INTRODUCTION:

Cardiovascular disease (CVD) is a general term that describes a disease of the heart or blood vessels: Blood flow to the heart, brain or body can be reduced as the result of a blood clot (thrombosis), or by a build-up of fatty deposits inside an artery that cause the artery to harden and narrow (atherosclerosis).^[1]Cardiovascular diseases remain the principal cause of death in both, developed and developing countries accounting for roughly 20% of all deaths worldwide per year.^[2]Cardiovascular disease includes heart disease (i.e., myocardial infarction and angina), stroke, hypertension, congestive heart failure (CHF), and other Circulatory system diseases.

It is the number one cause of death in America, responsible for more than 40% of annual deaths. An average of 1 death due to CVD occurs every 33 seconds in the United States.It remains the major cause of premature death in Europe, even though CVD mortality has fallen considerably over recent decades in many European countries. It is estimated that >80% of all CVD mortality now occurs in developing countries^[.^3]CVD has emerged as the leading cause of death in India. Overall, CVDs accounted for one-fourth of all deaths in India in 2008. CVDs are expected to be the fastest growing chronic illnesses between 2005 and 2015, growing at 9.2 % annually.^[4] According to world health organization it is predicted that CVD will be the most important cause of mortality in India by 2020.^[5] CVD is strongly connected to lifestyle, especially the use of tobacco, unhealthy diet habits, physical inactivity, and psychosocial stress.^[6]

Acute myocardial infarction (MI) remains a leading cause of morbidity and mortality worldwide. Myocardial infarction occurs when myocardial ischemia, a diminished blood supply to the heart, exceeds a critical threshold and overwhelms myocardial cellular repair mechanisms designed to maintain normal operating function and homeostasis. It is the acute condition at necrosis of the myocardium that occurs as a result of imbalance between coronary blood supply and myocardial demand.^[7] An interruption in the supply of myocardial oxygen and nutrients occurs, when a thrombus is superimposed on an ulcerated or unstable atherosclerotic plaque and results in coronary occlusion.^[8]The evidence of MI can be identified by elevations of different proteins released into the blood by the damaged myocytes.⁹Most myocardial infarctions are caused by a disruption in the vascular endothelium associated with an unstable atherosclerotic plaque that stimulates the formation of an intracoronary thrombus, which results in coronary artery blood flow occlusion. Disruption of the endothelial surface causes and it lead to the formation of thrombus via platelet-mediated activation of the coagulation cascade. If a thrombus is large enough to occlude coronary blood flow, an MI can result.^[10,11]Doxorubicin induced cardiotoxicity is a standard model to study the cardiac dysfunction. The possible mechanisms proposed for cardiotoxic effects of Doxorubicin include free radical induced myocardial injury, lipid peroxidation, mitochondrial damage, decreased activity of Na⁺-K⁺ adenosine triphosphate, vasoactive amine release and cellular toxicity. ^[12]

MATERIALS AND METHODS:

EXPERIMENTAL ANIMALS:

Albino Wistar rats, weighing 200 – 250 g were obtained from central animal house of Swamy Vivekanandha College of Pharmacy, Elayampalayam, Tiruchengode. The animals were acclimatized for 2 weeks in laboratory conditions before experiment. The animals were housed in polypropylene cages maintained under standard environmental conditions (12h light/12h dark cycle: temperature25± 3°c, relative humidity 35-60%) and rats were provided with standard pellet diet and water ad libitium freely throughout the study Study protocol was approved by institutional animal ethics committee (IAEC), Swamy Vivekanadha College of Pharmacy (Proposal. No.SVCP/IAEC/M.Pharm/1/01/2016 and the study was conducted in accordance with guidelines set by CPCSEA (Committee for the purpose of control and supervision of experiment on animals).

DRUGS AND CHEMICALS:

Pure samples of telmisartan, metformin, were obtained as gift samples from saimirra inno pharmaceuticals Pvt. Limited, Ambattur, Chennai. Doxorubicin was obtained from Thangam hospital, namakkal. 0.1N Sodium hydroxide (NaOH), Chloroform, Diethyl ether was used of analytical grade.

EXPERIMENTAL PROTOCOL:

The rats were divided into eight groups consisting of three animals of either sex per group (n = 6).

Group I:

Received saline daily for 15 days and served as the control.

Group II:

Received doxorubicin (15 mg/kg, ip) on 14^th, 15^thday.

Group III:

Received telmisartan (5mg/kg, po), daily for 15days, and doxorubicin on 14^th, 15thday,one hour after drug administration, doxorubicin (15mg/kg) was administered intraperitoneally

Group IV:

Received received telmisartan (10mg/kg, po), daily for 15days, and on 14^th, 15thday, one hour after drug administration, doxorubicin (15mg/kg) was administered intraperitoneally.

Group V:

Received metformin (150mg/kg, po), daily for 15days, and on 14^th, 15thday, one hour after drug administration, doxorubicin (15mg/kg) was administered intraperitoneally.

Group VI:

Received metformin (300mg/kg, po), daily for 15days, and on 14^th, 15thday, one hour after drug administration, doxorubicin (15mg/kg) was administered intraperitoneally

Group VII:

Received telmisartan (5mg/kg) and metformin (150mg/kg,) po, daily for 15days, and on 14^th, 15thday, one hour after drug administration, doxorubicin (15mg/kg) was administered intraperitoneally.

Group VIII:

Received telmisartan (10mg/kg, metformin (300mg/kg) po, daily for 15days, and on 14^th, 15thday, one hour after drug administration, doxorubicin (15mg/kg) was administered intraperitoneally.

On the 15th day, all the rats were anaesthetized and blood was collected from the retro-orbital sinus, the blood was centrifuged and the serum was used for the biochemical assay.

RESULTS:

EFFECT OF DRUGS IN MARKER ENZYME OF RATS BLOOD SERUM:

Cardioprotective activity was performed by observing the parameter such as troponin, CK-MB, LDH. The result revealed that increase in level of troponin, CK-MB & LDH shows that there is a chance of occurring myocardial infarction. The following table gives the result of all respective groups.

Fig. 1: Effect of drugs on Troponin T

Fig. 2: Effect of drugs on CK-MB

All the values are expressed in mean, ±SEM by using student t-test, the level of CK-MB compared with normal and doxorubicin group where the significant ranges as follow,^*P<0.1 V_Scontrol group, ^# P<0.1,^## P<0.05, ^# P<0.1,^### P<0.02, ^# P<0.1, ^#### P<0.001 Vs doxorubicin group

Fig.no.3: Effect of drugs on LDH

All the values are expressed in mean, ±SEM by using student t-test, the level of LDH compared with normal and doxorubicin control where the significant ranges as follow,^* P<0.1, **P<0.05,^* P<0.1,^*** P<0.02,* P<0.1,****P<0.001 Vs control group

^#P<0.1 Vs doxorubicin group.

TABLE: 1

GROUP	TROPONIN	CK-MB	LDH
GROUP 1	Negative	17± 1.012	257.5±5.255
GROUP 2	Positive	32±0.589	430.8 ±3.24
GROUP 3	Negative	20.5±0.779^{* #}	298.15 ±3.938^{* #}
GROUP 4	Negative	19.28±0.569^{* ##}	279.5 ±4.877**^#
GROUP 5	Negative	22.83±0.613^{* #}	304.33 ±3.842*^#
GROUP 6	Negative	20.85±0.680^{* ###}	294.33±3.424***^#
GROUP 7	Negative	20.66±0.569^{* #}	289.4 ±4.360^{* #}
GROUP 8	Negative	17.5±0.731^{* ####}	270.8 ±2.82^{**** #}

Myocardial infarction was induced by administration of doxorubicin by inducing free radical myocardial injury, lipid peroxidation, and mitochondrial damage, decreasing the activity of Na⁺K⁺ ATP ase vasoactive amine release, impairment in myocardial adrenergic signaling / regulation, increase in serum total cholesterol, triglyceride and low density lipoprotein. In this study, the level of troponin, CK-MB, LDH in serum compared with normal and doxorubicin control and the levels are expressed in mean, ±SEM by using student t-test, where the significant ranges at P<0.1,^*P<0.05,^**,P<0.02^***, P<0.001^****for control groups. The significant ranges at P<0.1^#, P<0.05^##, P< 0.02^### P<0.001^####for doxorubicin groups. For troponin, only doxorubicin control is positive and remaining drug treated and the normal control is positive. Then the level of CK-MB and LDH of drug treated was compared with normal and doxorubicin control. For CK-MB, it was found where telmisartan (5mg/kg), telmisartan (10mg/kg) metformin (150mg/kg), metformin (300mg/kg), telmisartan (5mg/kg)+ metformin (150mg/kg), telmisartan (10mg/kg)+ metformin (300mg/kg) is significant(P<0.1) compare to normal. Telmisartan (5mg/kg) is significant (P<0.1) compare to doxorubicin control. Telmisartan(10mg/kg) is moderately significant (P<0.05) compare to doxorubicin control.Metformin (150mg/kg) is significant (P<0.1) compare to doxorubicin control.Metformin (300mg/kg) is moderately significant (P<0.02) compare to doxorubicin. Telmisartan (5mg/kg) + metformin (150mg/kg) is significant (P<0.1) compare to doxorubicin control. Telmisartan (10mg/kg) + metformin (300mg/kg) is highly significant (P<0.001) compare to doxorubicin control.

For LDH, it was found, where telmisartan (5mg/kg) is highly significant (P<0.001) compare to normal control. Telmisartan (10mg/kg) is moderately significant (P<0.05) compare to normal control, metformin (150mg/kg) is significant (P<0.1) to normal control, metformin (300mg/kg) is moderately significant (P<0.02) to normal control, telmisartan (5mg/kg) +metformin (150mg/kg) is significant (P<0.1) compare to normal, telmisartan(10mg/kg) + metformin (300mg/kg) is highly significant (P<0.001) compare to normal control. Telmisartan (5mg/kg),telmisartan (10mg/kg), metformin (150mg/kg), metformin (300mg/kg), telmisartan (5mg/kg) + metformin (150mg/kg), telmisartan (10mg/kg) + metformin (300mg/kg) is significant (P<0.1) compare to doxorubicin control.

From the present study, it is clear that metformin and telmisartan in combination and in alone has cardioprotective activity. It also shows its effect at both low and high dose against doxorubicin induced myocardial infarction. In doxorubicin control group, the cardiac biomarkers were increased in myocardium. But for drug treated groups, the level of cardiac biomarkers decreased and shows the cardioprotective activity.

CONCLUSION:

Telmisartan is well established drug for hypertension and metformin is for diabetics, In addition to their effects, both the drugs show their beneficial activity in cardioprotection. So, from the study telmisartan, metformin alone has reduced the severity of doxorubicin induced myocardial infarction, but in combination it shows better cardioprotective activity, when compare to telmisartan, metformin alone by using specific cardiac biomarkers like Troponin-T, CK-MB, LDH.

The possible mechanism of telmisartan which produces cardioprotection may be due to PPAR-gamma agonist properties and metformin which produces cardioprotection may be due to AMPK activity. Therefore, telmisartan and metformin alone and in combination produces cardioprotective activity. Therefore it may be prescribed with other cardioprotective drugs for better treatment of myocardial infarction in patients with hypertension and diabetics; eventhough further molecular level is required in order to acknowledge the results.

REFERENCE:

1. Rajadurai M, Stanely mainzen prince P et al., Preventive effect of naringin on isoproterenol induced cardio toxicity in Wistar rats. Toxicology 2007; 232:21-25.

2. American Heart Association. 2002 heart and stroke statistical update. Available at: http://www.american heart.org. Accessed December 17, 2002.

3. SIGN (Scottish Intercollegiate Guidelines Network). Risk Estimation and the Prevention of Cardiovascular Disease. A National Clinical Guideline 2007.

4. Nutrition transition in India, 1947-2007.ministry of women and child welfare.

5. Upaganlawar A, Patel V, Balaraman R et al., Tomato lycopene attenuates myocardial infarction induced by isoproterenol electrocardiographic, biochemical and anti-apopitotic study. APJTB 2012; 56-78.

6. World Health Organization. Joint WHO/FAO Expert Consultation on Diet, Nutrition and the Prevention of Chronic Diseases 2002. Report No. 916

7. Boudina S, Laclau MN, Tariosse L, Daret D, Gouverneur G, Bonoron-Adele S, Saks V A & Santos P D: Alteration of mitochondrial function in a model of chronic ischemia in vivo in rat heart, Am J Physiol Heart Circ Physiol., 2002; H821.

8. Cotran RS, Kumar V, Robbins SL (eds): Robbins Pathologic Basis of Disease. 5th ed. Philadelphia: WB Saunders, 1994.

9. Brien PJ, Smith DEC, Knechtel TJ, Marchak M.A et al., Cardiac troponin I is a sensitive, specific biomarker of cardiac injury in laboratory animals. Lab Anim, 2006; 40: 153-171.

10. Dohl T et al., April 2010 “change of concept & pathophysiology in acute coronary syndrome”. Nippon rinsho (in japanese) 68(4):592-6

11. Pathogenic basis of disease by robbins and cortan, 7 ^thedition. The Heart, chapter 12, Pg No :577

12. Loren EW et al., Doxorubicin induces cardiomyocyte dysfunction via p38 MAP kinase dependent oxidative stress mechanism. Cancer Detect Prev. 2005; 29:294–9.

Received on 17.05.2018 Modified on 16.06.2018

Research J. Pharm. and Tech 2018; 11(12): 5293-5296.

DOI: 10.5958/0974-360X.2018.00964.2