Unsaturated fatty acids mobilize intracellular calcium independent of IP3 generation and VIA insertion at the plasma membrane

Addition of oleic and arachidonic acids to Ehrlich ascites tumor cells mobilizes Ca2+ from the same intracellular pool as that mobilized by thapsigarin. Such mobilization occurs in the presence of the phospholipase C inhibitor U73122 as well as in cells treated with pertussis toxin. Co-addition of fatty acids and thapsigarin leads to initial rates of Ca2+ mobilization much greater than that induced by either compound alone. The responses induced by the fatty acids are observed also with other lipophiles like sphingosine, bromo-palmitate and the Ca2+ influx inhibitor econazole; all responses are rapidly reversed by addition of bovine serum albumin. Many of the above effects of fatty acids are observed also in Jurkat T lymphocytes and Friend erythroleukemia cells. The experiments provide evidence of lipid-induced plasma membrane perturbations that influence intracellular Ca2+ mobilization independent of the generation of currently known second messengers.