[Coronary circulation under alpha-adrenergic blockade].

In canine experiments with coronary catheterization and perfusion, catheterization of the heart cavities and great vessles, and with thermodilution it was demonstrated that the alpha-adrenergic blocker Phentolamine causes a regular flow resistance in the coronary vessels. The maximal depressor effect was observed with 0.3 mg/kg (intravenously), and it did not grow under higher doses of the drug. The reduction of coronary resistance under the effect of Phentolamine was realized, firstly, by way of a moderate activation of myocardial beta-receptors, and secondly, by way of a specific block of alpha-adrenergic receptors of the heart vessels. Phentolamine inhibited the pressor reactions of the coronaries to mesatone, adrenalin, noradrenalin, and limited the manifestations of the pressor effects in the coronary vessels during systemic sinocarotid reflexes.