Angiotensin converting enzyme inhibitor potentiates the hypoglycaemic effect of NG-nitro-L-arginine methyl ester (L-NAME) in rats.

The inhibition of renin angiotensin system pathway has been largely documented to be effective in the control of cardiovascular events. The present study investigated the effect of angiotensin converting enzyme (ACE) inhibitor on fasting blood glucose level in hypertension induced by the inhibition of nitric oxide synthase (NOS) in male Wistar rats. Hypertension was induced by the inhibition of NOS using a non-selective NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME). The blockade of NOS resulted in an increase in blood pressure, ACE, angiotensin II and endothelin-1 levels, and a decrease in fasting blood glucose and nitric oxide (NO) levels. The hypertensive rats treated with ACE inhibitor (ramipril) recorded a decrease in blood pressure, ACE, angiotensin II, endothelin-1, NO and fasting blood glucose levels, and an increase in prostacyclin level. In conclusion, ACE inhibitor potentiated the hypoglycaemic effect of NOS inhibitor and this effect is independent of NO and pancreatic insulin release.

Anti-lipidemic Effect of Fractions of Peristrophe bivalvis Leaf in NG-nitro-L-arginine Methyl Ester (L-NAME) Treated Rats.

PURPOSE: The reduction in nitric oxide (NO) bioavailability accelerates atherosclerosis development, augments lipolysis, elevates blood pressure and upregulate leukocyte level. This study was designed to examine the biochemical constituents of fractions of Peristrophe bivalvis (PB) leaf, their effect on blood pressure, serum lipid contents and complete blood count in NG-nitro-L-arginine methyl ester (L-NAME) hypertensive rats. METHOD: Male Wistar rats were grouped into control and hypertensive groups. The hypertensive group was pretreated with 60 mg/kg b.w of L-NAME (L-NAME60) daily for two weeks. They were then randomly sub-grouped into: Hypertensive (H), Hypertensive+n-hexane fraction (HHF), Hypertensive+dichloromethane fraction (HDF), Hypertensive+ethyl acetate fraction (HEF) and Hypertensive+aqueous fraction (HAF) groups. These were orally gavaged with L-NAME60 and L-NAME60+200 mg/kg b.w of fractions of PB respectively, daily for two weeks. RESULT: The biochemical components analysis of the fractions of PB identified numerous polar and non polar compounds like alkaloids, organic acids and esters. The results showed a significant increase in NO level in HHF and HEF groups compared to H. Total cholesterol, triglyceride, low density lipoprotein cholesterol (LDL-C) and very LDL-C were significantly decreased in HAF group compared to H. High density lipoprotein cholesterol (HDL-C) increased significantly and atherogenic indices decreased significantly in HHF, HDF and HAF groups compared to H, while reduced glutathione level increased significantly in HHF group compared to H. White blood cells count effectively decreased in HEF group compared to H. CONCLUSION: In brief, the fractions of PB leaf increased HDL-C and NO, and decrease atherogenic indices in L-NAME treated rats.

Peristrophe roxburghiana leaf extracts exhibited anti-hypertensive and anti-lipidemic properties in L-NAME hypertensive rats.

AIMS: Hypertension is a global disease that has been combating the world health for ages. Peristrophe roxburghiana (PR) is used in traditional medicine to treat hypertension and other ailments. The present study examined phytochemical constituents, antioxidant activities and GC-MS analysis of extracts of PR leaf and also evaluated their anti-hypertensive and anti-lipidemic effects in NG-nitro-L-arginine methyl ester (L-NAME) hypertensive rats. METHODS: Wistar rats were grouped into two groups: control and hypertensive. Hypertension was induced in the hypertensive group by oral gavage of 60 mg/kg b.w of L-NAME for 3 weeks. After induction, the hypertensive group was randomly sub-grouped into hypertensive, hypertensive treated and hypertensive untreated groups. These were orally gavaged respectively with 60 mg/kg b.w of L-NAME, 60 mg/kg b.w/day of L-NAME +200 mg/kg b.w of different extracts of PR (aqueous, ethanolic and methanolic extracts) and 60 mg/kg b.w of L-NAME +20 mg/kg b.w ramipril for 3 weeks. The blood pressure was measured by tail-cuff method at the third and sixth weeks. KEY FINDINGS: The results showed that the extracts of PR significantly decrease blood pressure, pro-atherogenic lipids and atherogenic ratios in L-NAME hypertensive rats. White blood cells count, neutrophil count and creatinine level were also effectively decreased by the extracts. Furthermore, the extracts increase serum nitric oxide (NO) level, anti-atherogenic lipid, glutathione level, lymphocyte and platelet count in the rats. SIGNIFICANCE: Extracts of PR leaf decrease blood pressure and increase NO level in L-NAME hypertensive rats and also corrected the hyperlipidemia and inflammatory response arising from the reduction in NO bioavailability.

Reduction in nitric oxide bioavailability shifts serum lipid content towards atherogenic lipoprotein in rats.

Nitric oxide (NO) is major endothelial relaxing factor and reduction in its bioavailabilty has been linked to hypertension. Furthermore, high lipid content is a strong risk factor predisposing to cardiovascular diseases. The principal focus of this study was to investigate the effect of blockade of nitric oxide synthase (NOS) on serum lipid content in rats. Male Wistar rats (150-170 g, n = 15) were randomly divided into two groups designated control (n = 5), and L-Name group (n = 10) and were gavage with distilled water and 60 mg/kg of L-NAME respectively daily for three weeks. After 3 weeks, the L-NAME group was sub-divided into two sub-groups (n = 5 each): L-NAME (60 mg/kg of L-NAME), and L-NAME plus ramipril (LR) (60 mg/kg of L-NAME plus 20 mg/kg of ramipril) and were treated daily for another three weeks. The blood pressure (BP) of the conscious rats was measured by tail-cuff method at the onset, at the third and at the sixth weeks of the experiment; while serum lipid contents and NO were measured at the third and sixth weeks. At the end of the experiment blood sample was drawn by ocular puncture for evaluation of lipid profile and NO, and the animals were later euthanized by overdose of anaesthesia. Data were analyzed using ANOVA at p < 0.05. There was a significant increase in BP, triglyceride, total cholesterol, low density lipoprotein-cholesterol, and atherogenic indices in L-NAME group compared to the control and LR group (p < 0.05); NO and high density lipoprotein-cholesterol was significant lower in the L-NAME group compared to control and LR (p < 0.05). In conclusion, reduction in NO bioavailability alters lipid metabolism, which was rectified by ramipril.