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ACTION POTENTIAL MODIFICATIONS IN RAT MYOCARDIAL CELLS INDUCED BY HYPERVITAMINOSIS A
Author(s) -
Ventura U.,
Ceriani T.,
Zelaschi F.,
Rindi G.
Publication year - 1971
Publication title -
quarterly journal of experimental physiology and cognate medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0033-5541
DOI - 10.1113/expphysiol.1971.sp002113
Subject(s) - depolarization , repolarization , intracellular , chemistry , biophysics , medicine , membrane , membrane potential , ventricular action potential , heart cells , endocrinology , membrane permeability , cell , electrophysiology , biology , biochemistry , myocyte
Ventricular cell action potentials were measured in situ using intracellular microelectrodes in the hearts of hypervitaminotic A rats, both at the spontaneous rate and at rates externally increased to various higher levels. The action potentials were much modified (decrease in amplitude, in depolarization rate, in fast and slow repolarization rate, and increase in partial and total duration). Excess of vitamin A also appeared to bring about a rise in spontaneous heart rate. Ion fluxes in myocardial cells at high levels of vitamin A seemed to be somewhat uncoupled from cardiac metabolism. The results obtained indicate that the changes in cardiac electrogenesis may be specifically related to the effects of an excess of vitamin A on cell membrane structure and consequently on permeability and ion fluxes through the membranes.