Coronary Arterial Prostacyclin Synthetase and Prostaglandin E2 Isomerase Activities
Prostaglandin E2 (PGE2) isomerase and prostacyclin (PGI2) synthetase are the major endoperoxide (PGH2)-metabolizing enzymes present in microsomes isolated from vascular tissue. The PGE2 isomerase activity specifically requires the addition of GSH (Ogino et al., 1977). Prostacyclin has potent vasodilator and platelet antiag-gregatory activity (Vane, 1983). Therefore, modulation of PGI2 synthetase activity is of prime physiological importance in the regulation of blood vessel function. Reducing agents such as GSH have been reported to augment prostaglandin production by protecting the cyclooxygenase enzyme system (arachidonic acid→ PGH2) from self-catalyzed deactivation (Egan et al, 1976). However, little evidence exists for the effects of these agents on augmenting prostacyclin synthetase activity (McNamara et al.1984). We report the concentration-dependent modulation of the formation of 6-keto-PGF1α, the stable breakdown product of PGI2, by GSH and dithiothreitol (DTT) and unmasking of PGE2 isomerase in microsomes isolated from bovine coronary artery.
KeywordsMicrosomal Protein Isomerase Activity Prostaglandin Endoperoxide Human Saphenous Vein Incubation Volume
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