Abstract
Effects of alismol, a sesquiterpenoid isolated from the rhyzome of Alisma orientale, on adrenergic mechanisms were examined in the isolated rabbit ear artery. Alismol (10-6 to 10-4- M) inhibited the contraction of isolated rabbit ear artery by electrical stimulation of the perivascular nerves. The inhibition was concentrationdependent; at a concentration of 10-4 M, the inhibition was 90% (n=8). Treatment with 10-4 M alismol inhibited the increase in 3H-noradrenaline (3H-NAd) release induced by electrical stimulation by 63±6%. Alismol at 10-4 M did not affect the neuronal uptake of 3H-NAd in the artery. Alismol at 10-4 M slightly inhibited contractions induced by exogenously administered NAd. These results demonstrate that alismol inhibits the adrenergic neuro-effector mechanisms in rabbit ear artery, and they suggest that alismol acts primarily on nerve terminals and inhibits their responses to electrical stimulation by interfering with NAd release.
