Transport interactions of cystine and dibasic amino acids in isolated rat renal tubules.
Published
Journal Article
Isolated renal cortical tubules prepared from adult male Sprague-Dawley rats were used to study the nature of cystine entry into tubule cells and its transport interactions with dibastic amino acids. The uptake of cystine over time was progressive, reaching a steady-state after 60 min of incubation. Analysis of the intracellular pool after incubation revealed that a significant fraction of the transported cystine was reduced to cysteine. A kinetic analysis of uptake demonstrated that two systems for cellular entry of cystine existed with a Km1 of 0.012 mM and Km2 of 0.55 mM. Cystine uptake was sodium dependent with an apparent Km for sodium of 36 mEq/liter. Lysine inhibited cystine uptake via the low Km system, but appeared not to inhibit cystine uptake via the high Km system. Ornithine, leucine, and isoleucine each inhibited cystine uptake via the low Km system. Arginine appeared to affect both systems for cystine uptake. Cystine inhibited the uptake of lysine by isolated renal tubules. The data suggest that cystine at physiologic concentrations is transported into renal tubule cells nearly equally by two systems, of which, the low Km system is shared with the dibasic amino acids. A defective low Km system could in part explain human cystinuria.
Full Text
Duke Authors
Cited Authors
- Foreman, JW; Hwang, SM; Segal, S
Published Date
- January 1980
Published In
Volume / Issue
- 29 / 1
Start / End Page
- 53 - 61
PubMed ID
- 7351876
Pubmed Central ID
- 7351876
International Standard Serial Number (ISSN)
- 0026-0495
Digital Object Identifier (DOI)
- 10.1016/0026-0495(80)90098-0
Language
- eng
Conference Location
- United States