Metabolic studies of rat renal tubule cells loaded with cystine: the cystine dimethylester model of cystinosis.

Published

Journal Article

The cause of Fanconi syndrome in cystinosis is enigmatic. It has previously been shown that renal tubules could be loaded with cystine by incubating them with cystine dimethylester (CDE), mimicking the biochemical hallmark of cystinosis. Such tubules have impaired transport, decreased whole-cell O2 consumption, and substrate utilization. In this study, the metabolic disturbances in cystine-loaded renal tubule cells were further characterized. Isolated rat renal tubules were loaded with cystine by incubating them with 2 mM CDE for 10 min. This had no significant effect on total ATPase, Na(+)-K(+)-ATPase, or the ouabain-insensitive ATPase activity of renal tissue homogenates from these cystine-loaded tubules. Intracellular K was significantly lower in the cystine-loaded tubules (37 +/- 2 versus 47 +/- 3 nEq/mg; P < 0.008). Intracellular ATP was reduced by 39% in the cystine-loaded tubules (23.7 +/- 2.4 versus 38.1 +/- 3.3 nmol/mg of protein; P < 0.0025). CDE (2 mM) reduced isolated mitochondrial O2 consumption with glutamate as the substrate by 66% (4.7 +/- 0.7 versus 13.9 +/- 0.8 nm/min per mg of protein, P < 0.001) but had no effect on mitochondrial O2 consumption with succinate as the substrate. It was speculated that the impaired transport from cystine loading with CDE is secondary to a decrease in energy generation.

Full Text

Duke Authors

Cited Authors

  • Foreman, JW; Benson, LL; Wellons, M; Avner, ED; Sweeney, W; Nissim, I

Published Date

  • August 1995

Published In

Volume / Issue

  • 6 / 2

Start / End Page

  • 269 - 272

PubMed ID

  • 7579095

Pubmed Central ID

  • 7579095

International Standard Serial Number (ISSN)

  • 1046-6673

Language

  • eng

Conference Location

  • United States