Increased production of prostacyclin (PGI2) by vascular intimal smooth muscle cells from atherosclerotic rabbit aorta

Abstract In vitro PGI 2 synthesis by aortic strips obtained from thoracic aorta of rabbits fed a high cholesterol diet was examined and compared with that of control rabbits fed a normal diet. In this report, the amounts of PGI 2 produced were shown as 6-keto-PGF 1α per μg of aortic tissue DNA instead of per mg wet weight. We also investigated PGI 2 synthesis by cultured smooth muscle cells (SMC) obtained from atherosclerotic intima. Basal PGI 2 production by aortic strips from atherosclerotic rabbit aorta was significantly augmented compared with that of controls. Arachidonic acid (AA)-induced PGI 2 production by atherosclerotic aorta was also significantly higher than that of controls. PGI 2 producing capacities of intimal and medial layers, separated from atherosclerotic aorta, were examined and the intimal layer was found to elicit a significantly greater PGI 2 production than the medial layer. Furthermore, cultured intimal SMC obtained from atherosclerotic rabbit aorta produced a greater amount of PGI 2 than medial SMC from normal rabbit aorta at various cultured conditions. These results suggest that the possibility of enhanced PGI 2 production by atherosclerotic aorta may well be considered as a defence mechanism of the vessel wall against damaging stimuli.