Faculty Collaboration Database

Metabolic studies of rat renal tubule cells loaded with cystine: the cystine dimethylester model of cystinosis. J Am Soc Nephrol 1995 Aug;6(2):269-72

Date

08/01/1995

Pubmed ID

7579095

DOI

10.1681/ASN.V62269

Scopus ID

2-s2.0-0029164566 (requires institutional sign-in at Scopus site)   38 Citations

Abstract

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.

Author List

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

Author

Ellis D. Avner MD Professor in the Pediatrics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adenosine Triphosphate
Animals
Cystine
Cystinosis
Kidney Tubules
Male
Mitochondria
Oxygen Consumption
Potassium
Rats
Rats, Sprague-Dawley
Sodium-Potassium-Exchanging ATPase