Effects of the administration of angiotensin II on cardiac glycogen metabolism in the rat

Abstract

Changes in glycogen metabolism after an intravenous injection of angiotensin II were investigated in the left and right ventricles of the rat heart, as a function of location within the ventricular wall. Hearts were cut into 100-microns thin section, all of which were analysed for glycogen content, glucose incorporation into glycogen and 2-deoxyglucose uptake and phosphorylation after the intravenous injection of 14C-labelled sugar. In control hearts, glycogen levels were uniform across the wall in both ventricles, while the rate of sugar uptake and phosphorylation, and that of glucose incorporation into glycogen, were significantly higher in the subendocardial myocardium of the left ventricular wall. After angiotensin II administration, heart glycogen levels decreased slightly in the left, but not in the right ventricle, while 2-deoxyglucose uptake and phosphorylation, and glucose incorporation into glycogen, increased 2,5- and 5-fold, respectively. With regard to the distribution across the wall of the left ventricle after angiotensin administration, glycogen levels and glucose incorporation into glycogen were uniformly distributed, whereas sugar phosphorylation was still higher in the subendocardium.