Different effects of furosemide on urinary excretion of prostaglandin E2 and F2 alpha in rabbits.

The effect of a constant infusion of furosemide (130 micrograms/min i.v. for 60 min, n = 8) was studied on urinary excretion of water, electrolytes and immunoreactive prostaglandin E2 (iPGE2) and iPGF2alpha in chloralose-urethane anesthetized rabbits. During the furosemide infusion sodium and water excretion increased ten-fold and the excretion of potassium and iPGE2 two to three times. The excretion of iPGF2alpha (0.06 +/- 0.03 micrograms/min/100 g kidney weight) was not significantly changed during the furosemide infusion but increased markedly after the infusion and reached a maximum (1.0 +/- 0.6 microgram/min/100 g) 30 to 45 min later, while the small increase in iPGE2 excretion at this time could be attributed to cross-reaction with PGF2alpha. The results indicate that PGE2 might possibly be involved directly in the action of furosemide, while PGF2alpha might participate in sodium and water conserving mechanisms in the rabbit kidney, activated by the drug induced diuresis.