Time course of the effect of flunarizine on rabbit isolated vascular muscle

Flunarizine inhibited KCl contractions of the rabbit aorta, mesenteric artery and portal vein progressively over 3-4 h. The rate of development of block was approximately linear on a logarithmic scale and was similar for equieffective concentrations (aorta = 2.1 microM, mesenteric artery and portal vein = 0.21 microM). It is concluded that flunarizine can discriminate between calcium ion channels opened during the spike and those opened during sustained depolarization.