TEMPORAL RELATIONSHIPS BETWEEN URINARY SALT RETENTION AND ALTERED SYSTEMIC HEMODYNAMICS IN DOGS WITH EXPERIMENTAL CIRRHOSIS

Abstract

The relationship between urinary Na retention and systemic hemodynamics in dogs with experimental portal cirrhosis induced by the sporadic feeding of dimethylnitrosamine was studied. Na handling was studied by balance techniques; plasma volume was measured serially with Evan''s blue; and CO [cardiac output], blood pressure, CVP [central venous pressure] and PVR [peripheral vascular resistance] were monitored through indwelling catheters. Six dogs were studied while standing quietly in a Pavlov sling, in a serial fashion starting 4 wk after drug administration and continuing for 3 mo. thereafter, until all dogs developed cirrhosis and ascites. Urinary Na retention commenced generally 9-12 wk following the initiation of treatment, but renal perfusion remained normal. Plasma volume expansion was noted within 1 wk following onset of Na retention. Ascites were generally detected about 2 wk following initiation of Na retention. No alteration in CO or PVR was detected until ascites were present in significant amounts. At that time, CO rose and PVR fell about 20%. ABP [arterial blood pressure] tended to fall during the period of observation, but insignificantly. The initiation of Na retention in this canine model does not depend on antecedent changes in CO or PVR.