Ca2+ translocation across liposomal membranes enhanced by unsaturated long-chain fatty acids.
The putative ionophoretic action of phosphatidic acid or arachidonic acid metabolites for Ca2+ has offered an attractive explanation for stimulation-coupled mobilization of cytoplasmic Ca2+. We have examined the effects of Ca2+ ionophore and long-chain unsaturated fatty acids on the translocation of Ca2+ across the liposomal membrane by using Quin II-entrapped liposomes, a sensitive assay system for ionophoresis of Ca2+. A23187 increased Quin II fluorescence intensity corresponding to the translocation of Ca2+ into liposomes. Similar translocation was observed with unsaturated long-chain fatty acids but not with saturated fatty acids. Thus, when phospholipases of cell membrane are activated by certain stimuli, unsaturated long-chain fatty acids are liberated and might mediate the mobilization of cytoplasmic Ca2+.
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Utsumi
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Nobori
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Miyahara
D001095:Arachidonic Acids / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D008041:Linoleic Acids / Q000494:pharmacology; D008081:Liposomes / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
D001095:Arachidonic Acids; D005231:Fatty Acids, Unsaturated; D007473:Ion Channels; D008041:Linoleic Acids; D008081:Liposomes; D000001:Calcimycin; D002118:Calcium