AJP - Heart and Circulatory Physiology, Vol 271, Issue 5 1856-H1863, Copyright © 1996 by American Physiological Society
Action potentials in right and left ventricles from chronic hypoxic rats: effect of almitrine
P. Kreher, C. Keriel and X. Leverve
Laboratoire de Bioenergetique, Universite Joseph Fourier, Grenoble, France.
Rats were exposed to a 3-wk regimen of chronic normobaric hypoxia, with or
without almitrine treatment. Chronic hypoxia led to a significant rise in
the right ventricular mass and lengthened the action potential duration
(APD) in right ventricle and in nonhypertrophied left ventricle.
Hypertrophy and APD lengthening were significantly enhanced by almitrine.
The classical acute hypoxia-induced shortening in APD was much larger in
hypoxia-adapted hearts. In these hearts, almitrine treatment almost
completely prevented such shortening, while the acute hypoxia-induced
decrease in cardiac contraction was similar with or without almitrine. It
is concluded that APD lengthening during chronic hypoxia can occur
independently of ventricular hypertrophy. The similar directional effects
of almitrine and chronic hypoxia on APD support the hypothesis of an
energy-linked phenomenon. The dissociation of the almitrine effect on APD
and contractility is in accordance with the view of a cellular energy
compartmentation.
