Casado J, Fernández-López J A, Argilés M J, Alemany M
Departament de Bioquímica i Fisiologia, Universitat de Barcelona, Spain.
Mol Cell Biochem. 1992 Jul 6;113(1):33-41. doi: 10.1007/BF00230883.
An oral gavage of either 3, 1, or 0.1 mmoles of glucose was given to rats under standard feeding conditions or food deprived for 24 hr. The blood flow of the portal and suprahepatic veins as well as the hepatic balances for glucose, lactate, alanine and pyruvate were estimated. In fed rats, after the administration of an oral 3 mmoles load, the liver actually released 310 mumoles of glucose and 90 of lactate, amounts that could be accounted for by the uptake of alanine (148 mumoles) and small loss of glycogen (275 mumoles of glycosyl residues). In starved rats, however, the liver took a very high proportion (c. 71%) of the glucose absorbed, both as glucose (780 mumoles), lactate and pyruvate (892 mumoles) or alanine (134 mumoles). The synthesis of glycogen was considerably limited, accounting for only 205 mumoles, and leaving practically one mmol of glucose equivalent energy available for liver function and the synthesis of other compounds. Practically all glycogen was synthesized directly from glucose, since the synthesis from 3 C carriers was less than a 5%. Smaller gavages (1 or 0.1 mmoles) resulted in a much lower liver uptake activity. The strikingly different activity of the liver with respect to the available glucose and 3 C fragments could not be explained alone by the circulating levels of these compounds, suggesting a very deep influence of the intestine in hepatic function. The liver plays a very passive role in fed animals, with a very small involvement in the disposal of a glucose load, whereas it takes on an important role when the overall availability of energy is diminished.
在标准喂养条件下或禁食24小时后，给大鼠经口灌胃3、1或0.1毫摩尔的葡萄糖。测定门静脉和肝上静脉的血流量以及肝脏对葡萄糖、乳酸、丙氨酸和丙酮酸的平衡。在喂食的大鼠中，口服3毫摩尔负荷后，肝脏实际上释放了310微摩尔的葡萄糖和90微摩尔的乳酸，这些量可以通过丙氨酸的摄取（148微摩尔）和糖原的少量损失（275微摩尔糖基残基）来解释。然而，在饥饿的大鼠中，肝脏摄取了吸收葡萄糖的很大一部分（约71%），包括葡萄糖（780微摩尔）、乳酸和丙酮酸（892微摩尔）或丙氨酸（134微摩尔）。糖原的合成受到很大限制，仅占205微摩尔，实际上有一毫摩尔葡萄糖当量的能量可用于肝功能和其他化合物的合成。几乎所有的糖原都是直接由葡萄糖合成的，因为由三碳载体合成的糖原不到5%。较小剂量的灌胃（1或0.1毫摩尔）导致肝脏摄取活性低得多。肝脏对可用葡萄糖和三碳片段的活性差异显著，不能仅用这些化合物的循环水平来解释，这表明肠道对肝功能有非常深刻的影响。在喂食的动物中，肝脏起着非常被动的作用，对葡萄糖负荷的处理参与很少，而当能量的总体可用性降低时，它则发挥重要作用。
