[Hypotensive effect of dihydrolycorine]

Dihydrolycorine-HCL(DL) is a derivative of lycorine, an alkaloid isolated from Lycoris radiata Herb. DL iv 20, 40, and 80 mg.kg-1 lowered the mean arterial pressure in pentobar-bitone-anesthetized normotensive rats, cats, and conscious rats either normotensive or renovascular hypertensive. In pithed rats DL depressed the hypertensive effect of reaction to electric stimulation to the T7-9 segments of spinal cord. DL also depressed the hypertensive effect of phenylephrine. In rabbit aorta ring and rat anococcygeus muscle, DL antagonized the contractile effect of methoxamine, with pA2 values of 5.93 and 6.35, respectively. These results suggest that DL can block alpha 1-adrenoceptors.