One of the physiological roles of glutamine is as a precursor for DNA synthesis. The aims of this study were to determine (1) whether glutamine-supplemented total parenteral nutrition (TPN) enhanced DNA and protein synthesis in the liver and (2) whether glutamine uptake was increased following partial hepatectomy in rats. Male Donryu rats (n = 59; body weight, 250-275 g) were randomized into four groups: (1) sham operation + standard TPN solution (C-STPN); (2) C + glutamine-supplemented TPN (C-GTPN); (3) 70% partial hepatectomy + STPN (H-STPN); (4) partial hepatectomy + GTPN (H-GTPN). On Day 0, rats underwent either a sham operation or 70% partial hepatectomy and concomitantly were catheterized in the jugular vein. TPN was begun immediately after the surgery. GTPN was isocaloric and isonitrogenous with STPN and 25% of total nitrogen was given as glutamine. On Day 2, the animals were sacrificed after either a continuous infusion of 1-14C-leucine or a bolus i.v. injection of bromodeoxyuridine. The rate of hepatic regeneration was enhanced with glutamine supplementation (H-STPN, 60.8 +/- 1.6% vs H-GTPN, 66.3 +/- 2.0, P < 0.05) due to an increase in protein synthesis in the liver (H-STPN, 134.0 +/- 10.3%/day vs H-GTPN, 160.9 +/- 6.9, P < 0.05) and DNA synthesis in hepatocytes (H-STPN, 23.1 +/- 2.5% vs H-GTPN, 31.4 +/- 2.9, P < 0.05). The uptake of glutamine by the liver was increased following hepatectomy with GTPN supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)