Document Detail


Regulation of intracellular pH in cardiac muscle during cell shrinkage and swelling in anisosmolar solutions.
MedLine Citation:
PMID:  8141367     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effect on intracellular pH (pHi) of exposure to solutions of progressively increasing osmolarity from 418 to 620 mosM and to hyposmolar solutions (240 mosM) was examined in guinea pig ventricular muscle using ion-selective microelectrodes. Exposure of tissue to 418 mosM Tyrode solution (100 mM sucrose added) produced an intracellular alkalosis of approximately 0.1 U, whereas exposure to 620 mosM solution (300 mM sucrose added) caused an intracellular acidosis of approximately 0.1 U. The maximal rate of recovery of pHi from acidosis induced by an NH4Cl prepulse increased progressively as extracellular osmolarity was raised from 310 to 620 mosM. This suggests that the acidosis observed at steady state in 620 mosM solution is not due to inhibition of the Na(+)-H+ exchanger. In the presence of 10 microM ryanodine, exposure to 620 mosM solution produced a sustained intracellular alkalosis. We suggest that the decrease in pHi during exposure to 620 mosM solution is due, at least in part, to the acidifying influence of Ca2+ release from the sarcoplasmic reticulum. This decrease in pHi is expected to contribute to the negative inotrop reported in studies of cardiac contractility in markedly hyperosmolar solutions. There was no change in pHi when tissue was exposed to hyposmolar solution. However, the maximal rate of recovery of pHi from acidosis was slower in hyposmolar than in isosmolar solution, despite a concomitant decrease in the intracellular buffer capacity. This suggests that osmotic cell swelling results in inhibition of the sarcolemmal Na(+)-H+ exchanger.
Authors:
D W Whalley; P D Hemsworth; H H Rasmussen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  266     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1994 Feb 
Date Detail:
Created Date:  1994-04-26     Completed Date:  1994-04-26     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H658-69     Citation Subset:  IM    
Affiliation:
Department of Cardiology, Royal North Shore Hospital, St. Leonards, Sydney, Australia.
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MeSH Terms
Descriptor/Qualifier:
Amiloride / analogs & derivatives,  pharmacology
Animals
Cells, Cultured
Electric Stimulation
Female
Guinea Pigs
Heart / drug effects,  physiology*
Hydrogen-Ion Concentration*
Hypertonic Solutions
Male
Membrane Potentials / drug effects,  physiology
Microelectrodes
Myocardium / cytology,  metabolism*
Osmolar Concentration
Chemical
Reg. No./Substance:
0/Hypertonic Solutions; 1214-79-5/5-dimethylamiloride; 2609-46-3/Amiloride

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


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