may be administered an enteral dose of PLP beginning with the onset of symptoms of ischemia-related conditions through the surgical procedure.
Furthermore, a human at risk for arrhythmia or heart failure may be administered a regular enteral dose of PLP to protect against cellular dysfunction.
In a preferred aspect of the invention, a method of treating ischemia reperfusion injury and cellular dysfunction in mammals includes administering to the mammal a therapeutic amount of PLP for treating the ischemia reperfusion injury and cellular dysfunction. In another aspect, the compound administered may be pyridoxine, pyridoxal, or pyridoxamine.

In yet another aspect of the invention, a method of preventing or treating a particular cellular dysfunction known as arrhythmia of the heart in mammals includes administering to the mammal a therapeutic amount of a compound selected from the group consisting of pyridoxal-5'-phosphate, pyridoxine, pyridoxal, or pyridoxamine for treating arrhythmia of the heart. In still another aspect of the invention, the cellular dysfunction that is treated is heart failure resulting from myocardial infarction.

A pharmaceutical composition of the present invention is directed to a composition suitable for the treatment of ischemia reperfusion injury and cellular dysfunction. Examples of cellular dysfunction include arrhythmia of the heart and heart failure arising from myocardial infarction. The pharmaceutical composition comprises a pharmaceutically acceptable carrier and a compound selected from the group consisting of pyridoxal-5'-phosphate, pyridoxine, pyridoxal, and pyridoxamine.
A
pharmaceutically acceptable carrier includes, but is not limited to, physiological saline, ringers, phosphate buffered saline, and other carriers known in the art.
Pharmaceutical compositions may also include stabilizers, anti-oxidants, colorants, and diluents.
Pharmaceutically acceptable carriers and additives are chosen such that side effects from the pharmaceutical compound are minimized and the performance of the compound is not canceled or inhibited to such an extent that treatment is ineffective.
Preferably, the compound selected is PLP.

The pharmaceutical compositions may be administered enterally and parenterally. Parenteral administration includes subcutaneous, intramuscular, intradermal, intramammary, intravenous, and other administrative methods known in the art. Enteral administration includes solution, tablets, sustained release capsules, enteric coated capsules, and syrups. When administered, the pharmaceutical composition should be at or near body temperature.

Methods of preparing pharmaceutical compositions containing a pharmaceutically acceptable carrier and a therapeutic compound selected from PLP, pyridoxine, pyridoxal, and pyridoxamine are known to those of skill in the art. As an illustration, a method of preparing a pharmaceutical composition containing PLP will be described.

Generally, a PLP solution may be prepared by simply mixing PLP with a pharmaceutically acceptable solution, for example, buffered aqueous saline solution at an acidic or alkaline pH (because PLP is essentially insoluble in water, alcohol, and ether), at a temperature of at least room temperature and under sterile conditions.
Preferably, the PLP solution is prepared immediately prior to administration to the mammal. However, if the PLP solution is prepared at a time more than immediately prior to the administration to the mammal, the prepared solution should be stored under sterile, refrigerated conditions. Furthermore, because PLP is light sensitive, the PLP
solution should be stored in containers suitable for protecting the PLP
solution from the light, such as amber-colored vials or bottles.

Although it is not intended that this invention should be limited to any particular mechanism or theory of action, the following is offered as a tentative explanation for better understanding of the invention as a whole.

According to the vitamin B6 homocysteine theory, a relative deficiency of vitamin B6 leads to an accumulation of homocysteine. Homocysteine is an atherogenic amino acid. Homocysteine accumulation results in vascular endothelium damage, platelet function derangements, and arteriosclerosis. Vitamin B6 is known to help prevent the negative effects of homocysteine accumulation. Because PLP is the coenzyme required for catabolism of homocysteine, it has been suggested that vitamin B6's therapeutic ability is related to an increased formation of PLP. Thus, the beneficial effects of PLP in treating ischemia-related conditions may arise from the catabolism of homocysteine by PLP administered according to the present invention.
An alternative to the vitamin B6 homocysteine theory is the ATP theory. In response to ischemia, excess ATP is made available. Because ATP affects cardiomyocytes and the contraction of vascular smooth muscle, extracelluar ATP
exerts significant influence on cardiovascular function. For instance, ATP modulates ionic currents, calcium homeostasis, and excitation-contraction coupling in atrial and ventricular myocytes. We have shown that PLP depresses the ATP-induced increase in intracellular calcium. Thus, PLP may serve as an endogenous antagonist of ATP
receptor (P2x) and buffer the action of exogenously released ATP on cardiomyocytes and vascular myocytes.
It has been found, according to the present invention, that PLP, pyridoxine, pyridoxal, and pyridoxamine appropriately administered can have previously unexpected, highly beneficial effects on ischemia reperfusion injuries in mammals and in treatment of heart dysfunction subsequent to coronary occlusion. For illustrative purposes, the beneficial effect of administering PLP is demonstrated in the specific examples detailed below. The Examples describe both in vitro and in vivo experiments.

DESCRIPTION OF CLINICAL EXPERIMENTS

Example I - In Vitro - Ischemia Reperfusion in Isolated Rat Hearts and Measurement of Left Ventricular Developed Pressure Male Sprague-Dawley rats (200-250 g) were sacrificed by decapitation, and their hearts were rapidly removed and perfused according to the Langendorff procedure at a constant flow of 10 ml/min using the Kreb's-Heinsleit buffer (K-H buffer) oxygenated with 95% 02 and 5% C02, pH 7.4. After equilibration, a Langendorff Perfusion apparatus using K-H buffer was used to study the effect of PLP on ischemia reperfusion.

After an equilibration period of 15 min, total ischemia was induced by stopping the perfusion for 30 min while the hearts were kept at constant humidity and temperature of 37 C. In ischemic-reperfused hearts, perfusion with normal K-H
buffer was reinstated for 60 min after 30 min of global ischemia. The hearts were electrically stimulated (Phipps and Bird stimulator) at 300 beats/min via a square wave of 1.5 ms duration at twice the threshold voltage. The left ventricular developed pressure (LVDP), the rate of change in developed pressure (+dP/dt) and the rate of change in relaxation(-dP/dt) were measured by using a water filled latex balloon inserted into the left ventricle. The volume of the balloon as adjusted at the left ventricular end-diastolic pressure (LVEDP) of 10 mm Hg at the beginning of each experiment, and the balloon TM
was connected to pressure transducer (model 1050BP-BIOPAC SYSTEMS INC.).
Data was recorded on-line through analogue-digital interface (MP 100, BIOPAC
SYSTEMS INC.) and stored and processed with "Acknowledge 3.01 for Windows"
(BIOPAC SYSTEM INC.). In experiments where the effect of the pyridoxal-5'-phosphate (PLP) were studied, the hearts were perfused with PLP (15 M) + K-H
buffer for 10 min before inducing ischemia. This delivery of PLP (15 M) in the K-H
buffer was continued throughout the reperfusion period in these experiments.
The left ventricular developed pressure (LVDP) reflects the contractile activity of the heart.

Once the heart was reperfused after ischemia, it tends to become arrhythmic.
There is a time lapse before the heart stabilizes into a normal mode of rhythm.

The results of these experiments are shown below in Table 1. The control group comprised 13 animals, the PLP-treated group comprised 6 animals. All values in the Table are percentage of pre-ischemic values.

Global ischemia resulted in a decline of left ventricular developed pressure (LVDP). Reperfusion of the ischemic heart was found to induce a slow recovery of changes in LVDP. These parameters showed about 40% recovery over a 60 min reperfusion period.

On the other hand, about 80% recovery of depressions in LVDP was evident upon reperfusion of the hearts with PLP 10 min before inducing ischemia. Also the time to 50% recovery (time taken to reach half of the maximum contractile force recovery on reperfusion) was reduced in treated hearts.

Parameters Control Treated Time to regular rhythm (min) 18.3 5.0 5.3 2.1 LVDP - 30 min (% recovery) 30 8.6 78.2 9.2 LVDP - 60 min (% recovery) 44.2 9.3 84.7 6.3 Time to 50% recovery (Min) 39.3 8.1 16.0 4.6 Example 2 - Isolation of Membrane Preparation and Determination of Adenylyl Cyclase Activity At the end of each perfusion/reperfusion period, the heart was removed from the cannula and the crude membranes were prepared by the method used previously by Sethi et al., J. Cardiac Failure, 1(5) (1995) and Sethi et al., Am. J.
Physiol., iol., 272 (1997).
Briefly, the hearts were minced and then homogenized in 50 mM Tris-HC1, pH 7.5 (15 ml/g tissue) with a PT-20 polytron (Brinkman Instruments, Westbury, NY, USA), twice for 20s each at a setting of 5. The resulting homogenate was centrifuged at 1000 x g for 10 min and the pellet was discarded. The supernatant was centrifuged at 3048000 X g for 25 min. The resulting pellet was resuspended and centrifuged twice in the same buffer and at the same speed; the final pellet was resuspended in 50 mM Tris-HCI, pH
7.4 and used for various biochemical assays.

Adenylyl cyclase activity is increased during ischemia reperfusion leading to arrhythmias and damage to the myocardium due to increased cAMP levels and increased calcium entry. Treatment with PLP partially reverses this increased enzyme activity to control levels.

The adenylyl cyclase activity was determined by measuring the formation of [a-32P] cAMP [a-32P ] ATP as described by Sethi et al., supra. Unless otherwise indicated, the incubation assay medium contained 50 mM glycylglycine (pH 7.5), 0.5 mM Mg ATP, [[a-32P] ATP (1-1.5 x 106 cpm), 5 mM MgC12 (in excess of the ATP
concentration), 100 mM NaC1, 0.5 mM cAMP, 0.1 mM EGTA, 0.5 mM 3-isobutyl-l-methylxanthine, 10 U/ml adenosine deaminase, and an ATP regenerating system comprising of 2 mM creatine phosphate and 0.1 mg creatine kinase/ml in a final volume of 200 l. Incubations were initiated by the addition of membrane (30-70 ug) to the reaction mixture, which had equilibrated for 3 min at 37 C. The incubation time was 10 min at 37 C and the reaction was terminated by the addition of 0.6 ml 120 mM
zinc acetate containing 0.5 mM unlabelled cAMP. The [a-32P] cAMP formed during the reaction was determined upon coprecipitation of other nucleotides with NaCO3 by the addition of 0.5 ml 144 mM Na2CO3 and subsequent chromatography. The unlabelled cAMP served to monitor the recovery of [a-32P] cAMP by measuring absorbency at 259 nm. Under the assay conditions used, the adenylyl cyclase activity was linear with respect to protein concentration and time of incubation.

In a control Group C, the membrane preparation prepared as described in Example 2 was from hearts which, after a 20 minute stabilizing period, were perfused with normal K-H buffer or normal K-H buffer plus PLP for 90 minutes. In a group denoted IR (ischemia reperfusion), the membrane preparation was from hearts in which, after a 20 minute stabilizing period, ischemia was induced for 30 minutes followed by 60 minutes reperfusion with normal K-H buffer. In a group denoted PR, the preparation was from hearts in which, after a 20 minute stabilizing period, the hearts were perfused with 15 m PLP plus normal K-H buffer for 10 minutes, followed by ischemia induced for 30 minutes followed by 60 minutes reperfusion with normal K-H
buffer. Note that PLP was present all through the reperfusion period.

The results are shown in Table 2. They are from n=6 experiments.

Effect of various stimulants on adenylyl cyclase activity in rat heart crude membrane preparations from control (C), ischemia reperfusion (IR), and treated group (PR).

Adenyl Cyclase Activity pmol cAMP/mg protein/10 min Group Basal NaF (5 mM) Forskolin Gpp(NH)p (100 M) (30 gM) Control 296 32 2343 1 l 8 1423 102 1123 98 IR 529 21* 3490 176* 2192 111* 1865 81*
PR 391 18# 2960 132# 1804 129# 1492 101#
* P<0.05, significantly different from Control and PR group.
# P< 0. 05, signi ficantly different from Control and IR group.
Example 3 - In vivo - Coronary Artery Li ag tion Myocardial infarction was produced in male Sprague- Dawley rats (200-250 g) by occlusion of the left coronary artery as described by Sethi et al., supra.
Rats were anesthetized with 1-5% isoflurane in 100% 02 (2L flow rate). The skin was incised along the left sterna border and the 4th rib was cut proximal to the sternum and a retractor inserted. The pericardial sac was opened and the heart externalized.
The left anterior descending coronary artery was ligated approximately 2 mm from its origin on the aorta using a 6-0 silk suture. The heart was then repositioned in the chest and the incision closed via purse-string sutures. Sham operated rats underwent identical treatment except that the artery was not ligated. Mortality due to surgery was less than 1%. Unless indicated in the text, the experimental animals showing infarct size >30%
of the left ventricle were used in this study. All animals were allowed to recover, received food and water ad libitum, and were maintained for a period of 21 days for Electrocardiogram (ECG), hemodynamic and histological assessment.

Occlusion of the coronary artery in rats has been shown to produce myocardial cell damage which results in scar formation in the left ventricle and heart dysfunction.
While the complete healing of the scar occurs within 3 weeks of the coronary occlusion, mild, moderate and severe stages of congestive heart failure have been reported to occur at 4, 8 and 16 weeks after ligation. Accordingly, the contractile dysfunction seen at 3 weeks after the coronary occlusion in rats is due to acute ischemic changes.

The rats were housed in clear cages in a temperature and humidity controlled room, on a 12 hour light-dark cycle. Food and water were supplied ad libitum.
Rats at random were divided into five groups: sham operated, coronary artery ligated without treatment, sham operated with PLP treatment, coronary artery ligated with PLP
treatment (25 mg/kg body weight orally by gastric gauge) two days before surgery, and coronary artery ligated with PLP treatment (25 mg/kg body weight) one hour after surgery. These animals were used in all the studies below. For EKG studies, these animals were used as their controls before surgery, so that before surgery was done on these animals EKG traces were taken which were then used as controls for the same animals after surgery.

Example 4 - Hemodynamic Changes The animals prepared as described in Example 3 were anesthetized with an injection of cocktail of ketamine hydrochloride (60 mg/kg) and xylazine (10 mg/kg).
The right carotid artery was exposed, and cannulated with a microtip pressure transducer (model PR-249, Millar Instruments, Houston, TX). The catheter was advanced carefully through the lumen of the carotid artery until the tip of the transducer entered the left ventricle. The catheter was secured with a silk ligature around the artery. The hemodynamic parameters such as left ventricular systolic pressure (LVLSP), left ventricular end diastolic pressure (LVEDP), rate of contraction (+dP/dt), and rate of relaxation (-dP/dt) were recorded on a computer system (AcqKnowledge 3.1 Harvard, Montreal, Canada).

Myocardial infarction for 3 weeks produced a progressive increase in left ventricular end diastolic pressure (LVEDP) without any changes in either heart rate of left ventricular systolic pressure (LVSP). Furthermore, both rate of force of contraction (+dP/dt) and rate of force of relaxation (-dP/dt) were significantly depressed in the infarcted animals. The elevation in LVEDP and depression in both +dP/dt and -dP/dt were partially prevented upon treating the infarcted animals with PLP for 3 weeks.
The results are given below, in Tables 3 and 4.
Data are expressed as mean SE qf 10 animals. All measurements were made using a Miller microcatheter; the catheter was inserted into the left ventricle via cannulation of the right carotid artery. L VSP, left ventricular systolic pressure; L VEDP, left ventricular end- diastolic pressure; +dP/dt, rate of contraction; -dP/dt rate of relaxation. Animals were randomly divided into four groups: Sham, Sham + Drug treated, Drug treated starting at 2 days before ligation (PrD) for up to 21 days and coronary ligated group (Ml). Treatment group was given PLP (25 mg/kg body wt.) orally by gastric gauge once a day.

Hemodynamic parameters of rates with myocardial infarction with or without PLP
treatment for 21 days starting at 2 days before coronary artery ligation (PrD).

Parameters Sham Sham + MI PrD
Drug HR(beats/min) 376 18 398 22 405 22 475 16 LVSP (mm Hg) 126 7 122 6 128f6 123 6 LVEDP (mm Hg) 2.2 0.2 1.9 0.09 12.2+0.9* 5.7 0.9#
+dP/dt (mm Hg/s) 5899 302 5772+312 2654 111* 4272 223#
-dP/dt (mm Hg/s) 5469 284 5401 297 2348 99* 3998 179#
*(P< 0. 05) significantly different from the sham control and the PrD group.
#(P< 0. 05) significantly different from sham control group and MI group.

A later confirmation of hemodynamic parameters of rates with myocardial infarction with or without PLP treatment for 21 days starting at 1 hour after and 2 days before coronary artery ligation.

Parameters Sham Sham MI PP 1 PP2 + Drug (beats/min) LVSP 124+7 122 6 124 6 127 6 129 5 (mm Hg) LVEDP 2.2 0.2 1.9 0.09 12.2 0.9* 5.7 0.9*# 5.2 0.8*#
(mm Hg) +dP/dt 5899 302 5772 312 2654 111* 4272 223*# 4199 219*#
(mm Hg/s) -dP/dt 5469 284 5401 297 2348 99* 3998 179*# 3918 177*#
(mm Hg/s) *(P<0. 05) significantly different from the sham and sham + drug group.
#(P<0.05) significantly differentfrom MI group.

There were three groups of rats, 20 each: (MI) untreated coronary litigated, (PPl) orally PLP once daily starting at 1 hour after ligation, (PP2) orally PLP once daily starting at 2 days before ligation.
Example 5 - Electrocardio rg am (ECG) Recordings Six lead (I, II, III, aVr, aVf, aVI) ECG recordings were made from rats in all groups (sham operated, coronary artery ligated (MI), sham operated with drug treatment, coronary artery ligated with drug treatment 2 days before ligation, coronary artery ligation with drug treatment within 1 hour of ligation) prior to coronary artery ligation and at 1, 3, 7, 14 and 21 days after occlusion. Surface ECG's were recorded under isoflurane anesthesia using a model EC-60 Cardiac and Respiratory monitor (Silogic International Limited, U.K.). The ST segment abnormality was defined as depression or elevation of at least 1 mm from the base line that persisted for > 1 min. The magnitude of the ST segment shift was measured 60 ms after the J point in all of the six leads. The QT interval was measured by standard criteria and then corrected for heart rate using Bazett's formula (QTc = QT/square root of RR interval). The longest QT
interval of all lead was measured from onset of the Q-wave until termination of the T wave.
Onset of the R wave was used if Q waves were not present. The R-R interval immediately preceding the QT interval measurement was used to correct for heart rate.
Pathological Q-waves were defined as a negative deflection, at least 25 uV in amplitude, preceding the R-wave.

ST Segment Changes ST-segment depression reflecting subendocardial hypoperfusion is the most common ECG manifestation of ischemia, and ST segment deviation can be used as a noninvasive marker of the perfusion status of the heart. Electrodes positioned directly over the injured zone typically record ST segment elevation whereas those in opposite areas of the torso detect "reciprocal" ST segment depression. In the present study, ST
segment depression was recorded in lead I and ST segment elevation in leads II
and III
three leads at 1 to 21 days after coronary artery ligation in untreated rats.
Treatment with PLP attenuated the degree of ST segment elevation/depression following occlusion, and accelerated recovery of the ST segment. The results are shown below in Tables 5 and 6. In Table 5, the values for ST segment deviation recorded prior to the occlusion (control) for all the three leads for MI and PrD group were 0.01, 0.02, 0.01 and 0.015, 0.02 and 0.01 respectively. In Table 6, the values for ST segment deviation recorded prior to the occlusion (control) for all the three leads for MI and PrD group were 0.02, 0.02, 0.01 and 0.01, 0.009 and 0.015 respectively.

ST segment changes in rats with myocardial infarction (MI) with or without PLP
treatment for 21 days starting at 2 days before coronary artery ligation (PrD).
ST segment (mV) Group 7 Day 14 Day 21 Day Lead I
MI 0.17 0.02* 0.17 0.02* 0.15f0.01 *
PrD 0.08 0.01 0.05 0.01 0.03 0.01 Lead II
MI 0.15 0.01* 0.15 0.01 * 0.14 0.01*
PrD 0.07 0.01 0.04 0.01 0.03 0.01 Lead III
MI 0.18 0.02* 0.17 0.02* 0.14 0.01*
PrD 0.06 0.01 0.04 0.01 0.02 0.01 * P<0.05 compared to control and treated group.

ST segment changes in rats with myocardial infarction (MI with or without PLP
treatment for 7 days starting at 1 hour after coronary artery ligation (PrD).

ST segment (mV) Grou 1 Day 3 Day 7 Day Lead I
MI 0.19 0.02* 0.19 0.02* 0.16 0.01*
PrD 0.13 0.01 0.09 0.01 0.07 0.01 Lead II
MI 0.20 0.01 * 0.19 0.01 * 0.17 0.01 *
PrD 0.14 0.01 0.10 0.01 0.07 0.01 Lead III
MI 0.20 0.02* 0.18 0.01* 0.15 0.01 *
PrD 0.13 0.01 0.08 0.01 0.04 0.01 * P< 0. 05 compared to control and treated group.

QT Interval and Mortality FollowingMyocardial Infarction The QT interval on the surface electrocardiogram is an indirect measure of the ventricular action potential duration and its prolongation is often associated with the occurrence of malignant ventricular arrhythmias in patients. A long QT
interval on the ECG is associated with a higher risk of sudden cardiac death following myocardial infarction. The data indicates that QT interval prolongation occurred by 1 day and then gradually declined from 3-21 days which coincided with the period of highest mortality following ligation in untreated rats. Treatment with PLP attenuated the QT
prolongation and also accelerated the time course of recovery of the QT
interval following coronary occlusion.

The results are given below in Tables 7, 8 and 9.

Myocardial infarction was induced by coronary ligation. All the animals remaining after subsequent weeks were used for ECG estimations. Values are mean SE. Treated animals were given PLP (25 mg/kg) orally once or twice a day.
Control values were taken before the induction of myocardial infarction.

Time dependent changes of QTc interval (msec) in myocardial infarction with or without PLP treatment for up to 21 days starting at 2 days before coronary artery ligation (PrD).

Group Control 7 Day 14 Day 21 Day MI 302 17 563 32* 522 26* 506 29*
PrD 313 21 456 22*# 437 23*# 410 21*#
* P< 0. 05 compared to control.

# P<0.05 compared with MI group.

There were two groups of rats, 20 each: (MI) untreated coronary litigated, (PrD) PLP orally once daily.

Later confirmation and expansion of time dependent changes of QTc interval (msec) in myocardial infarction with or without PLP treatment for up to 21 days starting at 2 days before coronary artery ligation.

Group Control 1 Day 3 Day 7 Day 21 Day MI 302 17 601 17* 571 18* 522 26* 506 29*
PPI 313 23 530 25*# 486 15*# 457 23*# 410 21#
PP2 316 24 541 33*# 495 31*# 452f19*4 401 17*
* P<0.05 compared to control.
# P<0.05 compared with MI group.

There were three groups of rats, 20 each: (MI) untreated coronary litigated, (PPl) orally PLP once daily, (PP2) orally PLP twice daily. n=20, values mean SE.
Control values taken before induction of myocardial infarction.

Time dependent changes of QT,, interval (msec) in myocardial infarction with or without PLP treatment for up to 21 days starting at 1 hour after coronary artery ligation.
Group Control 1 Day 3 Day 7 Day 21 Day MI 322 17 594 22* 562 18* 540 20* 503 22*
PPI 310 21 516 21*# 505 13*# 430 11*# 404 18*#
PP2 311 14 535 23*# 484 21-# 421 26*# 397 19*#
* P<0.05 compared to control.
# P< 0. 05 compared with MI group.

There were three groups of rats, 20 each: (MI) untreated coronary litigated, (PPI) orally PLP once daily, (PP2) orally PLP twice daily. n=20, values are mean SE.
Control values were taken before induction of myocardial infarction.

Accordingly the mortality rate was also significantly less in the PLP treated group.

Mortality Rates Most early deaths after myocardial infarction occur within the first few hours and these are caused primarily by lethal ventricular arrhythmias. In the present study, mortality was highest in the first 48 hours after coronary ligation in both untreated and treated rats, however, mortality was significantly less in treated animals.
This decreased mortality was accompanied by several improved ECG findings suggesting an antiarrhythmic action of PLP (decreased incidences of pathological Q-waves and PVCS).

Rats intended for operating on, were randomly divided into four groups, each 20:
Sham, Sham + Drug treated, Drug treated starting at 2 days before ligation (MI
+ Drug) for up to 21 days and Coronary ligated (MI). Since the sham and sham + drug group had no differences in regards to mortality and other hemodynamic changes, they were considered as one group. The results are shown below in Tables 10, 11, 12 and 13.

Mortality in rats with myocardial infarction with or without PLP treatment for 21 days starting at 2 days before coronary artery ligation (PrD).

No. of animals (%) Mortality [MI PrD
On the lst day 30 15 On the 2nd day 10 5 On the 3rd day 5 0 Within 21 days (%) ## 45 20*

* Significantly (P<0.05) different from the MI group. Sham group had no mortality.

## At the 21 st day, 3 animals from the MI group appeared very sick and may not have survived another week.

Later confirmation and expansion of mortality in rats with myocardial infarction with or without PLP treatment for 21 days starting at 2 days before coronary artery ligation.

No. of animals (%) Mortality MI PP 1 PP2 On the lst day 30 20 20 On the 2nd day 10 5 5 On the 3rd day 5 0 5 Within 21 days (%) 45 25* 30*
* Significantly (P<0.05) different from the MI group.

(MI) untreated coronary litigated, (PPl) orally PLP once daily, (PP2) orally PLP
twice daily.

In a second, similar test, rats intended for operating on, were randomly divided into four groups, 20 each: Sham, Sham + Drug treated, drug treated starting at 1 hour after ligation (PrD) for up to 7 days and coronary ligated group (MI). Since the sham and sham + drug group had no differences in regards to mortality and other hemodynamic changes, they were considered as one group.
The results are shown below in Table 12.

Mortality in rats with myocardial infarction with or without PLP treatment for 7 days starting at 1 hour after coronary artery ligation (PrD).

No. of animals (%) Mortality [MI PrD
On the lst day 25 15 On the 2nd day 15 5 On the 3rd day 5 0 Within 7 days (%) 45 20*

* Significantly (P< 0. 05) different from the MI group. Sham group had no mortality.

Later confirmation and expansion of mortality in rats with myocardial infarction with or without PLP treatment for 21 days starting at 1 hour after coronary artery ligation.

No. of animals (%) Mortality MI PP 1 PP2 On the lst day 30 20 16 On the 2nd day 10 8 8 On the 3rd day 5 0 0 Within 21 days (%) 45 28* 24*

* Significantly (P< 0. OS) different from the MI group.
There were three groups of rats: (MI), 20 rats, untreated coronary litigated, (PPl), 25 rats, orally PLP once daily, (PP2), 25 rats, orally PLP twice daily.

Antiarrythmic Action of PLP Revealed by ECG's The ECGs of the animals in the previously reported tests for mortality rate showed several findings indicating an antiarrythmic action of PLP. One of these is a decreased incidence of pathological Q-waves.

These results are shown in Tables 14 and 15 below.

General Characteristics and pathological "Q" wave appearance of rats with myocardial infarction with or without PLP treatment for up to 21 days, starting at 1 hour after coronary artery ligation.

Parameters Sham Sham MI PP 1 PP2 + Drug Body wt.(g) 321 3 312 4 332 5 342 7 344 10 Q wave appearance -- -- 58 27* 38*
within 21 days (%) (Pathological) Infarct size -- -- 43 21 * 23*
(% of LV) * Significantly (P<0.05) different from the MI group.

There were three groups of rats, 20 each: (MI) untreated coronary litigated, (PP1) orally PLP once daily, (PP2) orally PLP twice daily. n=20, values are mean SE.
Sham group was given saline.

General Characteristics and pathological "Q" wave appearance of rats with myocardial infarction with or without PLP treatment for up to 21 days, 2 days after coronary artery ligation.

Parameters Sham Sham + MI PP 1 PP2 Drug Body wt. (g) 330 8 322 5 331 7 332 9 334 10 Q wave appearance -- -- 62 37* 39*
within 21 days (%) (Pathological) Infarct size -- -- 43 27* 32*
(% of LV) * Significantly (P<0.05) different from the MI group.

There were three groups of rats, 20 each: (MI) untreated coronary litigated, (PPl) injected PLP once daily, (PP2) injected PLP twice daily. n=20, values are mean SE.
Sham group was given saline.

Another such finding is a decreased incidence of preventricular contraction (PVC) following coronary artery ligation. These results are shown in Tables 16 and 17 below.

Effect of treatment with PLP (starting at 2 days before ligation continued for 21 days) on the incidence of preventricular contraction (PVC) following coronary artery ligation.
PVC Incidence (%) Group 7 Day 14 Day 21 Day PrD 2* 3* 3*
*Significantly (P< 0. 05)different from the MI group.

Effect of treatment with PLP (starting at 1 hour after ligation continued for 7 days) on the incidence of preventricular contraction (PVC) following coronary artery ligation.

PVC Incidence (%) Group 1 Day 3 Day 7 Day PrD 1* 1* 3*

* Significantly (P<0.05) differentftom the MI group.

As those skilled in the art would realize these preferred described details and compounds and methods can be subjected to substantial variation, modification, change, alteration, and substitution without affecting or modifying the function of the described embodiments.

Although embodiments of the invention have been described above, it is not limited thereto, and it will be apparent to persons skilled in the art that numerous modifications and variations form part of the present invention insofar as they do not depart from the spirit, nature and scope of the claimed and described invention.

It must be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a composition containing "a compound" includes a mixture of two or more compounds.

Claims (17)

1. The use of a compound wherein the compound is one or more of the following alternatives: pyridoxal-5'-phosphate, pyridoxine, pyridoxal, or pyridoxamine, for the treatment of ischemia reperfusion and ischemia-related cellular dysfunction in mammals.

2. The use of claim 1, wherein said compound is in an amount of about 1-50 mg/kg of a patient's body weight.

3. The use of claim 1, wherein said compound is in an amount of about 5-25 mg/kg of a patient's body weight.

4. The use of claim 1, wherein said compound is for administration enterally or parenterally.

5. The use of claim 1, wherein said compound is pyridoxal-5'-phosphate.

6. The use of a compound wherein the compound is one or more of the following alternatives: pyridoxal-5'-phosphate, pyridoxine, pyridoxal, or pyridoxamine, for the treatment of ischemia reperfusion injury.

7. The use of a compound wherein the compound is one or more of the following alternatives: pyridoxal-5'-phosphate, pyridoxine, pyridoxal, or pyridoxamine, for the treatment of ischemia-related cellular dysfunction.

8. A pharmaceutical composition for the treatment of ischemia-related conditions comprising: a pharmaceutically acceptable carrier and a therapeutic amount of a compound wherein the compound is one or more of the following alternatives: pyridoxal-5'-phosphate, pyridoxine, pyridoxal, or pyridoxamine.

9. The pharmaceutical composition of claim 8, wherein said compound is pyridoxal-5'-phosphate.

10. The pharmaceutical composition of claim 8, wherein said pharmaceutical composition is in a form suitable for enteral or parenteral administration.

11. The use of a compound wherein the compound is one or more of the following alternatives: pyridoxal-5'-phosphate, pyridoxine, pyridoxal, or pyridoxamine, for preparing a pharmaceutical composition for treating ischemia reperfusion and ischemia-related cellular dysfunction in mammals.

12. The use of claim 11, wherein said compound is in an amount of about 1-50 mg/kg of a patient's body weight.

13. The use of claim 11, wherein said compound is in an amount of about 5-25 mg/kg of a patient's body weight.

14. The use of claim 11, wherein said compound is for administration enterally or parenterally.

15. The use of claim 11, wherein said compound is pyridoxal-5'-phosphate.

16. The use of a compound wherein the compound is one or more of the following alternatives: pyridoxal-5'-phosphate, pyridoxine, pyridoxal, or pyridoxamine, for preparing a pharmaceutical composition for treating ischemia reperfusion injury.

17. The use of a compound wherein the compound is one or more of the following alternatives: pyridoxal-5'-phosphate, pyridoxine, pyridoxal, or pyridoxamine, for preparing a pharmaceutical composition for treating ischemia-related cellular dysfunction.