Arachidonate incorporation and prostaglandin production in cultured endothelial and smooth muscle cells from pig aorta.

In order to investigate the utilization of arachidonic acid by vascular cells, we have compared cultured endothelial and smooth muscle cells from piglet aorta, after a 24 hour incubation with [ 3H ]-arachidonic acid [( 3H ] -AA). We studied both the release of labeled cyclo-oxygenase products, and the distribution of the radioactive fatty acid among lipids as determined by thin layer chromatography. As already described by others the main prostaglandins (PG) released by endothelial cells were PGF2 alpha and 6 keto-PGF1 alpha whereas smooth muscle cells mainly produced PGE2. These differences were associated with marked modification of the radioactivity distribution among the various lipid classes. In particular, the proportion of [ 3H ] -AA incorporated into neutral lipids was much more important in smooth muscle than in endothelial cells (approximately 40% of the total incorporated radioactivity versus 8%). On the other hand, the distribution of [ 3H ] -oleic acid into cell lipids after a 24 hour incorporation was very similar in both types of cells. These results suggest the existence of precise mechanisms controlling the incorporation and the availability of the PG precursor in the various types of cells. This might in part explain the differences observed for different cell types in the PG secretion pattern.