Abstract
Restriction of dietary sulfur results in reduced renal SO4 excretion, a finding attributed to decreased sulfur amino acid oxidation and filtered load of SO4. We found serum [SO4] in C57B1/6J adult male mice fed a “low-protein” (LP) diet (8% casein; 0.2% Met., 0.03% Cys) and in those fed a “high-protein” (HP) diet (27% casein; 0.68% Met., 0.1% Cys) for two weeks was not different (1.24±0.11 mM (x±SEM, n=6) vs 1.34±0.11 (n=7)). Reduced fractional SO4 excretion index (FEI SO4) was found in the LP group (LP=0.11±0.04 vs HP=0.50±0.14, p <.01). Evidence for adapted renal reabsorption was confirmed by assaying Na+-dependent uptake of 50 μM SO4 into renal brush border membrane vesicles (BBMV). Na+-dependent uptakes of 5 μM glucose and 50 μM phosphate served as internal markers; initial rates (15s) were normalized to those at equilibrium (60 min.). SO4 uptake was higher (361±39% of equilib. value n=10) in LP BBMV vs HP BBMV (270±16% n=10, p=0.023). No differences were noted with D-glucose (709±47% vs 698±30% n=5) or phosphate (193±17% vs 191±11%, n=11). The response to selective deficiency of dietary SO4 was studied using soybean-based diets with 1% NaCl (diet 1); 0.5% DL-methionine and 0.5% taurine (diet 2); and 1% Na2SO4 (diet 3). FEISO4 was 0.09± 0.01, 0.39±0.09, and 0.56±0.08, respectively. Adaptation was significant only with diet 1 (p <0.01). These findings indicate renal adaptation in BBM to depletion of SO4 per se.
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Cole, D., Scriver, C. 1490 ADAPTATION OF RENAL SULFATE (SO4) REABSORPTION TO SULFUR INTAKE. Pediatr Res 15 (Suppl 4), 691 (1981). https://doi.org/10.1203/00006450-198104001-01519
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DOI: https://doi.org/10.1203/00006450-198104001-01519