6-Keto-prostaglandin E1-stimulated bone resorption in organ culture.

Previous investigations have shown that prostaglandin E2 (PGE2), 13, 14-dihydro-PGE2, and prostacyclin (PGI2) are among the most potent prostaglandin stimulators of bone resorption. 6-Keto-prostaglandin F1 alpha (6-keto-PGF 1 alpha; also called 6-oxo-prostaglandin F1 alpha), a metabolite of PGI2 formed by spontaneous hydrolysis, has little bone resorptive or other biological activity. The present study demonstrated that another metabolite of PGI2, 6-keto-prostaglandin E1 (6-keto-PGE1; also called 6-oxo-prostaglandin E1), was active in stimulating bone resorption in fetal rat long bone organ culture. 6-Keto-PGE1 stimulated significant release of previously incorporated 45Ca over the concentration range of 10(-9) to 10(-5) M. The potency of 6-keto-PGE1 was one-twelfth that of PGE2. If 6-keto-PGE1 is formed by bone or adjacent tissues, or reaches bone through the circulation, it could significantly affect bone mineral metabolism.