Document Detail


Lactate transport in insulin-secreting beta-cells: contrast between rat islets and HIT-T15 insulinoma cells.
MedLine Citation:
PMID:  1324857     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The transport of L- and D-lactate into rat pancreatic islets and HIT-T15 insulinoma cells was studied by measuring uptake of 14C-labelled substrate at room temperature and by following changes in intracellular pH (pHi) in islets and HIT-T15 cells loaded with 2',7'-bis(carboxyethyl)-5'(6')-carboxyfluorescein (BCECF). Uptake of L-lactate into HIT-T15 cells was rapid, reaching equilibrium after 5 min with an apparent Km value of 4.8 mM. Transport was markedly inhibited by alpha-cyano-4-hydroxycinnamate, alpha-fluorocinnamate, quercetin and p-chloromercuribenzenesulphonate (pCMBS), and was enhanced in citrate medium. Uptake of D-lactate was less rapid, apparent equilibrium not being reached within 10 min. In contrast to HIT-T15 cells, rat pancreatic islets showed greatly reduced rates of transport of L- and D-lactate together with a correspondingly lower degree of inhibition by alpha-cyano-4-hydroxycinnamate. The addition of L- or D-lactate to HIT-T15 cells, but not dispersed islet cells, resulted in a marked and rapid intracellular acidification followed by a gradual recovery. In both HIT-T15 cells and isolated islets, the rates of transport of both L- and D-lactate in the presence of alpha-cyano-4-hydroxycinnamate were significantly greater in a depolarising K+ medium compared to the normal Na+ medium. These observations suggest that native rat islet cells have considerably reduced activity of the lactate-/H+ transport system compared to HIT-T15 insulinoma cells. There is evidence in both cell types of an additional electrogenic pathway for lactate which might play a role in coupling lactate efflux to beta-cell depolarisation.
Authors:
L Best; R Trebilcock; S Tomlinson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Molecular and cellular endocrinology     Volume:  86     ISSN:  0303-7207     ISO Abbreviation:  Mol. Cell. Endocrinol.     Publication Date:  1992 Jul 
Date Detail:
Created Date:  1992-09-29     Completed Date:  1992-09-29     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7500844     Medline TA:  Mol Cell Endocrinol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  49-56     Citation Subset:  IM    
Affiliation:
Department of Physiological Sciences, University of Manchester, Manchester Royal Infirmary, UK.
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MeSH Terms
Descriptor/Qualifier:
4-Chloromercuribenzenesulfonate / pharmacology
Amiloride / pharmacology
Animals
Biological Transport / drug effects
Carrier Proteins / antagonists & inhibitors,  metabolism*
Cells, Cultured
Coumaric Acids / pharmacology
Hydrogen-Ion Concentration
Insulin / secretion
Insulinoma / metabolism*,  pathology
Islets of Langerhans / metabolism*,  secretion
Lactates / pharmacokinetics*
Lactic Acid
Monocarboxylic Acid Transporters
Pancreatic Neoplasms / metabolism*,  pathology
Quercetin / pharmacology
Rats
Tumor Cells, Cultured / drug effects,  metabolism
Chemical
Reg. No./Substance:
0/Carrier Proteins; 0/Coumaric Acids; 0/Lactates; 0/Monocarboxylic Acid Transporters; 11061-68-0/Insulin; 117-39-5/Quercetin; 2609-46-3/Amiloride; 28166-41-8/alpha-cyano-4-hydroxycinnamate; 50-21-5/Lactic Acid; 554-77-8/4-Chloromercuribenzenesulfonate

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


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