Prostaglandin E2 inhibits oxygen consumption in rabbit medullary thick ascending limb

The effect of prostaglandin (PG) E2 on transport-dependent oxygen consumption (QO2) of rabbit medullary thick ascending limb (MTAL) cells was studied. Exogenous PGE2, at a concentration of 30 microM, inhibited ouabain-sensitive QO2 by 70%. Addition of either ouabain or bumetanide, after PGE2, further depressed QO2, whereas PGE2 had no effect when added after these transport inhibitors. There was no significant inhibition of QO2 by PGE2 in the absence of either Na or Cl. The QO2 of amphotericin-treated cells was inhibited by the addition of PGE2. Therefore the inhibitory effect of PGE2 was on the transport-dependent moiety of QO2 and was independent of Na entry. Other prostanoids had no significant effect on MTAL QO2. Suspensions of isolated MTAL cells accumulated PGE2 at about one-fifth the rate of outer medullary collecting duct cells. Finally, PGE2 caused an increase in intracellular adenosine 3',5'-cyclic monophosphate levels by approximately 100%. Although the precise mechanism of action is unclear, PGE2, which is synthesized by several cell types in the renal medulla, exerts an inhibitory effect on transport in rabbit MTAL.