STUDIES ON DIGITALIS. I. DIRECT EFFECTS ON PERIPHERAL VASCULAR RESISTANCE

Abstract

The effects of acetylstrophanthidin, ouabain, and lanatoside C on peripheral vascular resistance were studied in 46 dogs in which cardiac action was excluded by the use of cardiopulmonary bypass. At a constant perfusion rate a significant elevation of arterial pressure occurred in each instance and reflected an augmentation of peripheral vascular resistance. This elevation of arterial pressure was not abolished by ganglionic blockade or adrenalectomy and was not modified by splanchnic arterial ligation. The injection of acetylstrophanthidin into the constantly perfused lower aorta of 4 dogs resulted in a pressor response limited to this portion of the vascular bed, while injection into the upper segment of 3 dogs produced a reflex fall in pressure in the lower segment. These experiments support the view that a direct action of digitalis on arteriolar smooth muscle is responsible for the digitalis-induced increase in peripheral vascular resistance.