ANTIHYPERTENSIVE ACTIVITY OF DL-TETRAHYDROPALMATINE, AN ACTIVE ALKALOID ISOLATED FROM THE TUBERS OF CORYDALIS-RACEMOSA

The antihypertensive activity of dl-tetrahydropalmatine hydrochloride (THP), isolated from the tubers of Corydalis racemosa (Thunb.) Pers. ( Papaveraceae), was investigated in spontaneously hypertensive rats (SH Rs) using intravenous injection. A dose-dependent lowering of blood pr essure was observed in SHRs. Decrease of plasma noradrenaline was also obtained in SHRs that received injection of THP. Direct injection of THP into brain lowered the blood pressure and plasma noradrenaline. Th is antihypertensive action of THP appears to be produced mainly by an effect on central nervous system to lower sympathetic tone in SHRs.