The Effect of Papaverine on the Calcium-dependent K+ Current in Rat Basilar Smooth Muscle Cells

ABSTRACT

OBJECTIVE: Papaverine has been used in treating vasospasm following subarachnoid hemorrhage(SAH). However, its action mechanism for cerebral vascular relaxation is not clear. Potassium channels are closely related to the contraction and relaxation of cerebral smooth muscle. Therefore, to identify the role of potassium and calcium channels in papaverine-induced vascular relaxation, we examine the effect of papaverine on potassium channels in freshly isolated smooth muscle cells from rat basilar artery. METHODS: The isolation of rat basilar smooth muscle cells was performed by special techniques. The whole cell currents were recorded by whole cell patch clamp technique in freshly isolated smooth muscle cells from rat basilar artery. Papaverine was added to the bath solution. RESULTS: Papaverine of 100 microM into bath solution increased the amplitude of the outward K+ current which was completely blocked by BKCa(large conductance calcium dependent potassium channels)blocker, IBX(iberiotoxin), and calcium chealator, BAPTA(1, 2-bis(o-aminophenoxy)ethane-N, N, N', N'-tetraacetic acid), in whole cell mode. CONCLUSION: These results strongly suggest that potassium channels may play roles in papaverine-induced vascular relaxation in rat basilar artery.