Effects of alismol isolated from Alismatis Rhizoma on calcium-induced contraction in the rabbit thoracic aorta.

We examined the inhibitory effects of alismol, a sesquiterpenoid isolated from Alismatis Rhizoma, on vascular contractions induced by high concentrations of K+ and Ca2+, and on 45Ca2+ retention in normal and in high K+-containing medium. Alismol affected neither the resting tension nor the 45Ca2+ retention in normal medium, but it inhibited sustained contraction and increased 45Ca2+ retention induced by high K+ concentrations. Alismol did not affect norepinephrine-induced contractions in normal medium, nor phasic contractions in Ca2+-free medium. These results suggested that alismol inhibited mainly Ca2+ influx through a voltage-dependent Ca2+ channel.