[Role of adrenergic regulation in the genesis of myocardial ischemia]

The role of altered adrenergic regulation in the development of myocardial pathology was studied in dog experiments. Activation of the sympathetico-adrenal system was induced by electrostimulation of the sympathetic tonic cardiac nerve in the first experimental series and by intravenous infusion of exogenous noradrenaline (NA) in a dose of 1 microgram/kg/min in the second series. A positive inotropic response of the heart occurred in both series. Comparison of the effect of nerve stimulation with the effect of exogenous NA showed them to be essentially different. The NA-mediator secreted in stimulation of the nerve contributed to the development of coronarogenic myocardial ischemia which was confirmed by ECG and the results of study of the coronary blood flow. Infusion of NA from an ampule in the above-mentioned doses failed to produce an effect on the alpha-receptors of the coronary vessels, but by activating the beta 2-receptors of the coronary arteries facilitated their dilatation and thus increased the blood flow in them. The functional relationship between the sympathetic tonic nerve and the alpha-adrenoreceptors of the coronary arteries and between the humoral catecholamines and their beta 2-adrenoreceptors is shown.