AJP - Cell Physiology, Vol 245, Issue 5 316-C321, Copyright © 1983 by American Physiological Society
Calcium elevation in cultured heart cells: its role in cell injury
E. Murphy, J. F. Aiton, C. R. Horres and M. Lieberman
Inhibition of the Na+-K+ pump in cultured embryonic chick heart cells
promotes the elevation of intracellular Ca2+ and is a useful manipulation
to study the relationship between Ca2+ and myocardial cell injury. One hour
of Na+-K+ pump inhibition resulted in a fourfold increase in cell Na+, a
50% decline in cell K+, and a 5- to 10-fold increase in cell Ca2+, 45% of
which is mitochondrial. The degree of cell injury induced by Ca2+ loading
was evaluated by monitoring the content of adenosine 5'-triphosphate (ATP)
and the release of the intracellular enzyme lactate dehydrogenase (LDH).
Under these conditions ATP content declined by 25-30% and LDH release
increased from 1 to 1.4% of the total LDH. Furthermore, cells subjected to
1 h of Na+-K+ pump inhibition and returned to control solution for 5 h
showed that Ca2+ decreased to near control levels and ATP content was
restored. Although inhibition of Na+-K+ transport caused a large increase
in cell Ca2+, neither Na+-K+ pump inhibition nor elevation in total cell
Ca2+ per se resulted in irreversible myocardial cell injury.
