Net flux of glucose, lactate, volatile fatty acids, and nitrogen metabolites across the portal-drained viscera and liver of pregnant ewes

Our objective for this study was to determine the pattern of nutrient flux across the portal-drained viscera (PDV) and liver in ewes with varying numb ers of fetuses. Catheters were placed in the hepatic portal vein, a branch of the hepatic vein, a mesenteric vein, and the abdominal aorta of ewes. Bl ood flow and net nutrient release across the PDV and liver were determined before exposure to rams. Ewes were then mated, which resulted in two ewes n ot pregnant and in six ewes with single and II ewes with twin lambs. Additi onal measurements were taken 103, 82, 61, 39, 19, and 6 d before parturitio n. Net PDV glucose release did not differ from zero (-.4 +/- 8.4 mmol/h; P = .58). In ewes with singles, premating net hepatic glucose release was 34. 4 +/- 2.4 mmol/h, and 19 d before parturition it was 46.2 +/- 3.8 mmol/h. I n ewes with twins, premating net hepatic glucose release was 36.8 +/- 2.7 m mol/h, and 19 d before parturition it was 47.4 +/- 2.8 mmol/h. Net PDV lact ate release did not differ with Litter size (P = .58) or days from parturit ion (P = .14; 9.7 +/- 4.6 mmol/h). Net lactate uptake by the liver increase d in pregnant ewes as the pregnancy progressed (P < .001). The hepatic extr action ratio for lactate increased in late pregnancy(P = .02). Net PDV and hepatic release of acetate and propionate were not different with litter si ze or days from parturition. Hepatic extraction ratios of VFA did not diffe r with litter size or day from parturition. The patterns of change in hepat ic metabolite fluxes are similar to the patterns of change in gravid uterus metabolite uptake. Hepatic lactate uptake seems to be regulated during pre gnancy.