Passiflora quadrangularis L. PREVENTS EXPERIMENTAL HYPERTENSION AND VASCULAR REMODELLING IN RATS EXPOSED TO NITRIC OXIDE DEFICIT

BACKGROUND: Passiflora quadrangularis L. is among the species used in Colombian folk medicine for hypertension, but until now it has not been studied in experimental models. OBJECTIVES: To assess the capacity of P. quadrangularis EtOH extract to prevent the hypertension and vascular remodelling induced by nitric oxide (NO) deficit in Wistar rats. METHODS: The NO synthase inhibitor L-NAME (10 mg/kg, i.p, every 48h) was administered for seven weeks to the following groups of rats: P. quadrangularis 75, 150 and 300 mg/kg/d, p.o; enalapril as reference agent, 10 mg/kg/d, p.o. and vehicle as control (mixture of propylene glycol 10%, glycerine 10% and polysorbate 2%). Arterial blood pressure (BP) and heart rate (HR) were measured twice a week. After sacrifice, the aortic rings were isolated, contraction was triggered with phenylephrine (PE 10-6 M) and then the relaxant response achieved with cumulative concentrations of acetylcholine (ACh, 10-10 – 10-5 M) or sodium nitroprusside (SNP, 10-10 – 10-5 M) was assessed. Histopathologic measures of thickness/lumen ratio from both the left ventricle and aorta walls, as well as phytochemical screening, were also performed. RESULTS: As for enalapril, all doses of P. quadrangularis prevented the hypertension induced by L-NAME (less than 122.0±1.2 versus 154.8±1.3 mmHg at seventh week). P. quadrangularis significantly increased the relaxant effect induced by ACh in isolated aorta and decreased the thickness/lumen ratio of aorta wall specimens. CONCLUSION: P. quadrangularis L prevents experimental hypertension induced in rats with nitric oxide deficits improving the endothelium vasodilatation response and protecting against vascular remodelling.