AJP - Heart and Circulatory Physiology, Vol 239, Issue 5 651-H657, Copyright © 1980 by American Physiological Society
Effects of graded hypoxia on contraction of cultured chick embryo ventricular cells
W. H. Barry, J. Pober, J. D. Marsh, S. R. Frankel and T. W. Smith
The quantitative relationship between a given decrease in O2 tension (Po2)
and the degree of depression of contractile function is difficult to define
in intact myocardial tissues because of uncertainty in estimation of
diffusion limitations. We therefore have studied the effects of hypoxia on
contractility in a system with minimal series diffusion barriers,
consisting of single cells within spontaneously contracting monolayers
cultured from 10-day-old chick embryo ventricles. Reversible decreases in
amplitude and velocity of cell wall motion occurred over a 3- to 4-min
period when perfusate Po2 was less than 12 mmHg, and a maximum depression
to about 30% of control levels occurred at Po2 values less than 4 mmHg. On
reoxygenation, recovery of amplitude and velocity of contraction occurred
in less than 15 s. Inhibition of glycolysis with 0.1 mM iodoacetate
resulted in a more marked decrease in contraction amplitude and a
significant slowing of beating rate during hypoxia. In addition, the
critical Po2 at which contractile function became impaired was increased to
about 16 mmHg. Thus, high-energy phosphates derived from anaerobic
glycolysis appear to be able to support a reduced level of contractility
during brief periods of hypoxia in these cultured heart cells.
