[The role of reflexes from the coronary vessels in the regulation of the circulatory system]

Abstract

In the experiments on dogs was investigated participation of coronary vessels in the reflexive regulation of the circulatory system. Electrical, hemodynamic and metabolic heart functions, pressures, and flow in peripheral vessels were measured. Hemodynamic reactions obtained by changes of the perfusion pressure and gas composition of blood in the left coronary artery and in coronary sinus were compared with the activity of cervical baro and chemoreceptors. Results of this investigation indicate that responses initiated by the changes in coronary perfusion pressure were manyfold smaller. Occlusion or decrease of the pressure in the left coronary artery caused pressor effect, which was diminish by myocardial ischemia. Declamping or increase of the perfusion pressure in the left coronary artery was leading to decrease of systemic arterial pressure. This response was next replaced by the pressor effect caused by the rapid myocardial blood flow. In the systemic hypertension blood flow changes in the left coronary artery caused smaller effects than in the normotension. In the hypertension increase of the coronary perfusion pressure initiated significant pressor reaction. Opposite effect was observed with the decrease of coronary perfusion pressure. Decrease of coronary oxygen content moderate pressor reaction in the systemic normotension also in hypertension. In systemic hypotension the depressor reactions was observed. Elevation of the coronary sinus perfusion pressure was correlated with the decrease in the systemic arterial pressure with significant bradycardia. Additional coronary sinus blood arterialisation caused pressor effect in systemic pressure. It possible that the coronary vessels in dogs are the source of the circulatory reflexes which seems possess essential physiological role.