[Histologic aspects of intramyocardial arterioles, during drug induced vasodilation and vasoconstriction]

The author studied the histologic features of the intramyocardial arterioles of the dog, under various situations of vasomotricity induced by drugs. Hemodynamics were evaluated by the pressures of the right atria and the aorta and through the coronary flow. The histologic studies were done on biopsy specimens taken from the anterior left ventricular wall. The results were 1.1 (0.7-1.3) for the control state, 0.3 (0.1-0.6) for situations of vasodilatation and 1.5 (1.1-1.8) during vasoconstriction. The authors believe that the histologic appearance of the intramyocardial vessels, in the various situations of vasomotricity may represent the lower and upper limits of the autoregulatory curve.