Ca. Marra et Mjt. Dealaniz, ROLE OF CALCIUM IONOPHORE AND PHOSPHOLIPASE A(2) - INHIBITORS ON THE FATTY-ACID COMPOSITION OF HEPATOMA TISSUE-CULTURE CELLS AND LIPID SECRETION, Medical science research, 25(1), 1997, pp. 59-62
The effect of ionophore A-23187 (10 mu M) on the fatty acid compositio
n of polar and neutral lipids was studied in hepatoma tissue culture c
ells. As a consequence of a rise in calcium concentration, the monouns
aturated fatty acids palmitoleic and oleic increased, whereas polyunsa
turated fatty acids from the n-6 and n-3 series declined in cellular p
hospholipids after 10 min incubation. The ionophore also produced a de
crease in the relative content of oleic acid in neutral lipids. In the
secreted lipids, there was a significant rise in the percentage of ar
achidonic and eicosapentaenoic acids in the phospholipid fraction toge
ther with a decrease in oleic acid, caused by the incubation of cells
with the ionophore. A different effect was apparent in the fatty acid
composition of the secreted neutral lipids, with a decline in the rela
tive content of palmitic and stearic acids and a simultaneous increase
in oleic acid. All these effects were completely suppressed by pre-tr
eatment of the cells with the phospholiphase A(2) inhibitors quinacrin
e dihydrocloride (0.15 mM) and 4-bromophenacyl-bromide (0.05 mM). We c
onclude that phospholipase A(2) is involved in the calcium-mediated ch
anges in cell fatty acid composition and secretion.