Both membrane stretch and fatty acids directly activate large conductance Ca(2+)-activated K+ channels in vascular smooth muscle cells
Biochemistry & Molecular Pharmacology
Graduate School of Biomedical Sciences; Department of Physiology
Medical Subject Headings
Animals; Arachidonic Acid; Calcium; Cations; Cell Membrane; Fatty Acids; Membrane Potentials; Muscle, Smooth, Vascular; Myristic Acid; Myristic Acids; Potassium Channels; Pulmonary Artery; Rabbits
Life Sciences | Medicine and Health Sciences
Large conductance Ca(2+)-activated K+ channels in rabbit pulmonary artery smooth muscle cells are activated by membrane stretch and by arachidonic acid and other fatty acids. Activation by stretch appears to occur by a direct effect of stretch on the channel itself or a closely associated component. In excised inside-out patches stretch activation was seen under conditions which precluded possible mechanisms involving cytosolic factors, release of Ca2+ from intracellular stores, or stretch induced transmembrane flux of Ca2+ or other ions potentially capable of activating the channel. Fatty acids also directly activate this channel. Like stretch activation, fatty acid activation occurs in excised inside-out patches in the absence of cytosolic constituents. Moreover, the channel is activated by fatty acids which, unlike arachidonic acid, are not substrates for the cyclo-oxygenase or lypoxygenase pathways, indicating that oxygenated metabolites do not mediate the response. Thus, four distinct types of stimuli (cytosolic Ca2+, membrane potential, membrane stretch, and fatty acids) can directly affect the activity of this channel.
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Citation: FEBS Lett. 1992 Feb 3;297(1-2):24-8.
Kirber, Michael T.; Ordway, Richard W.; Clapp, Lucie H.; Walsh, John V.; and Singer, Joshua J., "Both membrane stretch and fatty acids directly activate large conductance Ca(2+)-activated K+ channels in vascular smooth muscle cells" (1992). GSBS Student Publications. 607.