Influence of prostaglandins on sodium transport of isolated medullary nephron segments.

The possibility that prostaglandins (PG) located in the renal medulla may influence renal excretion of sodium by a direct tubular action was examined by the addition of prostaglandins PGE2, PGF2alpha, and PGA2 to the peritubular and luminal surfaces of isolated perfused medullary thick ascending lumbs and collecting tubules from rabbit kidneys. The prostaglandins at both high (2.5 x 10(-4) M) and low (10 (-10) M, 10 (-7) M) concentrations had no effect on transepithelial potential difference and net sodium flux across these segments. Pretreatment of the animals with indomethacin did not influence the results. In vivo, both PGE2 and PGF2alpha, caused a natriuresis when infused directly into one renal artery, whereas PGA2 had no effect on sodium excretion. The prostaglandin inhibitors indomethacin, meclofenamate, and RO 20-5720 similarly had no direct effect on sodium transport in the nephron segments studied. It is concluded that the previously observed influence of prostaglandins and prostaglandin inhibitors on renal excretion of sodium in vivo are not mediated by a direct tubular action.