Blood-Pressure Lowering, Positive Chronotropy and Inotropy by theVeratrumAlkaloids Germidine and Germerine but Negative Chronotropy by Veratridine in Mice

摘要

Germidine and germerine, theVeratrumalkaloids lowered blood pressure accompanied with positive chronotropy and inotropy in mice. Germerine was more potent than germidine in both blood-pressure lowering and positive inotropy, whereas veratridine produced negative chronotropy and positive inotropy. An acyl group (an acetyl or a 2-methylbutyroyl group) at 3-O-R1position and a 2-methylbutyroyl group at 15-O-R2position in germine were important to produce the positive inotropy and chronotropy. The presence of a veratroyl group at 3-O-R1position and a free hydroxyl group at 15-O-R2position may be essential to produce the negative chronotropy by veratridine. The positive inotropy by germidine and veratridine may be due to TTX-resistant Na+channel activation.