Changes in the hepatic capacity of urea-N synthesis, galactose elimination and antipyrine clearance following 70% hepatectomy in the rat.

The capacity of urea-N synthesis (CUNS), galactose elimination capacity (GEC), and antipyrine clearance (APC) was investigated in rats 0, 3, 6, 24, 96, and 240 h after 70% hepatectomy. Sham-operated animals were used as controls. The CUNS was assessed during alanine infusion as urea accumulation in total body water, corrected for intestinal hydrolysis, GEC was measured during constant galactose infusion, and APC by the one-sample method. Immediately after the 70% hepatectomy, CUNS was reduced from 8.9 +/- 2.4 to 3.9 +/- 1.1 mumol (min X 100 g body wt)-1 (mean +/- SD, p less than 0.05), that is, 0.43 times the control value. The corresponding reduction in liver weight was 0.36. After 6 h CUNS rose to 0.62 times the control values versus 0.36 for the liver weight. The recovery of GEC and APC was slower than the recovery of the liver weight, and was only restored to 0.81 and 0.59 times the control value (p less than 0.05), respectively, after 240 h. This study demonstrates that after partial hepatectomy the capacity of urea-N synthesis rate is increased, that is, a compensatory hyperfunction of the remnant liver, and that this function is restored to normal more rapidly than other measures of functional liver mass.