Hypotensive and diuretic activities of aqueous extract of Rauvolfia obscura K. Schum root bark in normotensive rats

Abstract

Rauvolfia obscura is a plant belonging to the Apocynaceae family, used in traditional medicine for its therapeutic virtues. Scientific information on the hypotensive and diuretic effects of the aqueous extract of R. obscura is very limited. The aim of this study was to evaluate the hypotensive and diuretic activities of the aqueous extract of R. obscura root barks in normotensive rats. The hypotensive effect of intravenous injection of the aqueous extract of R. obscura root bark at doses of 15 and 30 mg/kg was studied in normotensive rats. SAP and HR were measured by the invasive method. Diuretic activity was also assessed in rats. Cumulative excreted urine volumes over 6 h in rats were measured along with electrolyte analyses. Intravenous injection of R. obscura extract at doses of 15 and 30 mg/kg produced a dose-independent reduction in SAP (p<0.001). There was a significant reduction (p<0.001) in Fréquence Cardique. In addition, rats treated with R. obscura aqueous extract (150 and 300 mg/kg) and furosemide (40 mg/kg) had higher cumulative urine excreted volumes (EEV) over 6 h than control rats. These volumes were 53.08%, 114.14% and 166.72% respectively, compared with 50.6% in control rats. The results of electrolyte analyses (Na+, K+, Cl-) show that the extract increases natriuria, but decreases kaliuria. R. obscura aqueous extract has a powerful hypotensive effect in rats. It also has a weak diuretic effect in rats. It eliminates more sodium ions and spares potassium ions.