Metabolic flux measurements across portal drained viscera, liver, kidney and hindquarter in mice

A method was developed to measure metabolic fluxes across either portally-d rained viscera (PDV) and liver or kidney and hindquarter (HQ) in anesthetiz ed mice. The method includes a primed-constant infusion of ketamine-medetom idine anaesthesia to stabilize the mice for the surgical procedures. For me asurement of metabolic fluxes across PDV and liver, blood sampling catheter s were inserted in the carotid artery, portal vein and hepatic vein and inf usion catheters in the jugular vein and mesenteric vein. For measurement of metabolic flux across kidney and HQ, blood sampling catheters were inserte d in the carotid artery, renal vein and caval vein and infusion catheters i n the jugular vein and abdominal aorta. C-14-PAH was infused to enable plas ma flow measurement using an indicator dilution method. In addition, we dev eloped a blood sampling procedure without waste of blood. We measured plasma flow and metabolic fluxes across PDV, liver, kidney and HQ. Mean plasma flow in post-absorptive mice was: PDV: 0.9 +/- 0.2, liver: 1.2 +/- 0.3, kidney: 1.0 +/- 0.1, HQ: 1.1 +/- 0.3 ml/10 g body weight (b.w. )/min. Significant glutamine release by the HQ and uptake of glutamine by t he kidney and PDV was observed. In PDV, citrulline is produced from glutami ne and is in turn used by the kidney for the production of arginine. In con clusion, the described model enables measurement of metabolic fluxes across PDV, liver, kidney and HQ in mice. The availability of such a small animal model allows the potential for measuring metabolic parameters in transgeni c and knockout mice, and therefore may lead to an important refinement in m etabolic research.