Prostaglandin D2 formation and characterization of its synthetases in various tissues of adult rats.

When the amounts of primary prostaglandins formed from endogenous arachidonic acid were determined in homogenates of various tissues of adult rats, prostaglandin D2 was the major prostaglandin found in most tissues. It was formed actively in the spleen (3100 ng/g tissue/5 min at 25 degrees C), intestine (2600), bone marrow (2400), lung (1100), and stomach (630); moderately in the epididymis, skin, thymus, and brain (140-340); and weakly in other tissues (less than 100). Addition of exogenous arachidonic acid (1 mM) accelerated the formation of prostaglandin D2 in all tissues as follows: spleen (15,000); bone marrow, intestine, thymus, liver, and lung (1600-5200); stomach, adrenal gland, epididymis, brain, salivary gland, skin, spinal cord, and seminal vesicle (380-1000); and other tissues (80-310). The activity of prostaglandin D synthetase (prostaglandin-H2 D-isomerase) was detected in 100,000g supernatants of almost all tissues. As judged by glutathione requirement for the reaction, inhibition of the activity by 1-chloro-2,4-dinitrobenzene, and immunotitration or immunoabsorption analyses with specific antibodies, the enzyme in the epididymis, brain, and spinal cord (1.8-9.2 nmol/min/mg protein) was glutathione-independent prostaglandin D synthetase (Y. Urade, N. Fujimoto, and O. Hayaishi (1985) J. Biol. Chem. 260, 12410-12415). The enzyme in the spleen, thymus, bone marrow, intestine, skin, and stomach (2.0-57.1) was glutathione-requiring prostaglandin D synthetase (Y. Urade, N. Fujimoto, M. Ujihara, and O. Hayaishi (1987) J. Biol. Chem. 262, 3820-3825). The activity in the kidney and testis (3.7-4.5) was catalyzed by glutathione S-transferase. The activity in the liver, lung, adrenal gland, salivary gland, heart, pancreas, and muscle (0.6-5.1) was due to both the glutathione-requiring synthetase and the transferase.