Prostaglandin and thromboxane synthesis by highly enriched rabbit proximal tubular cells in culture

Abstract

Prostaglandin synthetic profiles were studied in monolayers of highly enriched rabbit renal proximal tubular cells cultured in serum-free, hormone-supplemented, defined media. The cultures were initiated from glomeruli-free cortical suspensions. Cells in culture demonstrated morphologic and functional characteristics highly suggestive of proximal tubular cells. The basal and stimulated synthesis of immunoassayable prostaglandin (PG) E2, PGF2 alpha, 6-keto-PGF1 alpha, and thromboxane (Tx) B2 in response to various agonists, as well as the effect of two cyclooxygenase inhibitors, was assessed. Under both basal and stimulated conditions, PGE2 was the major product synthesized. PGF2 alpha and 6-keto-PGF1 alpha were synthesized to a lesser extent, and TxB2 was undetectable. The basal synthesis of PGE2 and PGF2 alpha in cultured cells was found to be higher than in isolated proximal tubular fragments by sevenfold and fivefold, respectively. Exogenous arachidonate, angiotensin II, and the divalent cation ionophore A23187 stimulated all three immunoassayable prostaglandins in a dose-dependent manner. Arginine vasopressin (10(-5) mol/L) had no stimulatory effect. In Ca++-free media or in the presence of 10(-5) mol/L Ca++ channel blocker, verapamil, the stimulatory effects of angiotensin II and A23187 were ameliorated. The stimulatory effect of angiotensin II was inhibited by saralasin (10(-5) mol/L), indicating that receptor binding could mediate PGE2 synthesis. Both indomethacin and sulindac sulfide (10(-5) mol/L) reversibly inhibited PGE2 synthesis.