Arachidonic acid incorporation in cardiomyocytes, endothelial cells and fibroblast-like cells isolated from adult rat heart

Abstract

The incorporation of radiolabeled arachidonic acid (³[H]-AA) in normoxic cardiomyocytes (MC), cardiac endothelial cells (EC) and fibroblast-like cells (FL) isolated from adult rat heart was studied. Deposition of³[H]-AA in the cellular lipid pool was assessed with biochemical and autoradiographic techniques.

Extraction and subsequent analysis of lipids from the three different cell types revealed that MC contained significantly more triacylglycerols than EC and FL. The proportion of (unlabeled) AA was also higher in MC triacylglycerols than in EC and FL. The quantity of phospholipids did not differ among the three cell types studied. However, the content of (unlabeled) AA in the MC phospholipid pool was twice as high as in EC and FL.

The amount of³[H]-AA incorporated in the cellular lipid pool of MC, EC and FL depended on the concentration of AA in the incubation medium and the incubation time. In EC and FL incorporation of³[H]-AA was highest in the cellular phospholipid pool (0.01μM AA, 30 min incubation). With increased concentration of AA and longer incubation times, the cellular triacylglycerol pool became more important as site of³[H]-AA incorporation. In MC, comparable amounts of³[H]-AA were incorporated in the cellular triacylglycerol and phospholipid pools (0.01 and 1μM AA). At higher AA concentrations (10μM) the triacylglycerol pool was the preferred site of³[H]-AA deposition.

Autoradiograhic analysis at the light microscopic level revealed that the extra-nuclear space was readily stained when the three cell types were incubated with³[H]-AA. These findings indicate that all cellular lipid pools and membranes are most likely site of deposition of radiolabeled arachidonic acid. (Mol Cell Biochem116: 203–209,1992)