Freetly H C, Ferrell C L
Roman L. Hruska U.S. Meat Animal Research Center, ARS, USDA, Clay Center, Nebraska 68933, USA.
J Anim Sci. 1998 Dec;76(12):3133-45. doi: 10.2527/1998.76123133x.
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 numbers 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. Blood 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 not pregnant and in six ewes with single and 11 ewes with twin lambs. Additional measurements were taken 103, 82, 61, 39, 19, and 6 d before parturition. 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. In ewes with twins, premating net hepatic glucose release was 36.8 +/- 2.7 mmol/h, and 19 d before parturition it was 47.4 +/- 2.8 mmol/h. Net PDV lactate release did not differ with litter size (P = .58) or days from parturition (P = .14; 9.7 +/- 4.6 mmol/h). Net lactate uptake by the liver increased in pregnant ewes as the pregnancy progressed (P < .001). The hepatic extraction ratio for lactate increased in late pregnancy (P = .02). Net PDV and hepatic release of acetate and propionate were not different with litter size or days from parturition. Hepatic extraction ratios of VFA did not differ with litter size or day from parturition. The patterns of change in hepatic metabolite fluxes are similar to the patterns of change in gravid uterus metabolite uptake. Hepatic lactate uptake seems to be regulated during pregnancy.
我们这项研究的目的是确定怀有不同数量胎儿的母羊门静脉引流内脏（PDV）和肝脏的营养物质通量模式。将导管插入母羊的肝门静脉、肝静脉分支、肠系膜静脉和腹主动脉。在接触公羊之前，测定通过PDV和肝脏的血流量和净营养物质释放量。然后让母羊交配，结果有两只母羊未怀孕，六只母羊怀有单胎羔羊，11只母羊怀有双胎羔羊。在分娩前103、82、61、39、19和6天进行了额外测量。PDV的葡萄糖净释放量与零无差异（-0.4±8.4 mmol/h；P = 0.58）。怀有单胎的母羊，配种前肝脏葡萄糖净释放量为34.4±2.4 mmol/h，分娩前19天为46.2±3.8 mmol/h。怀有双胎的母羊，配种前肝脏葡萄糖净释放量为36.8±2.7 mmol/h，分娩前19天为47.4±2.8 mmol/h。PDV的乳酸净释放量与产仔数（P = 0.58）或距分娩天数（P = 0.14；9.7±4.6 mmol/h）无关。随着怀孕进程的推进，怀孕母羊肝脏对乳酸的净摄取量增加（P < 0.001）。怀孕后期肝脏对乳酸的提取率增加（P = 0.02）。PDV和肝脏中乙酸盐和丙酸盐的净释放量与产仔数或距分娩天数无关。挥发性脂肪酸（VFA）的肝脏提取率与产仔数或距分娩天数无关。肝脏代谢物通量的变化模式与妊娠子宫代谢物摄取的变化模式相似。怀孕期间肝脏对乳酸的摄取似乎受到调节。
