Effect of glucocorticolids on catecholamine synthesis in the heart and adrenals of rats in the presence of physical fatigue

: The influence of the adrenal cortex hormones on the catecholamine synthesis in the adrenal glands and the heart of rats following prolonged swimming (8 hours) was studied. Catecholamine synthesis after the incubation of the adrenal glands and heart in the presence of L-tyrosine was sharply inhibited after swimming. Addition of hydrocortisone or prednisolone in vitro (50 microgram per sample) and also administration of these hormones in vivo (50 mg/kg intramuscularly, 3 hours before decapitation) increased catecholamine synthesis in the adrenal glands of swimming, but not of intact rats. After the incubation of the adrenal glands of swimming rats in the presence of L-DOPA and L-noradrenaline, catecholamine synthesis was depressed in comparison with intact animals, and it failed to be restored on addition of glucocorticoids. No stimulating effect of aldosterone on catecholamine synthesis in the adrenal glands in the presence of L-tyrosine was revealed. Catecholamine synthesis was inhibited and not restored under the effect of glucocorticoids in vitro and in vivo after the incubation of the heart tissue of swimming rats in the presence of L-tyrosine and L-DOPA. A conclusion was drawn that glucocorticoid promoted restoration of catecholamine synthesis inhibiteds in case of strong physical fatique at the stage of tyrosin-hydroxylase.