Prostaglandin F2 alpha inhibits acidification in H(+)-secreting epithelia

The role of prostaglandins in the regulation of acidification mechanisms in H(+)-secreting epithelia has been investigated in the abdominal skin of the southern leopard frog, Rana pipiens. Exogenous administration of prostaglandin (PG) E2 and PGF1 alpha (10(-7) M) to the serosal media of paired skins mounted in modified Ussing chambers showed no significant alteration on H+ excretion rates. PGF2 alpha exhibited a dose-dependent inhibition of acidification in both the mucosal and serosal media of animals in normal acid-base states. The ED50 was determined to be 5 X 10(-8) M. Animals placed in an NH4Cl-induced chronic metabolic acidosis demonstrated enhanced H+ excretion from normal which was inhibited by PGF2 alpha (10(-8) M). Frogs treated with ibuprofen (30 mg/kg/day for 3 days) stimulated mucosal acidification to a magnitude similar to the chronic metabolic acidosis animal, and this was inhibited by PGF2 alpha (10(-8) M) during the recovery phase. PGF2 alpha produced effects on both the mucosal proton excretion system and the serosal Na+/H+ exchanger mechanism. PGF2 alpha appears to function in this H(+)-secreting epithelia to maintain a low basal H+ excretion rate and to regulate intracellular pH.