Effect of nitroglycerin with and without systemic hypotension on canine regional myocardial tritiated water deposition.

ABSTRACT

A marked alteration in the transmural distribution of left ventricular blood flow, with a relative increase in subendocardial and mid-wall flows, but with no change in the distribution of the relative blood flow to the two ventricles occurred when nitroglycerin was administered and the systemic arterial blood pressure in the upper body maintained near control levels in anaesthetized, open-chested dogs. The relative increase in subendocardial and mid-wall flows may have resulted from a direct action of nitroglycerin on the coronary vasculature. On the other hand, the intravenous administration of nitroglycerin, when followed by the hypotension which it produces, did not alter the transmural distribution of blood flow in the left ventricle of the dog. Blood flow to the right ventricle relative to flow to the left ventricle increased in this situation.