Extracellular osmotic pressure modulates sodium-calcium exchange in isolated guinea-pig ventricular myocytes
1. The sensitivity of the cardiac Na(+)-Ca2+ exchange current to changes in osmotic pressure was investigated in guinea-pig ventricular myocytes, using the whole-cell patch-clamp technique. 2. A hyposmotic challenge applied by removal of sucrose from the standard bathing solution reduced exchanger c...
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Published in | The Journal of physiology Vol. 488; no. Pt 2; pp. 293 - 301 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
England
The Physiological Society
15.10.1995
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Subjects | |
Online Access | Get full text |
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Summary: | 1. The sensitivity of the cardiac Na(+)-Ca2+ exchange current to changes in osmotic pressure was investigated in guinea-pig
ventricular myocytes, using the whole-cell patch-clamp technique. 2. A hyposmotic challenge applied by removal of sucrose
from the standard bathing solution reduced exchanger current, measured as the Ni(2+)-sensitive component of whole-cell transsarcolemmal
current. These changes were fully reversible. 3. No response of whole-cell current to hyposmosis was observed when Ca2+ was
removed from the bathing solution by chelation with 1 mM EGTA. 4. Inclusion of 25 microM exchanger inhibitory peptide (XIP)
in the pipette solution caused a marked reduction in the Ni(2+)-sensitive component of membrane current, but the percentage
change in Ni(2+)-sensitive membrane slope conductance evoked by hyposmosis was the same as when XIP was omitted from the pipette
solution. 5. Exposure of cells to hyperosmotic solutions produced variable responses. In a majority of cells, solutions 30%
hyperosmotic compared with control evoked a persistent increase in exchanger current, whereas for solutions 50% hyperosmotic,
a larger but transient increase in current was observed. 6. Over a wide range of osmolalities (50-130% of isosmotic) the changes
in Ni(2+)-sensitive membrane slope conductance were linearly related to the changes in extracellular osmotic pressure. 7.
We propose that one consequence of exposing ventricular myocytes to anisosmotic solutions is modulation of Na(+)-Ca2+ exchange
current. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1113/jphysiol.1995.sp020967 |