Cardioprotective effect of lemon grass as evidenced by biochemical and histopathological changes in experimentally induced cardiotoxicity

Isoproterenol is a synthetic catecholamine found to cause toxicity leading to severe stress in the myocardium of experimental animals. The aim of the present study is to evaluate the cardioprotective effect of Cymbopogon citratus, which is used as a culinary item and commonly known as lemon grass (LG), in isoproterenol-induced cardiotoxicity. Male Wistar albino rats were segregated into five different groups as follows. Groups I and II rats were treated with vehicle. Groups III and IV rats were treated with 100 and 200 mg/kg b.wt. of LG. Group V with 100 mg/kg b.wt. of vitamin E. Myocardial necrosis was induced in Groups II, III, IV and V on 58(th) and 59(th) day using isoproterenol at a dose of 85 mg/kg twice at 24-hour interval. Animals were sacrificed on the 60( th) day. LG pretreatment exhibited cardioprotective activity as evidenced by decreased activity of cardiac markers in serum and increased the same in heart homogenate (p < 0.05). LG administration decreased the toxic events of lipid peroxidation (TBARS) in both serum and heart tissue, by increasing the level of enzymatic antioxidants and non-enzymatic antioxidants significantly in both heart homogenate and serum sample (p < 0.05). The histopathological observations also revealed that the cardioprotective effect of LG extract was observed at a dose of 200 mg/kg b.wt. The results of the present study reveal that LG is cardioprotective and antilipid peroxidative by increasing various antioxidants at a dose of 200 mg/kg b.wt., which is comparable with that of vitamin E.     

Protective role of curcumin in myocardial oxidative damage induced by isoproterenol in rats

This study was designed to investigate the effect of oral curcumin pretreatment (200 mg/kg) on isoproterenol-induced myocardial injury in rats. Isoproterenol (85 mg/kg, s.c., in two divided doses at 24 h intervals) administration induced a statistically significant increase (P < 0.01) in serum lactate dehydrogenase, creatine kinase, aspartate transaminase, and alanine transaminase activities and significant increase (P < 0.01) in myocardial lipid peroxides levels as compared to vehicle control rats. Furthermore, significant depletion (P < 0.01) of myocardial endogenous antioxidants viz. superoxide dismutase, catalase, and tissue glutathione levels were also found in the pathogenic control group, that is, isoproterenol only treated animals. Curcumin (200 mg/kg) pretreatment for 20 days in isoproterenol treated rats significantly lowered (P < 0.01) the serum lactate dehydrogenase, creatine kinase, aspartate transaminase, alanine transaminase, and myocardial lipid peroxides levels and increased the levels of myocardial endogenous antioxidants (superoxide dismutase, catalase, and tissue glutathione) as compared to pathogenic control rats. Furthermore, histological examination of rat's heart section confirmed myocardial injury with isoproterenol administration and near normal pattern with curcumin pretreatment. The results of our study provide clear evidence that the curcumin pretreatment enhances the antioxidant defense against isoproterenol-induced oxidative myocardial injury in rats and exhibit cardioprotective property.     

Effect of ginsenoside Rh1 on myocardial injury and heart function in isoproterenol-induced cardiotoxicity in rats

The present study was designed to investigate the effect of ginsenoside Rh1 on myocardial injury and heart function in isoproterenol-induced cardiotoxicity in rats. Sprague-Dawley rats were subcutaneously injected with isoproterenol (20?mg/kg). Cardiac marker enzymes in serum, antioxidative parameters and inflammatory cytokines in left ventricles were measured. Hemodynamic parameters were monitored and recorded as well. Histopathological examination of left ventricles was performed. It was found that creatine kinase-MB (CK-MB) activity and troponin T level in isoproterenol-treated rats were significantly increased. Isoproterenol caused declines of left ventricular systolic pressure, positive and negative maximal values of the first derivative of left ventricular pressure, and an elevation of left ventricular end diastolic pressure. Isoproterenol enhanced the content of malondialdehyde (MDA), tumor necrosis-α (TNF-α), interleukin-1β (IL-1β) and decreased the activities of superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH-Px) in left ventricles. Ginsenoside Rh1 significantly ameliorated myocardial injury and heart function impairment induced by isoproterenol. The cardioprotective effect of ginsenoside Rh1 was further confirmed by histopathological examination. Ginsenoside Rh1 also partially inhibited the increase of MDA, TNF-α, IL-1β contents and the decrease of SOD, catalase, and GSH-Px activities in left ventricles. The results indicated that ginsenoside Rh1 possessed the effect against isoproterenol-induced cardiotoxicity, and that the mechanism of pharmacological action was related to regulating the activities of SOD, catalase, and GSH-Px and decreasing the contents of TNF-α and IL-1β.     

Effect of ginsenoside Rh1 on myocardial injury and heart function in isoproterenol-induced cardiotoxicity in rats

The present study was designed to investigate the effect of ginsenoside Rh1 on myocardial injury and heart function in isoproterenol-induced cardiotoxicity in rats. Sprague–Dawley rats were subcutaneously injected with isoproterenol (20?mg/kg). Cardiac marker enzymes in serum, antioxidative parameters and inflammatory cytokines in left ventricles were measured. Hemodynamic parameters were monitored and recorded as well. Histopathological examination of left ventricles was performed. It was found that creatine kinase-MB (CK-MB) activity and troponin T level in isoproterenol-treated rats were significantly increased. Isoproterenol caused declines of left ventricular systolic pressure, positive and negative maximal values of the first derivative of left ventricular pressure, and an elevation of left ventricular end diastolic pressure. Isoproterenol enhanced the content of malondialdehyde (MDA), tumor necrosis-α (TNF-α), interleukin-1β (IL-1β) and decreased the activities of superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH-Px) in left ventricles. Ginsenoside Rh1 significantly ameliorated myocardial injury and heart function impairment induced by isoproterenol. The cardioprotective effect of ginsenoside Rh1 was further confirmed by histopathological examination. Ginsenoside Rh1 also partially inhibited the increase of MDA, TNF-α, IL-1β contents and the decrease of SOD, catalase, and GSH-Px activities in left ventricles. The results indicated that ginsenoside Rh1 possessed the effect against isoproterenol-induced cardiotoxicity, and that the mechanism of pharmacological action was related to regulating the activities of SOD, catalase, and GSH-Px and decreasing the contents of TNF-α and IL-1β.     

Ellagic acid ameliorates isoproterenol induced oxidative stress: Evidence from electrocardiological, biochemical and histological study

The present study was designed to evaluate the cardioprotective effects of ellagic acid against isoproterenol induced myocardial infarction in rats by studying electrocardiography, blood pressure, cardiac markers, lipid peroxidation, antioxidant defense system and histological changes. Male Wistar rats were treated orally with ellagic acid (7.5 and 15 mg/kg) daily for a period of 10 days. After 10 days of pretreatment, isoproterenol (100 mg/kg) was injected subcutaneously to rats at an interval of 24 h for 2 days to induce myocardial infarction. Isoproterenol administered rats showed significant changes in the electrocardiogram pattern, arterial pressure, and heart rate. Isoproterenol-induced rats also showed significant (P < 0.05) increase in the levels of serum troponin-I, creatine kinase, lactate dehydrogenase, C-reactive protein, plasma homocysteine, heart tissue thiobarbituric acid reactive substances and lipid hydro peroxides. The activities/levels of antioxidant system were decreased in isoproterenol-induced rats. The histopathological findings of the myocardial tissue evidenced myocardial damage in isoproterenol induced rats. The oral pretreatment of ellagic acid restored the pathological electrocardiographic patterns, regulated the arterial blood pressures and heart rate in the isoproterenol induced myocardial infarcted rats. The ellagic acid pretreatment significantly reduced the levels of biochemical markers, lipid peroxidation and significantly increased the activities/levels of the antioxidant system in the isoproterenol induced rats. An inhibited myocardial necrosis was evidenced by the histopathological findings in ellagic acid pretreated isoproterenol induced rats. Our study shows that oral pretreatment of ellagic acid prevents isoproterenol induced oxidative stress in myocardial infarction.     

Mechanisms of cardioprotective effect of Withania somnifera in experimentally induced myocardial infarction

The present study was designed to evaluate the cardioprotective potential of hydro-alcoholic extract of Withania somnifera on the basis of haemodynamic, histopathological and biochemical parameters in the isoprenaline-(isoproterenol) induced myocardial necrosis in rats and to compare with Vitamin E, a known cardioprotective antioxidant. Wistar albino male rats (150-200 g) were divided into six main groups: sham, isoprenaline control, Withania somnifera/Vitamin E control and Withania somnifera/Vitamin E treatment groups. Withania somnifera was administered at doses 25, 50 and 100 mg/kg and Vitamin E at a dose of 100 mg/kg, orally for 4 weeks. On days 29 and 30, the rats in the isoprenaline control and Withania somnifera/Vitamin E treatment groups were given isoprenaline (85 mg/kg), subcutaneously at an interval of 24 hr. On day 31, haemodynamic parameters were recorded and the hearts were subsequently removed and processed for histopathological and biochemical studies. A significant decrease in glutathione (P<0.05), activities of superoxide dismutase, catalase, creatinine phosphokinase and lactate dehydrogenase (P<0.01) as well as increase in lipid peroxidation marker malonyldialdehyde level (P<0.01) was observed in the hearts of isoproterenol control group rats as compared to sham control. However, we have not observed any significant changes in activity of glutathione peroxidase and protein levels. Left ventricular dysfunction was seen as a decrease in heart rate, left ventricular rate of peak positive and negative pressure change and elevated left ventricular end-diastolic pressure in the control group was recorded. On histopathological examination, myocardial damage was further confirmed. Our data show that Withania somnifera (25, 50 and 100 mg/kg) exerts a strong cardioprotective effect in the experimental model of isoprenaline-induced myonecrosis in rats. Augmentation of endogenous antioxidants, maintenance of the myocardial antioxidant status and significant restoration of most of the altered haemodynamic parameters may contribute to its cardioprotective effect. Among the different doses studied, Withania somnifera at 50 mg/kg dose produced maximum cardioprotective effect.     

Effect of alpha-tocopherol on lipid peroxidation in isoproterenol induced myocardial infarction in rats

The effect of alpha-tocopherol pretreatment on lipid peroxidation and antioxidant status in isoproterenol induced myocardial infarction was studied in rats. Isoproterenol administered rats showed a significant increase in lipid peroxides in serum, heart and aorta. A significant increase in serum iron level with a significant decrease in iron binding capacity was also observed. The levels of antioxidants such as ceruloplasmin, glutathione and the activities of antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase decreased significantly in isoproterenol administered rats when compared to control. The activity of Na+K+ATPase decreased significantly and the activity of Ca2+ATPase increased significantly in heart and aorta of isoproterenol administered rats. alpha-tocopherol pretreated rats maintained the levels of antioxidants, membrane bound enzymes and activities of antioxidant enzymes near normal, on isoproterenol administration, thus establishing its effect as an antioxidant.     

Cardioprotective effect of matrine on isoproterenol‐induced cardiotoxicity in rats

Objectives This study was designed to explore the effect and mechanism of matrine, an active component of Chinese traditional medicine, on isoproterenol‐induced acute cardiotoxicity in rats. Methods Acute myocardial injury was induced in rats by daily subcutaneous injection of isoproterenol (85 mg/kg) for two days. Haemodynamic and biochemical parameters were measured and histopathological examination was performed. Key findings Chronic oral administration of matrine (50, 100 or 200 mg/kg per day for 10 days) significantly reduced the release of lactic dehydrogenase, glutamic oxaloacetic transaminase and creatine kinase after isoproterenol‐induced myocardial ischaemic injury, improved the left ventricular (LV) dysfunction, including increased LV systolic pressure (LVSP), maximum rate of developed LV pressure (LV dP/dt_max) and minimum rate of developed LV pressure (LV dP/dt_min), increased the activity of superoxide dismutase, catalase and glutathione peroxidase, and also decreased the content of the lipid peroxidation product malondialdehyde in plasma and myocardial tissues in rats. Acute oral administration of matrine at a dose of 100 or 200 mg/kg for two days also had a cardioprotective effect on this rat model. The protective role of matrine on isoproterenol‐induced myocardial damage was further confirmed by histopathological examination. There were no significant changes in heart rate and blood pressure in all experimental groups. Conclusions Our results suggest that matrine has a significant cardioprotection against isoproterenol‐induced cardiotoxicity through its antioxidant property.     

Effect of ethanol extract of Embelia ribes fruits on cardiac changes in rats subjected to ischemic reperfusion injury

The present study evaluated the cardioprotective potential of ethanol extract of Embelia ribes Burm. (Myrsinaceae) fruits on left anterior descending coronary artery ligation (LAD)-induced myocardial infarction in albino rats. In open-chest chloral hydrate (400?mg/kg, i.p.) anesthetized rats, the left anterior descending coronary artery was occluded for 30?min followed by 90?min of reperfusion. Vehicle (1% Tween 80 in distilled water) or ethanol Embelia ribes extract (100 and 200?mg/kg, orally) was administered for 7 days (pre-treatment). In the vehicle-treated group, ischemic-reperfusion injury (IRI) was evidenced by depression of hemodynamic function (heart rate), raised levels of serum lactate dehydrogenase (LDH) and myocardial thiobarbituric acid reactive substances (TBARS) levels and depletion of endogenous myocardial antioxidants (glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST)) and Na-K-ATPase levels, as compared to sham rats. Pre-treatment with ethanol Embelia ribes extract prevented 1) loss of myocardial hemodynamic function, 2) rise in serum LDH and myocardial TBARS levels, and 3) depletion of myocardial endogenous antioxidants and Na-K-ATPase levels. The results of the present study, suggests that ethanol Embelia ribes extract treatment enhances the antioxidant defense against LAD-induced ischemic-reperfusion injury in rats and exhibits cardioprotective property.     

Effect of Piper betle on cardiac function,marker enzymes,and oxidative stress in isoproterenol-induced cardiotoxicity in rats

The present study was designed to investigate the cardioprotective potential of Piper betle (P. betle) against isoproterenol (ISP)-induced myocardial infarction in rats. Rats were randomly divided into eight groups viz. control, ISP, P. betle (75, 150, and 300?mg/kg) and P. betle (75, 150, and 300?mg/kg) + ISP treated group. P. betle leaf extract (75, 150, or 300?mg/kg) or saline was orally administered for 30 days. ISP (85?mg/kg, s.c.) was administered at an interval of 24?h on the 28^th and 29^th day and on day 30 the functional and biochemical parameters were measured. ISP administration showed a significant decrease in systolic, diastolic, mean arterial pressure (SAP, DAP, MAP), heart rate (HR), contractility (+LVdP/dt), and relaxation (?LVdP/dt) and increased left ventricular end-diastolic pressure (LVEDP). ISP also caused significant decrease in myocardial antioxidants; superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), and myocyte injury marker enzymes; creatine phosphokinase-MB (CK-MB) isoenzyme and lactate dehydrogenase (LDH) along with enhanced lipid peroxidation; thiobarbituric acid reacting species (TBARS) in heart. Pre-treatment with P. betle favorably modulated hemodynamic (SAP, DAP, and MAP) and ventricular function parameters (?LVdP/dt and LVEDP). P. betle pre-treatment also restored SOD, CAT, GSH, and GPx, reduced the leakage of CK-MB isoenzyme and LDH along with decreased lipid peroxidation in the heart. Taken together, the biochemical and functional parameters indicate that P. betle 150 and 300?mg/kg has a significant cardioprotective effect against ISP-induced myocardial infarction. Results of the present study suggest the cardioprotective potential of P. betle.     

Coconut kernel protein in diet protects the heart by beneficially modulating endothelial nitric oxide synthase,tumor necrosis factor-alpha,and nuclear factor-kappaB expressions in experimental myocardial infarction

Previous studies conducted in our laboratory revealed that coconut kernel protein has a significant cardioprotective effect on isoproterenol-induced myocardial infarction in rats. In the present study, we explored the possible protective mechanism of coconut kernel protein during acute myocardial infarction. Coconut kernel protein (50 mg/100 g) was administered to Sprague-Dawley rats orally for 45 days. Isoproterenol (20 mg/100 g) was injected subcutaneously at an interval of 24 hours twice to induce myocardial infarction. Myocardial infarction was confirmed by the abnormal activities of cardiac marker enzymes in serum. Activities of antioxidant enzymes such as superoxide dismutase (SOD) and catalase were decreased (p < 0.05) in the heart of isoproterenol-treated rats, whereas pretreatment with coconut kernel protein increased (p < 0.05) these activities. An improved antioxidant status in these rats was further confirmed by the increased level of reduced glutathione and decreased level of lipid peroxidation products. Nitric oxide synthase (NOS) activity in the heart and nitrite level in blood were increased (p < 0.05) in coconut kernel protein-treated rats administered with isoproterenol compared to isoproterenol control rats. Coconut protein pretreatment upregulated the expression of endothelial nitric oxide synthase (eNOS), whereas expressions of nuclear factor-kappaB (NF-κB) and tumor necrosis factor-alpha (TNF-α) were downregulated in isoproterenol-treated rats. These findings suggest that the protective effects of coconut kernel protein may be mediated in part through upregulation of nitric oxide production, antioxidant mechanisms, and its ability to inhibit TNF-α and NF-κB activation.     

Ventricular repolarization in a rat model of global heart failure

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Curcumin attenuation of acute adriamycin myocardial toxicity in rats

The protective effect of curcumin on acute adriamycin (ADR) myocardial toxicity was analysed in rats. ADR toxicity, induced by a single intraperitoneal injection (30 mg kg⁻¹), was revealed by elevated serum creatine kinase (CK) and lactate dehydrogenase (LDH). The level of the lipid peroxidation products, conjugated dienes and malondialdehyde, was markedly elevated by ADR. ADR caused a decrease in myocardial glutathione content and glutathione peroxidase activity. In contrast, cardiac catalase activity was increased in ADR rats. Curcumin treatment (200 mg kg⁻¹, seven days before and two days following ADR) significantly ameliorated the early manifestation of cardiotoxicity (ST segment elevation and an increase in heart rate) and prevented the rise in serum CK and LDH exerted by ADR. ADR rats that received curcumin displayed a significant inhibition of lipid peroxidation and augmentation of endogenous antioxidants. These results suggest that curcumin inhibits ADR cardiotoxicity and might serve as novel combination chemotherapeutic agent with ADR to limit free radical-mediated organ injury.     

Protective effect of Artemisia afra Jacq. on isoproterenol-induced myocardial injury in Wistar rats

Artemisiaafra Jacq. ex Willd. is a widely used medicinal plant in South Africa for the treatment of various diseases. In this study, the effect of the herb on isoproterenol (ISO)-induced myocardial injury in rats was investigated. Pretreatment with the aqueous leaf extract of the plant at 100 and 200 mg/kg body weight for 30 days prevented the elevation of serum marker enzymes namely lactate dehydrogenase (LDH), aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP) in myocardial injured rats. ISO-induced animals exhibited decreased levels of glutathione reductase (GR), glutathione peroxides (GPx), superoxide dismutase (SOD) and glutathione (GSH) in the heart, which were restored to near normal levels following treatment with the herb. The extract also attenuated lipid peroxidation (LPO) in the heart and improved the imbalance in lipid profile caused by ISO. The effect was more prominent at 200 mg/kg body weight. These findings revealed the cardioprotective effect of A. afra against isoproterenol-induced myocardial injury.     

Ameliorative effect of naringin against doxorubicin-induced acute cardiac toxicity in rats

Context: Doxorubicin (Dox) is one of the most active chemotherapeutic agents used to treat various types of cancers. Its clinical utility is compromised due to fatal cardiac toxicity characterized by an irreversible cardiomyopathy.

Objective: This study evaluates the cardioprotective potential of naringin (NR) against Dox-induced acute cardiac toxicity in rats.

Materials and methods: Male Wistar rats were randomly divided into five groups. NR (50 and 100?mg/kg) was administered intraperitoneally (i.p.) daily from 0 to 14?d. Doxorubicin (15?mg/kg, i.p.) was given as a single dose on the 10th day. On the 14th day, all animals were sacrificed and oxidative stress parameters that include malondialdehyde (MDA), glutathione (GSH) level, superoxide dismutase (SOD), catalase (CAT) activities, and all mitochondrial complexes (I-IV) activities were evaluated along with histopathological studies of the heart.

Results: Doxorubicin-induced cardiotoxicity was confirmed by increased (p?<?0.05) MDA, decreased (p?<?0.05) GSH levels, SOD, and CAT activities, mitochondrial complexes (I–IV) activities in the heart tissue. NR (100?mg/kg) showed cardioprotection as evident from significant decreased MDA (p?<?0.001) level, raised (p?<?0.001) GSH level, SOD and CAT activities and increased mitochondrial complexes I (p?<?0.01), II (p?<?0.001), III (p?<?0.001), and IV (p?<?0.05) activities. Further, Dox-induced cardiotoxicity was confirmed by histopathological studies. These obtained results indicated the protective role of NR against Dox-induced cardiac toxicity in rats.

Conclusion: NR can be used in combination with Dox due to its high cardioprotective effect against Dox-induced cardiomyopathy.     

Seabuckthorn attenuates cardiac dysfunction and oxidative stress in isoproterenol-induced cardiotoxicity in rats

We investigated the effects of seabuckthorn (SBT) oil in isoproterenol (ISO)-induced cardiotoxicity with reference to hemodynamic, antioxidant, histopathological, and ultrastructural parameters. Rats were administered SBT oil (5, 10, and 20 mL/kg per d) or vehicle orally for 30 days along with ISO (85 mg/kg, subcutaneously, at 24-hour interval) on 29th and 30th day. On 31st day, ISO control rats showed cardiac dysfunction, increased lipid peroxidation, depletion of cardiac injury marker enzymes, and antioxidant activities. Myocardial necrosis, edema, and inflammation were evident from the light microscopic and ultrastructural changes. Seabuckthorn oil at the dose of 20 mL/kg per d significantly modulates hemodynamic and antioxidant derangements. The preventive role of SBT oil on ISO-induced cardiotoxicity was reconfirmed by histopathological and ultrastructural examinations. Thus, the present study reveals that SBT oil mitigates myocardial damage in ISO-induced cardiac injury in rats by maintaining hemodynamic, biochemical, histopathological, and ultrastructural perturbations owing to its free radical scavenging and antioxidant activities.     

Preventive effect of naringin on lipid peroxides and antioxidants in isoproterenol-induced cardiotoxicity in Wistar rats: biochemical and histopathological evidences

This study was designed to evaluate the cardioprotective potential of naringin on lipid peroxides, enzymatic and nonenzymatic antioxidants and histopathological findings in isoproterenol (ISO)-induced myocardial infarction (MI) in rats. Subcutaneous injection of ISO (85 mg/kg) to male Wistar rats showed a significant increase in the levels of thiobarbituric acid reactive substances and lipid hydroperoxides in plasma and the heart and a significant decrease in the activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase in the heart and the levels of reduced glutathione, vitamin C and vitamin E in plasma and heart and ceruloplasmin in plasma. Oral administration of naringin (10, 20 and 40 mg/kg, respectively) to ISO-induced rats daily for a period of 56 days showed a significant decrease in the levels of lipid peroxidative products and improved the antioxidant status by increasing the activities of antioxidant enzymes and nonenzymatic antioxidants. Histopathological findings of the myocardial tissue showed the protective role of naringin in ISO-induced rats. The effect at a dose of 40 mg/kg of naringin was more pronounced than that of the other two doses, 10 and 20mg/kg. The results of our study show that naringin possess anti-lipoperoxidative and antioxidant activity in experimentally induced cardiac toxicity.     

Chronic beta-adrenoceptor stimulation and cardiac hypertrophy with no induction of circulating renin

The hemodynamic and cardiac effects of isoproterenol were examined in rats submitted to chronic salt loading (1% NaCl as drinking water) to prevent activation of the systemic renin–angiotensin system. Isoproterenol treatment for 1 week resulted in 36% and 44% (P < 0.05) increase in left ventricle mass in both control and chronic salt loading rats and induction of cardiac angiotensin-converting enzyme activity and expression (P < 0.05) with no changes in serum angiotensin-converting enzyme. Plasma renin activity decreased significantly with chronic salt loading and failed to increase by isoproterenol treatment, whereas it increased 2.33 fold (P < 0.05) in animals kept on regular chow. Isoproterenol treatment leads to transient increase in heart rate and cardiac output while blood pressure remained unchanged. Altogether, these data provide evidence that isoproterenol induced hypertrophy is associated with cardiac induction of angiotensin-converting enzyme and daily transient hemodynamic overload even in the absence of systemic activation of renin–angiotensin system.     

A biochemical, electrocardiographic, electrophoretic, histopathological and in vitro study on the protective effects of (-)epicatechin in isoproterenol-induced myocardial infarcted rats

(-) Epicatechin rich foods and (-) epicatechin improve cardiovascular function. Consumption of diets rich in flavonoids is associated with reduced risk of cardiovascular diseases. Oxidative stress resulting from increased production of free radicals associated with decreased levels of antioxidants in the myocardium plays a major role in the pathogenesis of myocardial infarction. This study aims to evaluate the preventive effects of (-) epicatechin on oxidative stress in isoproterenol-induced myocardial infarcted rats. Male Wistar rats were pretreated with (-) epicatechin (20mg/kg body weight) daily for 21 days. After pretreatment, isoproterenol (100mg/kg body weight) was injected into the rats at an interval of 24h for two days to induce myocardial infarction. Isoproterenol induced rat's electrocardiogram showed elevated ST segments and significant increase in the activity of serum creatine kinase-MB, level of serum troponin-T and increased intensities of serum lactate dehydrogenase 1 and 2-isoenzymes. The rats also showed significant increased levels of heart lipid peroxidation products and significant decreased activities of heart superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and levels of reduced glutathione. Pretreatment with (-) epicatechin revealed significant protective effects on all the biochemical parameters and electrocardiogram investigated. Histopathology of myocardium confirmed the present findings. The in vitro study on the effects of (-) epicatechin on scavenging free radical 1,1-diphenyl-2-picrylhydrazyl revealed the free radical scavenging potential of (-) epicatechin. Thus, (-) epicatechin exerts protective effects against isoproterenol-induced oxidative stress thereby reducing cardiac tissue damage by its free radical scavenging and antioxidant effects.     

Regulation of endothelial nitric oxide synthase and asymmetric dimethylarginine by matrine attenuates isoproterenol-induced acute myocardial injury in rats

Objectives This study was designed to investigate the cardioprotective effects of matrine on regulation of endothelial nitric oxide synthase (eNOS) and asymmetric dimethylarginine (ADMA) in isoproterenol‐induced acute myocardial ischaemic rats. Methods Male Sprague–Dawley rats were pretreated with matrine (200, 100 and 50 mg/kg) orally for 10 days. Acute myocardial injury was induced in rats by subcutaneous injection of isoproterenol. Serum and haemodynamic parameters, histopathological variables and expression of protein levels were analysed. Key findings Oral administration of matrine (200, 100 and 50 mg/kg) significantly attenuated isoproterenol‐induced cardiac necrosis and left ventricular dysfunction. Matrine treatment restored impaired ventricular Akt and eNOS protein expression with concomitant increased phosphorylation of Akt (Ser473) and eNOS (Ser1177), and also restored glycogen synthase kinase 3β activity, as indicated by increased phosphorylation at Ser 9. Moreover, treatment with matrine had no effect on the isoproterenol‐induced elevated protein arginine methyltransferase 1 protein expression, but could significantly normalize the reduced dimethylarginine dimethylaminohydrolase 2 expression and attenuate the increased serum level of ADMA. The expression of catechol‐o‐methyltransferase and monoamine oxidase did not differ among all groups (all P > 0.05). Conclusions Our results suggested that matrine protects against isoproterenol‐induced myocardial ischaemia via eNOS and ADMA pathway.