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Immobilization stress with duration of 6, 12 and 24 hours was induced in rats of Wistar strain. The rats of the control group were without food and water for the same periods of time. The active form a of glycogen phosphorylase, total enzymic activity a-b and the percentage of the active form of the total enzymic activity in the myocardium of the left ventricle, right ventricle and intraventricular septum were determined. There were no statistically significant differences in the activity of phosphorylase a and in the total enzymic activity between the control and experimental animals on the sixth hour since the onset of the study. The activity of both forms of the enzyme in the right ventricle and septum was higher in comparison with that of the control animals after 12 hours of immobilization. The enzymic activity was reduced in comparison with that of the control animals after 24 hours of immobilization. It could be assumed that metabolic adaptive mechanism of the cardiac muscle improve conditions for formation of energy from carbohydrate sources.

The authors examined the activity of the enzyme phosphorilase in the myocardium of rats with spontaneous hypertension of the Okamoto Aoki type and of Wistar rats with experimental metacorticoid hypertension. They found higher basal activity of phosphorilase "a" in the both groups of hypertonic rats. After treatment of rats with isoprenaline in a dose of I mg/kg, administered intraperitonealy, the phosphorilase "a" in the myocardium of hypertensive animals was activated to a degree equal to that of the normotensive rats. This correlated also with the maximal isoprenaline chronotropic response in the both groups of hypertensive rats. The authors discussed the possible causes and mechanisms for the observed changes and effects.

Studied were the rate and mechanism of glycogen breakdown in rats treated with Salmonella abortus ovis endotoxin. It was found that tissue homogenates from treated animals showed higher glycogenolytic activity in vitro as compared with homogenates from untreated animals, which demonstrated the direct mechanism of endotoxin action. The higher lytic activity with treated animals seemed to be associated with the higher activity of glycogen-phosphorylase, which showed peak values at the third hour following treatment. The higher activity of glycogen-phosphorylase was, in turn, the result of the enzyme reactivation under the effect of the endotoxin, and was not linked with the synthesis or new enzyme molecules.