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 Ca 2+, and on 4 5Ca 2+ retention in normal and in high K +-containing medium. Alismol affected neither the resting tension nor the 4 5Ca 2+ retention in normal medium, but it inhibited sustained contraction and increased 4 5Ca 2+ retention induced by high K + concentrations. Alismol did not affect norepinephrine-induced contractions in normal medium, nor phasic contractions in Ca 2+-free medium. These results suggested that alismol inhibited mainly Ca 2+ influx through a voltage-dependent Ca 2+ channel.