Author:
Sumida Ken D.,Urdiales Jerry H.,Donovan Casey M.
Abstract
The impact of reduced hepatic flow on lactate uptake and gluconeogenesis was examined in isolated glucagon-stimulated perfused livers from 24-h-fasted rats. After surgical isolation, livers were perfused (single pass) for 30 min with Krebs-Henseleit (KH) bicarbonate buffer, fresh bovine erythrocytes (hematocrit ∼20%), and no added substrate. After this “washout” period, steady-state perfusions were initiated with a second reservoir containing the KH buffer, bovine erythrocytes, [U-14C]lactate (10,000 dpm/ml), lactate (2.5 mM), and glucagon (250 μg/ml). Perfusion flow rate was adjusted to one of five rates (i.e., 1.8, 2.7, 3.9, 7.4, and 11.0 ml·min−1·100 g body wt−1). After the perfusion, the liver was dissected out and weighed so as to establish the actual flow rate per gram of liver. The resulting flow rates ranged from 0.52 to 4.03 ml·min−1·g liver−1. As a function of flow rate, lactate uptake rose in a hyperbolic fashion to an apparent plateau of 2.34 μmol·min−1·g liver−1. Fractional extraction (FX) of lactate from the perfusate demonstrated an exponential decline with increased flow rates ( r = 0.97). At flow rates above 1.0 ml·min−1·g liver−1, adjustments in FX compensated for changes in lactate delivery, resulting in steady rates of lactate uptake and gluconeogenesis. Below 1.0·min−1·g liver−1the increased FX was unable to compensate for the decline in lactate delivery and lactate uptake declined rapidly. Gluconeogenesis demonstrated similar kinetics to lactate uptake, reflecting its dominant role among pathways for lactate removal under the current conditions.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology,Endocrinology, Diabetes and Metabolism
Cited by
7 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献