Effect of diet on renal response to salt challenge in neonatal piglets.

In piglets 14-40 days of age, blood pressure and glomerular filtration rate increased significantly with age and were lower than those reported for adult pigs. There was no effect of dietary salt on the maturation of these parameters and on tubular sodium reabsorption, although the piglets on a low salt diet had lower inulin space than piglets receiving higher dietary salt. After the completion of a 24-hour salt challenge there was little evidence of sodium retention and there was no effect of previous dietary salt intake on sodium excretion. However, salt challenge resulted in higher blood pressure and elevated serum sodium only in piglets on a low sodium diet. These results suggest that in contrast to puppies and infants, the renal response to salt challenge is physiologically adequate in piglets at 14-40 days although glomerular function is still immature. Dietary salt history appears to have little effect on the degree of sodium excretion during salt challenge in this age range.