UNSATURATED FATTY-ACIDS MOBILIZE INTRACELLULAR CALCIUM-INDEPENDENT OFIP3 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 thapsigargin. Such mobilization occurs in the presence of the phosphol ipase C inhibitor U73122 as well as in cells treated with pertussis to xin. Co-addition of fatty acids and thapsigargin leads to initial rate s of Ca2+ mobilization much greater than that induced by either compou nd alone. The responses induced by the fatty acids are observed also w ith other lipophiles like sphingosine, bromo-palmitate and the Ca2+ in flux inhibitor econazole; all responses are rapidly reversed by additi on of bovine serum albumin. Many of the above effects of fatty acids a re observed also in Jurkat T lymphocytes and Friend erythroleukemia ce lls. The experiments provide evidence of lipid-induced plasma membrane perturbations that influence intracellular Ca2+ mobilization independ ent of the generation of currently known second messengers. (C) 1997 A cademic Press.