EFFECTS OF ACUTE REDUCTION OF CARDIAC OUTPUT ON THE RENAL CIRCULATION OF THE DOG 1

Abstract

Acute reduction of cardiac output was produced in dogs by means of graded constriction of the pulmonary artery. Changes in arterial and central venous pressures were measured by means of optical manometers in some expts. and by mercury and water manometers in others. Alterations in cardiac output were detd. by the Fick procedure, and renal circulatory data obtained by clearance technics. Exptl. observations were made during pre-operative and post-operative control periods, during periods of acutely reduced cardiac output, and during subsequent recovery periods. Effective renal blood flow was diminished by compression of the pulmonary artery, but to a lesser degree than the cardiac output, resulting in a significant elevation of the renal fraction. Mean arterial pressure fell slightly, and in no case below 80 mm. Hg. Glomerular filtration rate remained unchanged or decreased somewhat, producing a rise in the filtration fraction. Acute reduction of the cardiac Output elicited a relatively large increase in the total peripheral resistance, but only a comparatively slight augmentation of the total renal resistance. Analysis of the changes in renal resistance by Lamport''s formulae indicates a significant increase in efferent arteriolar resistance countered by a decrease in afferent resistance.