The purpose of this study was to determine whether
digitalis glycosides alter the effect of
anoxia and reoxygenation on the cardiac myocytes and whether it could be modified by inhibition with
amiloride. Cardiac myocytes aggregates were prepared from ventricles of 7 day old chick embryos and were maintained in culture. They were exposed to a 2 hr
anoxia period followed by reoxygenation.
Anoxia produced a significant reduction in contractile frequency.
Ouabain, at low doses (10(-7) M and 10(-8) M), produced little effect in the absence of
anoxia but produced a marked and significant (p less than 0.05) reduction in contractile frequency in the presence of
anoxia. Myocytes exposed to
anoxia stopped beating only in the presence of 10(-7) M and 10(-6) M
ouabain and the time to cessation of spontaneous contraction was dependent on
ouabain dose.
Amiloride (10(-7) M or 10(-6) M) significantly (p less than 0.05) reduced but did not completely prevent the effect of
ouabain. During reoxygenation, beating rate returned to base line in control cells and those exposed to
ouabain (10(-8) M and 10(-7) M) but
ouabain slowed the rate of recovery. This slowing of recovery, produced by
ouabain, was prevented by
amiloride. These findings indicate the potentially deleterious effects of
digitalis glycosides in myocardial
anoxia and reoxygenation and the ability of
amiloride to oppose these adverse effects.