Isoproterenol-induced Myocardial Necrosis In Rats Research Articles

Cardioprotective effect of vincristine on isoproterenol-induced myocardial necrosis in rats

This study investigated the protective effect of vincristine (VCR) on isoproterenol (ISO)-induced cardiac necrosis (CN) in rats. Animals (n=7 in each group) were pretreated with vincristine (25µg/kg) intraperitoneal (i.p.) daily in 5-day cycles with 2 days pause between cycles using a 5-day-on, 2-day-off schedule for two weeks and then intoxicated with isoproterenol (100mg/kg, s.c., for 2 consecutive days). ISO-induced myocardial damage was indicated by changes in electrocardiographic (ECG) patterns, increased activities of marker enzymes such as creatine kinase-MB, serum glutamate pyruvate transaminase and lactate dehydrogenase and the levels of troponin-T in the serum. The levels of lipid peroxide products, (thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides (HP)) were increased with a parallel decrease in the activities of antioxidants (superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione) in ISO-induced rats. Furthermore, ISO-induced rats showed increase in the activities of membrane bound enzymes such as Ca2+-ATPase and Mg2+-ATPase with a decreased activity of Na+/K+-ATPase. Triphenyl tetrazolium chloride (TTC) staining of the heart section showed increased area of necrosis in ISO-induced rats. Pretreatment with VCR (25µg/kg) eliminated all ISO-induced biochemical and histopathological changes, and decreased the myocardial necrosis to a greater extent. Transmission electron microscopic findings on the structure of the heart mitochondria confirmed the protective effects of VCR. Present study provides first scientific report on protective effect of vincristine against ISO-induced cardiac damage in rats.

Dietary palm olein oil augments cardiac antioxidant enzymes and protects against isoproterenol-induced myocardial necrosis in rats

Wistar rats, 150-200 g, of either sex, were fed daily with commercial rat diet supplemented with palm olein oil in two doses (5% v/w (n = 16) and 10% v/w (n = 16) of diet) for 30 days. Control rats (n = 16) were fed with normal diet. On the 29(th) and 30(th) days, 8 rats from each group were administred isoproterenol (85 mg/kg, s.c., 24-h interval). On the 31(st) day, all rats were sacrificed and myocardial tissues were studied for thiobarbituric acid reactive substances (TBARS), antioxidant enzymes and light microscopic changes, along with the ferric-reducing ability of plasma (FRAP). A significant rise in myocardial superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) activity and FRAP level were observed in rats fed with palm olein oil. Isoproterenol caused an increase in myocardial oxidative stress in control rats, as evidenced by an increase in myocardial TBARS level, reduction in FRAP and myocardial SOD, catalase and GPx activity, along with focal necrosis of cardiac muscle fibres on light microscopy. The rise in myocardial TBARS and depletion of SOD and catalase activity following isoproterenol administration were prevented in palm-olein-oil-supplemented diet-fed rats at both doses. Isoproterenol-induced myocardial light-microscopic changes were also prevented in the treated groups. The results suggest that dietary palm olein oil caused augmentation of myocardial antioxidant enzymes and protected against isoproterenol-induced myocardial necrosis and associated oxidative stress.

Mitigation of mitochondrial dysfunction and regulation of eNOS expression during experimental myocardial necrosis by alpha-mangostin, a xanthonic derivative from Garcinia mangostana

Oxidative stress can play a key role in myocardial necrosis. The present study was designed to investigate the effect of alpha-mangostin (an antioxidant phytonutrient) on mitochondrial dysfunction and endothelial nitric oxide synthase (eNOS) expression during isoproterenol-induced myocardial necrosis in rats. Induction of rats with isoproterenol (ISO) (150 mg/kg body weight, intraperitoneally) for 2 days resulted in a significant decrease in the activities of respiratory chain enzymes (NADH dehydrogenase and cytochrome c oxidase), tricarboxylic acid cycle enzymes (isocitrate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, and alpha-ketoglutarate dehydrogenase), mitochondrial antioxidants (GPx, GST, SOD, CAT, and GSH), mitochondrial cytochromes (b, c, c1, and aa3), and adenosine triphosphate level. A marked elevation in mitochondrial lipid peroxidation was also observed in ISO-intoxicated rats. Pretreatment with alpha-mangostin (200 mg/kg body weight) orally for 8 days significantly attenuated these functional abnormalities and restored normal mitochondrial function, when compared to the ISO-intoxicated group of rats. Cardiac eNOS expression was assessed by Western blot. Cardiac eNOS expression and NO level were significantly suppressed in ISO-intoxicated rats. Pretreatment with alpha-mangostin extenuated ISO-induced diminution of eNOS expression and NO level. Transmission electron microscopic observations also correlated with these biochemical parameters. Hence, these findings conclude the ameliorative potential of alpha-mangostin against ISO-induced biochemical and morphological changes in mitochondria, which might be mediated through the NO pathway and by its ability at quenching free radicals.

Cardioprotective effect of ‘Khamira Abresham Hakim Arshad Wala’ a Unani formulation in isoproterenol-induced myocardial necrosis in rats

The present study was designed to investigate whether Khamira Abresham Hakim Arshad Wala (KAHAW), a preparation of Unani System of Medicine, is able to attenuate the isoproterenol (ISO)-induced myocardial necrosis on the basis of its effects on hemodynamic, antioxidant, histopathological and ultrastructural parameters. Male Wistar albino rats were administered KAHAW (200, 400 and 800 mg/kg/day, orally) or vehicle for 14 days with concurrent ISO administration (85 mg/kg, subcutaneously, 2 doses at 24 h interval) on 13th and 14th day. On the 15th day, vehicle+ISO-treated rats exhibit cardiac dysfunctions as indicated by decrease in systolic, diastolic, and mean arterial pressures, reduction in both maximum positive and maximum negative rates of developed left ventricular pressure (±LVdp/dt) and an increase in left ventricular end-diastolic pressure (LVEDP). Biochemical analysis of their heart homogenate presented reduced levels of enzymes viz., superoxide dismutase (SOD), catalase (CAT), lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB) isoenzyme. A marked reduction in reduced glutathione (GSH) levels along with increase in levels of thiobarbituric acid reactive substances (TBARS) was also observed in rat myocardium. Myocardial necrosis, edema and inflammation were evident from the light microscopic and ultrastructural changes. KAHAW at dose of 800 mg/kg/day significantly reversed majority of hemodynamic and antioxidant derangements. The protective role of KAHAW on ISO-induced myocardial necrosis was further confirmed by histopathological and ultrastructural examination. There was no significant change in heart rate in all experimental groups. KAHAW per se groups showed no significant change when compared with vehicle control group. The study results thus demonstrated the cardioprotective potential of KAHAW against ISO-induced myocardial necrosis and associated oxidative stress.

Cardioprotective activity of Ginkgo biloba Phytosomes in isoproterenol-induced myocardial necrosis in rats: A biochemical and histoarchitectural evaluation

The protective effects of Ginkgo biloba Phytosomes (GBP) in isoproterenol (ISO)-induced cardiotoxicity and the antioxidant activity involved in this protection were investigated in rats. Myocardial infarction was produced in rats with 65, 85, 120 and 200 mg/kg of ISO administered subcutaneously (sc) twice at an interval of 24 h. An ISO dose of 85 mg/kg was selected for the present study as this dose offered significant alteration in biochemical parameters and moderate necrosis in heart. Effect of GBP oral treatment for 21 days at two doses (100 mg and 200 mg/kg body weight) was evaluated against ISO (85 mg/kg, sc)-induced cardiac necrosis. Levels of marker enzymes (AST, LDH and CPK) were assessed in serum and heart, antioxidant parameters viz., reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) and malondialdehde (MDA) were assayed in heart homogenate. Significant myocardial necrosis, depletion of endogenous antioxidants and increase in serum levels of marker enzymes were observed in ISO-treated animals when compared with the normal animals. GBP elicited a significant cardioprotective activity by lowering the levels of serum marker enzymes and lipid peroxidation and elevated the levels of GSH, SOD, CAT, GPx and GR. The present findings have demonstrated that the cardioprotective effects of GBP in ISO-induced oxidative damage may be due to an augmentation of the endogenous antioxidants and inhibition of lipid peroxidation of membrane.

Cardioprotective response to chronic administration of vitamin E in isoproterenol induced myocardial necrosis: Hemodynamic, biochemical and ultrastructural studies

The present study evaluated the cardioprotective potential of vitamin-E by studying its effect on hemodynamic parameters, lipid peroxidation, myocyte injury marker and ultrastructural changes in model of isoproterenol-induced myocardial necrosis in rats. Wistar albino male rats (150-200 g) were randomly divided into saline, ISP control, and vit E groups. Vitamin E group was administered vitamin E at a dose of 100mg/kg/day while saline and ISP control groups received saline orally for one month. On 29(th) and 30(th) day, ISP (85 mg/kg, sc) was administered at an interval of 24 h to vit E and ISP control rats. On 31(st) day, rats of all groups were anesthetized and hemodynamic parameters were recorded. At the end of experimentation, animals were sacrificed; hearts were excised and processed for biochemical and ultrastructural studies. ISP administration produced marked cardiac necrosis as evidenced by significant decrease in my ocardial creatine kinase-MB as well as increase in malonaldialdehyde levels. ISP-induced myocardial necrosis resulted in myocardial dysfunction as evidenced by significant depression in heart rate and mean arterial pressure in the ISP control group as compared to saline control. Salient ultrastructural changes including extensive loss of myofibrils, muscle necrosis, loss of mitochondria, and formation of several intracytoplasmic vacuoles and lipid droplets further confirmed the ISP-induced myocardial damage. However, subsequent to ISP challenge, vit E treatment significantly preserved the myocardium by restoring myocardial CK-MB activity, inhibiting the ISP-induced lipid peroxidation and ultrastructural changes. Additionally, pre-and co-treatment of vit E prevented the deleterious ultrastructural changes caused by ISP. These beneficial effects of chronic vit E treatment also translated into significant restoration of the altered hemodynamic parameters. The present study clearly demonstrated the cardioprotective potential of vit E at dose of 100 mg/kg in ISP-induced model of myocardial necrosis in rats. The significant restoration of altered hemodynamic parameters, myocardial CK-MB activity, prevention of ISP-induced rise in lipid peroxidation and ultrastructural changes may confirm its cardioprotective effect.

Effect of D-003 on isoproterenol-induced myocardial necrosis in rats.

D-003 is a mixture of high-molecular-weight aliphatic primary acids purified from sugar cane wax with antiplatelet and cholesterol-lowering effects. Cardiac lesions induced by isoproterenol (ISO) are characterized by myocardial necrosis and exudative infiltration. The objective of this study was to determine whether D-003 shows protective effects against ISO-induced myocardial necrosis in rats. Effects of orally administered single doses of D-003 (25-400 mg/kg) and acetylsalicylic acid (ASA, 30 mg/kg), as well as repeated doses of D-003 (5-200 mg/kg), on characteristic markers of ISO-induced myocardial necrosis in rats were investigated. D-003 administered as single doses dose-dependently decreased necrosis area, percent of infarct area, and the presence of polymorphonuclear cells (PMNs) in myocardial tissue, but only the reductions induced by 200 and 400 mg/kg were significant. Oral acute treatment with ASA also decreased necrosis area and percent of infarct area, but the occurrence of PMNs was unchanged. D-003 administered repeatedly for 10 days also decreased all myocardial necrosis indicators in a dose-dependent manner, with results effective from 25 mg/kg to the highest dose tested, indicating that the repeated dose scheme was more effective to prevent the damage. It is concluded that D-003 shows a protective effect on the myocardial necrosis induced by ISO in rats.

Antioxidant Potential of a Novel Tetrapeptide Derivative in Isoproterenol-Induced Myocardial Necrosis in Rats

A novel tetrapeptide derivative Boc-Lys(Boc)-Arg-Asp-Ser(tbu)-OtBu (PEP1261) has been tested in vivo in isoproterenol (ISO) hydrochloride (HCl)-induced myocardial necrosis in rats. ISO·HCl induces myocardial necrosis in rats which is accompanied by the distinct increase in heart weight, marked electrocardiographic changes, increase in the levels of serum marker enzymes and lipid peroxides and decrease in the levels of antioxidants. PEP1261 (5 mg/kg body weight i.p.) pre- and post-treatment effectively decreases serum marker enzyme levels, while the electrocardiographic changes get restored towards normalcy. PEP1261 also inhibits the action of the free radicals toxicity by increasing the levels of antioxidants and histological studies confirm the above findings. This study shows that PEP1261 could serve as an excellent cardioprotective agent possessing membrane-stabilizing action.

Food Restriction Protects and Obesity Increases Vulnerability to Isoproterenol-Induced Myocardial Necrosis in Rats

Factors that determine the wide variation in the severity of isoproterenol-induced myocardial necrosis (ISO-MN) are numerous and poorly defined. We have investigated the role of age, body weight, food intake, and genetic strain differences on vulnerability to ISO-MN in rats. The proportion of apical myocardium that became necrotic after administration of toxic doses of isoproterenol was used as the index of ISO-MN. Sprague-Dawley (SD) rats of 8 to 10 and 16 to 18 weeks of age had 3.4 and 3.3 fold more severe apical myocardial lesions respectively than 5- to 6-week-old rats. Among Zucker rats of 8 to 9 weeks of age there was 5.2 times more necrosis in obese than in lean animals. Fifty percent food restriction for one week, or 24 hours of fasting in 8- to 10-week-old SD rats led to a 50% reduction in the area of necrosis compared to ad lib fed controls. Under similar conditions 16- to 18-week-old rats showed a similar reduction with 24-hour fasting, but 50% food restriction had no effect. Similarly, food restriction had no effect in 5- to 6-week-old SD or obese Zucker rats. Feeding of diets containing lard, or olive, corn, or fish oils for one week had no significant effect on ISO-MN in SD rats. These results suggests that age, obesity, and food intake alter vulnerability to ISO-MN.

Progressive ventricular remodeling in response to diffuse isoproterenol-induced myocardial necrosis in rats.

The purpose of the present study was to gain a better understanding of the relation between ventricular remodeling and heart failure by assessing the adaptation of the heart through time to graded myocardial injury in the presence of a patent coronary circulation. Left ventricular (LV) remodeling is a dynamic response of the heart to injury and a critical component in the development of heart failure. However, most previous studies have been in the presence of an occluded coronary vessel, which may in itself effect remodeling. Male Wistar rats received two subcutaneous injections of either 0, 85, 170, or 340 mg isoproterenol per kilogram of body weight. At 2, 6, and 16 weeks after injection, LV pressure, the pressure-volume relation, and histology were assessed. The graded myocardial necrosis produced in isoproterenol-treated rats was associated with dose-dependent increases in LV end-diastolic pressure, volume indexes, and global diastolic wall stress. In the higher dose groups, the LV continued to enlarge after 2 weeks, resulting in a further reduction in the ratio of LV mass to volume and a persistent rise in diastolic wall stress. These progressive changes in LV structure were associated with an increase in long-term mortality in rats from the intermediate- and high-isoproterenol dose groups. The present study in rats demonstrates that diffuse isoproterenol-induced myocardial necrosis results in a progressive enlargement of the LV cavity that is out of proportion to mass, a finding similar to that observed in discrete myocardial infarction.

Time course of Na, K-ATPase activity during development of isoproterenol-induced myocardial necrosis in rats

Time course of Na, K-ATPase activity during development of isoproterenol-induced myocardial necrosis in rats

Excitation-contraction coupling in heart. XII. Subcellular calcium transport in isoproterenol-induced myocardial necrosis

Calcium transport by cardiac subcellular particles in isoproterenol-induced myocardial necrosis in rats and rabbits was investigated. The ability of mitochondria to bind and accumulate calcium in the necrotic heart was similar to that of the control. Calcium binding, but not calcium uptake, by heavy microsomes of the necrotic heart was found to be depressed. This change in calcium was apparent over a wide pH range as well as at various concentrations of calcium in the incubation medium. The decrease in calcium binding by heavy microsomes was not due to the efflux of calcium from the microsomal vesicles and was seen within 1 hr of the subcutaneous injection of isoproterenol. At an increased animal room ambient temperature, not only was mortality due to isoproterenol injection increased, but also a decrease in the calcium uptake by heavy microsomes of the surviving animals was observed. These results suggest an alteration in the regulatory mechanisms responsible for the control of intracellular calcium in the necrotic heart.

Reduced myocardial fibrosis after dimethylsulfoxide (DMSO) treatment of isoproterenol-induced myocardial necrosis in rats.

Reduced myocardial fibrosis after dimethylsulfoxide (DMSO) treatment of isoproterenol-induced myocardial necrosis in rats.