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KMID : 0377519950200040369
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Chung-Ang Journal of Medicine
1995 Volume.20 No. 4 p.369 ~ p.376
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Modulation of Ca-activated K Currents by Adrenergic Agonists in Vascular Smooth Muscle Cells of Rabbit
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Park Un-Sang
Lee Moo-Yeol
Bang Hyo-Weon
Uhm Dae-Yong
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Abstract
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Smooth muscle is widespread in all viscera and vessels, and presents diverse and different physiological characteristics according to its type(visceral or vascular, etc.), organ, and species. So many scientific attractions are focused on the smooth muscle to know its various physiological properties. In this study mesenteric arterial smooth muscle cell of rabbit was chosen to clarify the regulation mechanism of large conductance Ca-activated K current by adrenergic system. Whole-cell mode of patch clamp technique was used. The results from experimental studies were as follows : 1. In mesenteric arterial smooth muscle cell large oscillartory outward currents were recorded in depolarized state of membrance potential. 2. This outward current was reduced by depletion of intracellular calcium ion. 3. Alpha 1 and 2-adrenergic agonist(phenylephrine, clonidine) and antagonist(prazocin, yohimbin) did not affect these currents. 4. Beta adrenergic agonist(isoproterenol) markedly increased both amplitude and oscillartory characteristics of these currents. The effect of beta adrenergic agonist was almost antagonized by beta antagonist(propranolol). From these results it is suggested that large conductance Ca-activated K currents in mesenteric arterial smooth muscle cells are regulated by β-adrenergic agonist but not by α -adrenergic agonist.
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KEYWORD
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Ca-activated K current, arterial smooth muscle cell, β-adrenergic agonist
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