Comparison of prostaglandin biosynthetic activity between porcine aortic endothelial and smooth muscle cells in culture

Prostaglandin biosynthetic activity of miniature-pig aortic endothelial cells was compared with that of smooth muscle cells in culture. When used as homogenates, endothelial cells produced mainly PGE₂ and 6-ketoPGF(1α) (degradated product of PGI₂) from arachidonic acid, while they produced a large amount of PGF(2α) in addition to these when used as intact cells. Intact smooth muscle cells and their homogenates produced PGE₂ as a major product. 6-KetoPGF(1α) was produced by smooth muscle cells in the first few generations and became undetectable after several cultivations. 6-KetoPGF(1α) and PGE₂ were produced by intact or endothelium-depleted aortas. Our results suggest that both endothelial cells and smooth muscle cells in porcine aorta possess PGI₂ and PGE₂ biosynthetic activities. The subcultivation of smooth muscle cells, but not endothelial cells, in vitro resulted in the rapid disappearance of PGI₂ synthetase activity. The PGI₂ biosynthetic activity of endothelial cells was several fold higher than that of smooth muscle cells. Porcine smooth muscle cells' low ability to produce PGI₂ may offer a reason why atherosclerosis is easily developed in pigs.