Hepatic glucose disposition during concomitant portal glucose and amino acid infusions in the dog
Moore, M.C.; Flakoll, P.J.; Hsieh, P.S.; Pagliassotti, M.J.; Neal, D.W.; Monohan, M.T.; Venable, C.; Cherrington, A.D.
American Journal of Physiology 274(5): E893-E902
1998
ISSN/ISBN: 0002-9513 PMID: 9612248 Document Number: 488540
The effect of concomitant intraportal infusion of glucose and gluconeogenic amino acids (AA) on net hepatic glucose uptake (NHGU) and glycogen synthesis was examined in 42-h-fasted dogs. After a basal period, there was a 240-min experimental period during which somatostatin was infused continuously into a peripheral vein and insulin and glucagon (at 3-fold basal and basal rates, respectively) and glucose (18.3 mumolcntdotkg-1cntdotmin-1) were infused intraportally. One group (PoAA, n = 7) received an AA mixture intraportally at 7.6 mumolcntdotkg-1cntdotmin-1, whereas the other group (NoAA, n = 6) did not receive AA. Arterial blood glucose concentrations and hepatic glucose loads were the same in the two groups. NHGU averaged 4.8 +- 2.0 (PoAA) and 9.4 +- 2.0 (NoAA) mumolcntdotkg-1cntdotmin-1 (P < 0.05), and tracer-determined hepatic glucose uptake was 4.6 +- 1.6 (PoAA) and 10.0 +- 1.7 (NoAA) mumol cntdot kg-1 cntdot min-1 (P < 0.05). AA data for PoAA and NoAA, respectively, were as follows: arterial blood concentrations, 1,578 +- 133 vs. 1,147 +- 86 muM (P < 0.01); hepatic loads, 56 +- 3 vs. 32 +- 4 mumol cntdot kg-1 cntdot min-1 (P < 0.01); and net hepatic uptakes, 14.1 +- 1.4 vs. 5.6 +- 0.4 mumolcntdotkg-1 cntdot min-1 (P < 0.01). The rate of net hepatic glycogen synthesis was 7.5 +- 1.9 (PoAA)vs. 10.7 +- 2.3(NoAA)mumol cntdot kg-1 cntdot min-1 (P = 0.1). In a net sense, intraportal gluconeogenic amino acid delivery directed glucose carbon away from the liver. Despite this, net hepatic carbon uptake was equivalent in the presence and absence of amino acid infusion.