Influence of partial hepatectomy on the renal response to isotonic saline loads in conscious rats.

Abstract

1. Isotonic saline loads equivalent to 10, 5, and 2.5% of body wt were administered intravenously to partially hepatectomized (PH) and to shamoperated (C), conscious male rats. Urine flow and excretion rates for sodium, potassium, and endogenous creatinine were determined before, during, and for five 30-min periods after the saline infusion. 2. The renal response to isotonic saline loads of 10 and 5% of body wt was not significantly altered by partial hepatectomy. 3. During loading to 2.5% of body wt and for all periods thereafter, sodium exeretion was significantly lower for the PH than for the C group while urine flow and potassium excretion were depressed for a shorter duration. Glomerular filtration rate and filtered sodium load were practically identical for the two groups while the tubular rejection fraction for sodium was significantly depressed in the PH group. Changes in hematocrit and plasma protein concentration, additional surgical trauma, blood loss in the excised portion of the liver, and excess aldosterone were ruled out as possible factors contributing to the depressed sodium excretion. 4. These experiments indicate that the degre of extracellular fluid volume expansion is an important factor in demonstrating an effect of partial hepatactomy on sodium excretion and suggest possible involvement of the liver in the enhanced natriuresis accompanying volume expansion.