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KMID : 0377519940190030315
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Chung-Ang Journal of Medicine
1994 Volume.19 No. 3 p.315 ~ p.328
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Effects of Divalent Cations on Calcium-activated Potassium Currents of Smooth Muscle Cells
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Abstract
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Potassium channels participate in controlling mechanism of membrane excitability and contractile activity in gastric antral smooth muscle. Especially, the large conductance Ca2+-activated K+ channel is more important and abundant in many types of
smooth
muscle cells. From these studies gastric antral smooth muscle cells were used to clarify the effects of divalent cations on Ca2+-activated K+ channel. Mg2+ and Ba2+were used because many physiological roles were studied with them. Inside-out mode
of
patch clamp techique was used. Ca2+-activated K+ channels were found and they showed typical characteristics of the channel such as voltage and Ca2+ dependency.
Mg2+ increased the channel activity dose dependently. And the effects were saturated about 2mM. However Mg2+ decreased the single channel current dose dependently.
Ba2+ affacted the channel activity more complex than Mg2+, It increased the channel activity at lower Ba2+ and Ca2+ concentrations, but decreased at higher Ca2+ and Ba2+ concentrations. Membrane potential also affected the effects of Ba2+. As the
increase of Ba2+ concentration beginning point of Ba2+ effects shifted the to left of membrane potential axis.
From the results it could be suggested that Mg2+ and Ba2+ can modulate the activity of Ca2+-activated K2+ channel in gastric antral smooth muscle.
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KEYWORD
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