[Corticosteroids and the adrenaline activation of glycogen phosphorylase in heart tissue]

Study of changes in the glycogen phosphorylase activity under the effect of adrenaline in the hearts of intact, adrenalectomized and sham-adrenalectomized rats demonstrated that stress increased the phosphorylase A level considerably. Against the background of these changes perfusion of the heart with 0.5.10(-7)M adrenaline produced no further elevation of the enzyme activity. Following restoration of the basal phosphorylase A to the normal level adrenaline again acquired the capacity to Phosphorylase activation. Stable absence of response of the heart tissue to adrenaline by increase of phosphorylase A activity was noted on the 5th postadrenalectomy day; this apparently followed disturbances in the potassium ions accumulation in the cells.