Abstract
The renal transport and fractional reabsorption of inorganic sulfate is altered under conditions of sulfate deficiency or excess. The objective of this study was to examine the cellular mechanisms of adaptation of renal sodium/sulfate cotransport after varying dietary intakes of a sulfur containing amino acid, methionine. Female Lewis rats were divided into four groups and fed diets containing various concentrations of methionine (0, 0.3, 0.82 and 2.46%) for 8 days. Urinary excretion rates and renal clearance of sulfate were significantly decreased in the animals fed a 0% methionine diet or a 0.3% methionine diet, and significantly increased in the animals fed a 2.46% methionine diet when evaluated on days 4 and 7. Serum sulfate concentrations were unchanged by diet treatment in all animals. The fractional reabsorption of sulfate was significantly increased in the animals fed the 0% methionine diet and the 0.3% methionine diets, and decreased in the animals fed the 2.46% methionine diet. Increased mRNA and protein levels for the sodium/sulfate transporter (NaSi-1) were found in the kidney cortex following treatment with the 0 and 0.3% methionine diet groups. Sulfate homeostasis by renal reabsorption is maintained by an up-regulation of steady state levels of NaSi-1 mRNA and protein when the diet is low in methionine.
Footnotes
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Send reprint requests to: Dr. Marilyn E. Morris, 527 Hochstetter Hall, Department of Pharmaceutics, State University of New York at Buffalo, Amherst, NY 14260.
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↵1 This work was supported by NSF Grant IBN 9629470, a grant from the Western New York Kidney Foundation/Upstate NY Transplant Services, a multidisciplinary grant from the Research Foundation of State University of New York and a grant from the Kapoor Foundation of State University of New York at Buffalo (M.E.M.). Additional support was provided by National Institutes of Health Grant AG 10629 (R.R.A.) and Swiss National Science Foundation (H.M.).
- Abbreviations:
- BBM
- brush border membrane
- BLM
- basolateral membrane
- GFR
- glomerular filtration rate
- mRNA
- messenger RNA
- RT-PCR
- reverse transcriptase-polymerase chain reaction
- ELISA
- enzyme-linked immunosorbent assay
- DPH
- 1,6-diphenyl-1,3,5-hexatriene
- NaSi-1
- sodium/sulfate cotransport
- SSC
- standard saline citrate
- PBS
- phosphate-buffered saline
- Received April 8, 1998.
- Accepted July 5, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
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