Effects of imipramine on isolated rabbit basilar artery

Imipramine (Imi) inhibited the contractile response to BAY k 8644 (IC50 = 2.39 +/- 0.33 mumol.L-1), KCl (IC50 = 1.00 +/- 0.09 mumol.L-1), in rabbit basilar artery rings. Imi was more effective in suppressing the contractile response evoked by KCl, CaCl2, and 5-HT in basilar artery rings than in mesenteric artery rings. The effect of Imi was the same as that of diltiazem (Dil). There was no difference between the inhibitory response of Imi on contraction induced by KCl in basilar artery rings with or without endothelium. The results suggest that Imi may block the calcium channel and inhibit the rabbit basilar artery selectively, and the effect is endothelium-independent.