In vivo and in vitro studies on the mechanism of cardiovascular effects of Wu-Chu-Yu (Evodiae fructus).

The effects of the Chinese herb Wu-Chu-Yu (Evodiae fructus) on the cardiovascular function were assessed in anesthetized cats, conscious rats, and isolated preparations of rat aortic strip and auricle. In anesthetized cats, intravenous administration of alcohol-water crude extracts of Wu-Chu-Yu (0.03-0.24 g/kg) produced a dose-dependent hypertension and an increased contractile force of nictitating membrane which lasted for more than 5 min in higher doses. Phentolamine, but not tetraethylammonium antagonized hypertension and the increased contractile force of nictitating membrane induced by Wu-Chu-Yu. In conscious rats, hypertension was also observed by intraperitoneal administration of Wu-Chu-Yu (6 g/kg). Bilateral nephrectomy, administration of phentolamine or propranolol, all significantly decreased the hypertensive effect of Wu-Chu-Yu. Pretreatment with reserpine 24 hours in advance did not change the pressor effect of the crude extract. In aortic strip preparations, Wu-Chu-Yu caused the increase of contractile force, and the dose-response curve was parallel shift to the right in the presence of phentolamine. In auricle preparations, Wu-Chu-Yu produced positive inotropic and positive chronotropic effects, and the presence of propranolol changed the slope of Wu-Chu-Yu's dose-inotropic effect curve and reversed the chronotropic effect from positive to negative. Both in vivo and in vitro results suggested that alpha and beta adrenoceptors were directly involved in the cardiovascular effects of Wu-Chu-Yu.