Renal serine production in vivo: effects of dietary manipulation of serine status.

Renal serine production in rats was quantitated by simultaneously measuring renal blood flow and the renal arteriovenous difference for this amino acid. The rate of synthesis was 0.24 +/- 0.02 mumol.min-1.100 g-1 in rats fed a diet containing 12% casein. This rate was not altered by the inclusion of an additional 1% serine in the diet for 7 days or by acute infusion of serine, although both protocols increased blood serine by 50%. When rats were fed a diet in which protein was entirely replaced by crystalline amino acids the rate of renal serine production was also 0.25 +/- 0.05 mumol.min-1.100g-1. Omission of serine or both serine and glycine from this diet did not alter the rate of renal serine synthesis. Renal serine production does not respond to the serine content of the diet.