Vasorelaxant effect of Hyptis fruticosa dichloromethane extract (HFDE) on isolated rings of rat mesenteric artery was evaluated in this study. In intact rings, HFDE (0.1-3000 µg/mL) induced concentration-dependent vasorelaxations (Emax = 119±14%; n = 6) of phenylephrine tonus that were not modified after endothelium removal (Emax = 116±6%; n = 6), after KCl 20 mM (Emax = 135±9%; n = 6) or in rings pre-contracted with KCl 80 mM (Emax = 125±4%; n = 6). In endothelium denuded rings, HFDE (300 or 1000 µg/mL) inhibited contractions induced by CaCl2 (maximal inhibition = 25±7% and 95±1%; respectively). Furthermore, HFDE promoted an additional vasorelaxation (15±3%; n = 7) after maximal response of 10 µM nifedipine (78±3%; n = 7). In conclusion, HFDE induces vasorelaxant effect through an endothelium-independent pathway, which appears to be due in major part to inhibition of the Ca2+ influx through voltage-operated Ca2+ channels.
Hyptis fruticosa; dichloromethane extract; vasorelaxant effect; mesenteric artery; rats
