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KMID : 0377519950200030261
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Chung-Ang Journal of Medicine
1995 Volume.20 No. 3 p.261 ~ p.272
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Regulation of Ca-activated K channel by Okadaic Acid
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Uhm Dae-Yong
Koo Hyun-Nam
Lee Moo-Yeol
Bang Hyo-Weon
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Abstract
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High conductance Ca-activated K(maxi-K) channels were studied in inside-out patches with smooth muscle cells isolated from rabbit gastric antrum. These channels showed a single channel conductance of about 260 pS in symmetrical concentration of K (140mM) on both sides of the patch. The current-voltage relationship of the single channel was linear from +80 to -80mM of pipette voltage. When the cytoplasmic calcium concentration was changed from pCa 9 to 6, open probability of the channel started to increase and reached to a quasi-saturation. Mg and ATP respectively increased the channel activity in dose-dependent manner. Okadaic acid(100nM) increased the channel activity only in the presense of MgㆍATP. Therefore it could be concluded that maxi-K channel itself or an endogenous protein kinase activity which was firmly associated with the channel, was modulated by okadaic acid-sensitive phosphatase.
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KEYWORD
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Ca-activated K channel, Mg·ATP, okadaic acid, phosphatase
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