Huntington G B, Reynolds C K
J Nutr. 1987 Jun;117(6):1167-73. doi: 10.1093/jn/117.6.1167.
Oxygen (O2) uptake and net metabolite flux by portal-drained viscera (PDV) and hepatic (HEP) tissues have been quantitated in vivo by measuring blood flow and arteriovenous concentration differences in cattle with chronic indwelling catheters in appropriate blood vessels. Results from use of this technique show that PDV of cattle account for 8-10% of body tissue, but 18-25% of whole animal O2 consumption. Similarly, HEP tissues account for 1-2% of body tissues, but more of whole animal O2 consumption than PDV. Glucose, volatile fatty acids (VFA), glutamate and glutamine are used as substrates by PDV; ketones, alanine and glycine are major products of PDV metabolism that are transported to HEP tissues along with absorbed VFA, ammonia, amino acids and other products of digestion. Most amino acids, L-lactate, propionate and butyrate and ammonia in blood from PDV are removed by HEP tissues, which in turn release glucose, glutamate, branched-chain amino acids, ketones, acetate and urea to peripheral blood. Net HEP flux of glucose measured by this technique is compatible with glucose requirements for lactation and other metabolism; similarly, HEP uptake of ammonia and alpha-amino N can account for 95% of HEP release of urea N. The technique is a powerful tool for quantitation of intermediary metabolism.
通过测量慢性留置导管的牛体内适当血管的血流量和动静脉浓度差，对门静脉引流内脏（PDV）和肝脏（HEP）组织的氧气（O₂）摄取和净代谢物通量进行了定量分析。使用该技术的结果表明，牛的PDV占身体组织的8 - 10%，但占全动物氧气消耗量的18 - 25%。同样，HEP组织占身体组织的1 - 2%，但在全动物氧气消耗中所占比例比PDV更多。葡萄糖、挥发性脂肪酸（VFA）、谷氨酸和谷氨酰胺被PDV用作底物；酮体、丙氨酸和甘氨酸是PDV代谢的主要产物，它们与吸收的VFA、氨、氨基酸和其他消化产物一起被转运到HEP组织。PDV血液中的大多数氨基酸、L - 乳酸、丙酸、丁酸和氨被HEP组织清除，HEP组织继而向外周血液释放葡萄糖、谷氨酸、支链氨基酸、酮体、乙酸盐和尿素。通过该技术测量的HEP葡萄糖净通量与泌乳和其他代谢的葡萄糖需求相符；同样，HEP对氨和α - 氨基氮的摄取可占HEP尿素氮释放量的95%。该技术是定量中间代谢的有力工具。
