Document Detail


Membrane potential and amino acid transport in a mutant Chinese hamster ovary cell line.
MedLine Citation:
PMID:  2022695     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The bioenergetics of amino acid transport system A was studied in two Chinese hamster ovary (CHO) cell lines, the parent line CHO-PEOT/1 and CHY-1, a mutant of the former exhibiting a low activity of the same transport system. The steady-state transmembrane distribution ratio of the cationic amino acid L-arginine (RARG) was employed as an indicator of membrane potential (delta psi). Evidence for the reliability of RARG to measure delta psi can be summarized as follows: (1) L-arginine transmembrane distribution increased under conditions of cell hyperpolarization and decreased under conditions of cell depolarization; (2) L-arginine distribution conformed closely to that expected for a probe of delta psi in conditions in which delta psi depends largely on the transmembrane potassium gradient; and (3) the value of delta psi obtained through a valinomycin null point experiment (-72.7 mV) was very similar to the value calculated from L-arginine distribution using the Nernst equation (-73.4 mV). The transmembrane gradient of sodium electrochemical potential (delta mu Na), the driving force for the operation of system A, was slightly higher in the mutant cell line CHY-1. In the same line, the intracellular level of the specific system A substrate MeAIB at steady state was also higher. Studies of the rheogenicity of system A in the two lines indicated that the depolarization associated with the entry of substrates of system A was proportional to the amount of amino acid taken up by the cells. Kinetic analysis showed that the low activity of system A in the mutant cell line was referrable to a decrease in transport Vmax. It is concluded that neither a decrease in energy available for the operation of system A nor a decreased efficiency of coupling of the system to delta psi is responsible for the defect observed in the mutant line.
Authors:
B M Rotoli; O Bussolati; V Dall'Asta; G C Gazzola
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of cellular physiology     Volume:  146     ISSN:  0021-9541     ISO Abbreviation:  J. Cell. Physiol.     Publication Date:  1991 Mar 
Date Detail:
Created Date:  1991-06-05     Completed Date:  1991-06-05     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0050222     Medline TA:  J Cell Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  417-24     Citation Subset:  IM    
Affiliation:
Istituto di Patologia Generale, Università di Parma, Italy.
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MeSH Terms
Descriptor/Qualifier:
Alanine / metabolism
Amino Acids / pharmacokinetics*,  pharmacology
Animals
Arginine / diagnostic use,  metabolism
Biological Transport / drug effects,  physiology
Cell Line
Cricetinae
Cricetulus
Electric Conductivity / drug effects,  physiology
Female
Membrane Potentials / drug effects,  physiology*
Ovary / cytology*,  metabolism,  physiology
Proline / metabolism,  pharmacology
Sodium / pharmacology
Chemical
Reg. No./Substance:
0/Amino Acids; 147-85-3/Proline; 56-41-7/Alanine; 74-79-3/Arginine; 7440-23-5/Sodium

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


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