The effect of papaverine on ion channels in rat basilar smooth muscle cells.
OBJECTIVE
Papaverine has been used in treating vasospasm following subarachnoid hemorrhage (SAH). However, its action mechanism for cerebral vascular relaxation is not clear. Potassium and calcium 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 examined the effect of papaverine on potassium and calcium 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 blocker, IBX (iberiotoxin) and a calcium chelator, BAPTA (1,2-bis(o-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid) in whole cell mode. Papaverine (100 microM) also inhibited L type Ca(2+) current recorded in isolated smooth muscle cells from rat basilar artery.


CONCLUSIONS
These results strongly suggest that Ca(2+)-activated potassium channels and L type Ca(2+) channels may be involved in papaverine-induced vascular relaxation in rat basilar artery.
Han
Dong Han
DH
Department of Neurosurgery, Research Institute of Clinical Medicine and Institute of Cardiovascular Research, Chonbuk National University School of Medicine, Jeonju, Chonbuk, Korea.
Bai
Guang Yi
GY
Yang
Tae Ki
TK
Sim
Byung Soo
BS
Kwak
Yong Geun
YG
Kim
Chul Jin
CJ
D000818:Animals; D001488:Basilar Artery / Q000166:cytology*; D002614:Chelating Agents / Q000494:pharmacology; D004307:Dose-Response Relationship, Radiation; D004347:Drug Interactions; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D007462:Iodobenzenes / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D032389:Myocytes, Smooth Muscle / Q000187:drug effects*; D010208:Papaverine / Q000494:pharmacology*; D018408:Patch-Clamp Techniques / Q000379:methods; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D002614:Chelating Agents; D007462:Iodobenzenes; D007473:Ion Channels; D010726:Phosphodiesterase Inhibitors; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; C476101:o-iodoxybenzoic acid; D004533:Egtazic Acid; D010208:Papaverine