Calcium exchangeable fraction of sarcoplasmic reticulum in hypertrophic dog heart.

Cardiac hypertrophy in weaning beagle dogs was obtained by a loose aortic banding with a 10-mm Dacron-Teflon band, positioned 1 cm distal from the aortic valve 9 months later all animals developed left ventricular hypertrophy without signs of heart failure. Sarcoplasmic reticulum proteins as well as their calcium-exchanging properties were measured in hypertrophic heart and in those from sham-operated control animals. The calcium exchangeable fraction for hypertrophic heart was found to the higher than for controls, while sarcoplasmic reticulum proteins obtained from hypertrophic hearts were lower than those obtained from control animals. It is probable that the increase in the calcium exchangeable fraction could represent a mechanism of compensation in an early stage of the development of the hypertrophic heart whose sarcoplasmic reticulum fraction is not adequately developed.