Changes in coronary blood flow produced by the coronary artery occlusion

The influence of the occlusion of one coronary artery on coronary blood flow in an intact myocardium was investigated in narcotised dogs with open chest by using the crossed circulation method. Interruption of blood inflow to one of the branches of the left coronary artery under autoperfusion of the coronary bed led to a drop in the blood flow rate in the intact branch of the same artery, which was caused by decreased perfusion pressure. Stabilization of coronary perfusion pressure made it possible to detect the dilatatory reaction of the intact coronary bed to the occlusion of one of the coronary arteries. On the basis of an analysis of the dilatatory reaction, conclusions are drawn about the reflex nature of the observed phenomenon. The results of experiments with selective pharmacological blockade of both parts of the autonomous nervous system suggest that the afferent and efferent pathways run in the sympathetic nervous system.