Inhibitors of soluble epoxide hydrolase minimize ischemia-reperfusion-induced cardiac damage in normal, hypertensive, and diabetic rats

AIM

We designed a study to evaluate the cardioprotective effect of two soluble epoxide hydrolase (sEH) inhibitors, 1-(1-propanoylpiperidin-4-yl)-3-(4-trifluoromethoxy)phenyl)urea (TPPU) and trans-4-{4-[3-(4-trifluoromethoxyphenyl)-ureido]cyclohexyloxy}benzoic acid (t-TUCB), in ischemia-reperfusion (IR) model.

METHODS

Cardioprotective effects of the sEH inhibitors were evaluated against IR-induced myocardial damage in hearts from normal, hypertensive, and diabetic rats using Langendorff's apparatus. In addition, the effect of sEH inhibitors on endothelial function was evaluated in vitro and ex vivo using isolated rat thoracic aorta.

RESULTS

Ischemia-reperfusion (IR) increased the myocardial damage in hearts from normal rats. IR-induced myocardial damage was augmented in hearts isolated from hypertensive and diabetic rats. Myocardial damage as evident from increase in the activities of lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) in heart perfusate was associated with significant decrease in the heart rate and developed tension, and increase in the resting tension in isolated heart. Both sEH inhibitors protected the heart in normal, hypertensive, and diabetic rats subjected to IR injury. The sEH inhibitor t-TUCB relaxed phenylephrine precontracted aorta from normal rats. Relaxant effect of acetylcholine (ACh) was reduced in aortas from diabetic and hypertensive rats compared to normal rats. Pretreatment of sEH inhibitors to diabetic and hypertensive rats increased relaxant effect of ACh on aortas isolated from these rats.

CONCLUSIONS

Prophylactic treatment with sEH inhibitors decreased myocardial damage due to IR, hypertension and diabetes, and decreased endothelial dysfunction created by diabetes and hypertension. Therefore, inhibitors of sEH are useful probes to study cardiovascular pathology, and inhibition of the sEH is a potential approach in the management of IR-induced cardiac damage and endothelial dysfunction-related cardiovascular disorders.

Effect of Cinnamomum cassia methanol extract and sildenafil on arginase and sexual function of young male Wistar rats

INTRODUCTION

Herbs have been used as an aphrodisiac since ages. Cinnamomum cassia is an important ingredient of many Ayurvedic formulations to treat male sexual disorder including erectile dysfunction (ED).

AIM

The objective of the present study was to evaluate erectogenic and aphrodisiac activity of methanol extract of C. cassia bark in young male rats.

METHODS

Methanol extract of C. cassia was screened in vitro for arginase inhibition potential and IC50 was determined. Effect of the extract was observed in vitro on phenylephrine pre-contracted isolated rat corpus cavernosum smooth muscle (CCSM) at 0.1, 1, 10, and 100 μg/mL. Young male Wistar rats were dosed with extract at 100 mg/kg body weight for 28 days and its effects on sexual behavior and penile smooth muscle : collagen level were observed.

MAIN OUTCOME MEASURE

Effect of C. cassia was studied on arginase activity in vitro and sexual behavior of young male rats.

RESULTS

C. cassia inhibited arginase activity in vitro with an IC50 of 61.72 ± 2.20 μg/mL. The extract relaxed phenylephrine pre-contracted isolated rat CCSM up to 43% and significantly increased (P < 0.05) sexual function of young male rats. Treatment with the extract also increased smooth muscle level and decreased collagen level in rat penile tissue.

CONCLUSION

The study proves usefulness of methanol extract of C. cassia bark for increasing sexual function.

Potential of garlic and its active constituent, S-allyl cysteine, as antihypertensive and cardioprotective in presence of captopril

The purpose of the present study was to investigate the role of fresh garlic homogenate (FGH) and its bioactive sulphur compound S-allyl cysteine sulphoxide (SACS) in potentiating antihypertensive and cardioprotective activities of captopril in rats. SACS was extracted from the fresh garlic using ion exchange resins with yield of 890 mg/kg garlic. The dose of SACS was calculated based on the amount of SACS extracted from 125 to 250 mg of FGH. Albino rats weighing 150-200 g were fed with 10% fructose in fluid for 3 weeks for induction of hypertension and subsequently administered FGH (125 and 250 mg/kg, p.o.) or SACS (0.111 and 0.222 mg/kg/day, p.o.) for the next 3 weeks in their respective groups. In CAP alone and interactive groups (GH+CAP; SACS+CAP), captopril 30 mg/kg was given during sixth week of 10% fructose in fluid. At the end of drug treatment, animals were given isoproterenol 175 mg/kg subcutaneously for two consecutive days. Additionally, varying concentrations of SACS (4, 8, 16, 32 and 64 ng), CAP (1, 2, 4, 8 and 16 ng) and their combination (4:1) were checked for fall in blood pressure in hypertensive rats (10% fructose in fluid without pretreatment) as well as angiotensin-converting enzyme (ACE) inhibiting activity using guinea pig ileum. An isobolographic analysis was used to characterise the interaction between SACS and CAP for fall in blood pressure and ACE inhibiting evaluations. Administration of captopril, low and high doses of FGH (125, 250 mg/kg), either alone or together showed fall in fluid intake and body weight. The combined therapy of FGH 250 mg/kg and CAP was more effective in reducing systolic blood pressure, cholesterol, triglycerides and glucose. The SOD and catalase activities in heart tissue were significantly elevated in groups treated with FGH, SACS, CAP, FGH+CAP and SACS+CAP. Further, combined therapy of FGH 250 mg/kg and CAP caused significant fall in LDH and CK-MB activities in serum and elevation in heart tissue homogenate. SACS in low dose was less effective than low dose of FGH; similarly, high dose of FGH was more efficacious than high dose of SACS. Corroborating with this, combined therapy of garlic (250 mg/kg) with CAP demonstrated higher synergistic action than combination of SACS (0.222 mg/kg) with CAP suggesting the role of additional bioactive constituents apart from SACS, responsible for therapeutic efficacy of garlic. Moreover, combination of SACS and CAP exerted super-additive (synergistic) interaction with respect to fall in blood pressure and ACE inhibition. This study may represent an advertence on concomitant use of garlic or its bioactive constituent, SACS, with captopril.

Comparative interaction of few antihypertensive drugs with cyclosporine-A in rats

The maximal endothelial dependent relaxation of isolated aortic rings to cumulative doses of acetylcholine was significantly decreased in the Cyclosporine-A (CSA, 20 mg kg(-1) day(-1)) treated animals compared to olive oil (CSA vehicle) treated control. Administration of antihypertensive drugs like diltiazem, enalapril or propranolol to CSA treated animals augmented the endothelial damage induced by CSA. These drugs also increased the bioavailability of CSA. However, administration of losartan to CSA treated animals produced a significant increase in endothelial dependent relaxation as compared to CSA treated control but did not affect the bioavailability of CSA significantly. The results suggest that losartan is safer compared to other antihypertensives for the treatment of CSA induced hypertension.