Synthesis of prostaglandin 6-keto F1α by cultured aortic smooth muscle cells and stimulation of its formation in a coupled system with platelet lysates

Lysed aortic smooth muscle cells, when incubated with ¹⁴C] araachidonate, synthesized only one radioactive product, which was identified as 6-keto-PGF. Formation of this product from smooth muscle cell lysates was stimulated when human platelet extracts were added to the system, and further stimulation was observed when imidazole, as selective inhibitor of thromboxane synthesis, was added to this coupled system. These observations indicate that the cyclooxygenase of the smooth muscle cells was rate-limiting, that the prostacyclin synthetase of these cells can utilize endoperoxides produced by platelets, and that blocking of thromboxane synthesis might, under certain conditions, shunt arachionate metabolism toward prostacyclin formation.