Document Detail


Zinc uptake by proximal cells isolated from rabbit kidney: effects of cysteine and histidine.
MedLine Citation:
PMID:  1788054     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The aim of this study was to characterize the mechanisms of zinc transport in proximal cells isolated from rabbit kidney cortex. Uptakes of 65Zn were assessed under initial rate conditions, after 0.5 min of incubation. The kinetic parameters obtained at 20 degrees C were a Km of 15.0 +/- 1.5 microM, a Jmax of 208.0 +/- 8.4 pmol min-1 (mg protein)-1, and an unsaturable constant of 0.259 +/- 0.104 (n = 8). Cadmium competitively inhibited the zinc uptake, with a Ki value of 13.0 +/- 2.8 microM, while zinc competitively inhibited 109Cd uptake by isolated cells. Cysteine and histidine stimulated zinc transport at an amino acid:zinc molar ratio ranging from 1:1 to 8:1. This stimulation was not observed in the absence of a sodium gradient. At a molar ratio greater than 16:1 (i.e. 400 microM cysteine or histidine and 25 microM Zn), there was evidence of inhibition. These data suggest that zinc enters renal proximal cells (a) as a free ion via a saturable carrier-mediated process or an unsaturable pathway and (b) complexed with cysteine or histidine, by means of a sodium/amino acid cotransport mechanism.
Authors:
B Gachot; M Tauc; L Morat; P Poujeol
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Pflügers Archiv : European journal of physiology     Volume:  419     ISSN:  0031-6768     ISO Abbreviation:  Pflugers Arch.     Publication Date:  1991 Dec 
Date Detail:
Created Date:  1992-03-23     Completed Date:  1992-03-23     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0154720     Medline TA:  Pflugers Arch     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  583-7     Citation Subset:  IM    
Affiliation:
Département de Biologie cellulaire et moléculaire, CEN Saclay, Gif sur Yvette, France.
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MeSH Terms
Descriptor/Qualifier:
Animals
Biological Transport, Active / drug effects
Cadmium / metabolism,  pharmacology
Copper / pharmacology
Cysteine / pharmacology
Histidine / pharmacology
Kidney Tubules, Proximal / cytology,  drug effects,  metabolism*
Kinetics
Ligands
Male
Rabbits
Zinc / metabolism*
Chemical
Reg. No./Substance:
0/Ligands; 52-90-4/Cysteine; 71-00-1/Histidine; 7440-43-9/Cadmium; 7440-50-8/Copper; 7440-66-6/Zinc

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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