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KMID : 0390119940340010183
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Journal of Pusan Medical College
1994 Volume.34 No. 1 p.183 ~ p.194
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Calcium and Potassium Currents in Rabbit Basilar Artery Smooth Muscle Cells
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Abstract
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Membrane ionic currents were recorded in single smooth cells dissociated from rabbit basilar artery. When studied under voltage clamp with K+and 3 mM EGTA in the patch electrode, depolarization to potentials more positive than 0 mM from holding
potential of -60 mM, evoked outward current.
The outward current was reduced by tetraethylammonium (10 mM) and 4-aminopyridine (1 mM) applied to the external surface of the cells. Spontaneous transient outward current was revealed with 0.3 mM EGTA in patch electrode. And the calcium channel
locker, nifedipine, reduced outward current, suggesting that Ca2+-activated K+-current contributed to the outward current.
The voltage activated inward current was studied in isolation with Cs+ in recording electrode to block K+ current. In standard bathing solution containing 20 mM Ca2+, the inward current activated above -10 mM with peak inward current at +40 mM.
The
depolarization activated inward current was blocked by nifedipine and enhanced by BAY K 8644, providing evidence that it was Ca2+ current.
These results suggest the evidence that smooth cells from the rabbit basilar artery possess Ca2+-independent and dependent K+ channels and Ca2+ channel. Based on the voltage dependence of activation and inactivation and dihydropyridine
sensitivity,
L-type Ca2+ channels might predominate in rabbit basilar artery smooth muscles
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