Calcium antagonism of anisodamine on isolated rabbit thoracic aorta

Anisodamine (Ani) or verapamil (Ver) relaxed the contracted thoracic aortic strips induced by CaCl2 and KCl in a noncompetitive manner with pD2' 3.6 and 5.8, respectively. Ani 50 mumol.L-1 and Ver 1 mumol.L-1 inhibited the intracellular Ca(2+)-dependent component of norepinephrine-induced contraction of aorta, but Ani 0.1 mmol.L-1 did not decrease the extracellular Ca(2+)-dependent component. In the presence of Ca2+, Ani 2.3 mumol.L-1 inhibited the proliferation of aortic smooth muscle cells. In the absence of Ca2+, the effect induced by Ani was biphasic-stimulatory at 2.3 mumol.L-1 concentrations and inhibitory at 61.7 mumol.L-1 concentrations. These results suggest that Ani, similar to Ver, mainly inhibits the potentially operated calcium channels.