The effect of prostaglandin inhibition on renal function in the developing anesthetized lamb

The importance of prostaglandin (PG) compounds for renal function in the developing kidney was studied by comparing renal blood flow (RBF), glomerular filtration rate (GFR) and fractional sodium (Na) excretion in control lambs and lambs treated with a PG synthesis inhibitor, indomethacin. The lambs were 1-2 and 4-6 weeks old and they were studied either during hydropenia (HP) or volume expansion (VE). Indomethacin significantly decreased Na excretion in both groups of hydropenic lambs. Indomethacin also completely blunted the natriuretic response to VE in the older lambs but had no effect on Na excretion in the volume expanded younger lambs. It is concluded that partial lack of PG inhibiting action on tubular Na transport will contribute to the poor natriuretic response to VE in neonatal lambs. Since PG will act locally rather than being blood-borne messengers, The divergent PG action in younger and older lambs might be explained by local differences in maturation of PG metabolism as well as by local differences in the maturation of PG sensitivity.