Membrane fluidity and kinetics of Ca2+-dependent potassium channels.
Patch-clamp technique and fluorescence polarization analysis were used to study the effect of lipids on the kinetic of Ca2+-dependent K+ channels and membrane fluidity. Cultured smooth muscle cells from human and rabbit aortas were used. 2-decenoic acid (DA) was applied to increase membrane fluidity and cholesterol (CHS) level was varied using mevinolin (MEV) and CHS-enriching medium. In the presence of 0.5 microM Ca2+ and 2 mM Mg2+ more than 40-fold elevation in the probability of the channels been open (Po) was observed under DA action. Treatment of cells with MEV leads to nearly 2 fold increase in membrane fluidity and to more than 4 times elevation of Po. The addition of CHS to the cell membrane resulted in a nearly 2 fold decrease in membrane fluidity and about 2 fold decrease in Po. The data suggest that lipid content affect the kinetics of Ca2+-activated K+ channels presumably due to changes in membrane fluidity.
Institute of Experimental Cardiology, Cardiology Research Center, USSR Academy of Sciences, Moscow.
P D
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Bregestovski
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Bolotina
D000818:Animals; D002118:Calcium / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D002784:Cholesterol / Q000494:pharmacology; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008148:Lovastatin / Q000494:pharmacology; D008560:Membrane Fluidity; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism*; D011817:Rabbits
D005229:Fatty Acids, Monounsaturated; D015221:Potassium Channels; C052476:2-decenoic acid; D002784:Cholesterol; D008148:Lovastatin; D011188:Potassium; D002118:Calcium