Increased propensity of the aged myocardium to develop calcium-related electrophysiological alterations.
The electrico-mechanical effects of calcium overload have been studied in cardiac papillary muscles of young adult and senescent Wistar rats driven at different rates. Action potential duration and contraction duration were found to be more prolonged in senescent than in younger animals during control conditions. Oscillatory afterpotentials and aftercontractions were more frequent in senescent than in younger rats during high calcium perfusion. Triggered activity was induced in senescent fibers but not in younger ones. Resting tension increased more in senescent fibers whereas the peak tension was not different in the two groups. It is concluded that aging is associated with a reduced capacity of the cardiac cells to handle an increased calcium load.
Di Gennaro
M
M
Cattedra di Geriatria, Università Cattolica del Sacro Cuore, Rome, Italy.
Sgadari
A
A
Pahor
M
M
Bernabei
R
R
Carbonin
P U
PU