Horikawa S, Ishida T, Igawa K, Kawanishi K, Hartley C J, Takahara J
Department of Medicine, Kagawa Medical School, Japan.
Metabolism. 1998 Nov;47(11):1295-302. doi: 10.1016/s0026-0495(98)90295-5.
We studied the effects of both positive and negative portal venous and hepatic arterial glucose gradients on hepatic glucose uptake after the same amount of glucose was administered into the portal vein and/or hepatic artery. Studies were performed on eight unrestrained conscious dogs with catheters in the portal vein, hepatic vein, gastroduodenal artery, superior mesenteric vein, and femoral artery and Doppler flow probes on the portal vein and hepatic artery. Glucose was infused as follows: protocol 1, 55.6 micromol/kg/min into the portal vein for the first 90 minutes; protocol 2, 27.8 micromol/kg/min into both the portal vein and hepatic artery for the next 90 minutes; and protocol 3, 55.6 micromol/kg/min into the hepatic artery for the last 90 minutes. The portal venous and hepatic arterial plasma glucose gradient was 2.1+/-0.3, -3.0+/-0.5, and -7.1+/-0.6 mmol/L, the rate of hepatic glucose uptake divided by the administered glucose load was 46%+/-11%, 42%+/-10%, and 57%+/-8%, net hepatic glucose uptake was 25.4+/-5.9, 23.5+/-5.6, and 31.6+/-4.6 micromol/kg/min; and the fractional hepatic extraction of glucose was 10.7%+/-2.2%, 11.6%+/-2.5%, and 15.0%+/-2.1%, respectively (mean+/-SEM of three points at 60, 75, and 90 minutes in each protocol). The rate of hepatic glucose uptake divided by the administered glucose load, net hepatic glucose uptake, and fractional hepatic extraction of glucose did not change significantly despite the various portal venous and hepatic arterial glucose gradients. We also studied the effect of the same amount of intraportal glucose infusion for 240 minutes on net hepatic glucose uptake. From 60 to 240 minutes, net hepatic glucose uptake did not change significantly. In conclusion, the liver took up a large amount of glucose administered into the portal vein and/or hepatic artery, regardless of positive or negative portal venous and hepatic arterial glucose gradients. Augmentation of hepatic glucose uptake is not dependent on the signal of the positive or negative portal venous and hepatic arterial glucose gradient.
在向门静脉和/或肝动脉注入等量葡萄糖后，我们研究了门静脉和肝动脉葡萄糖梯度为正和为负时对肝脏葡萄糖摄取的影响。对8只未受限制的清醒犬进行了研究，这些犬的门静脉、肝静脉、胃十二指肠动脉、肠系膜上静脉和股动脉均置有导管，门静脉和肝动脉均装有多普勒血流探头。葡萄糖输注方式如下：方案1，在前90分钟内以55.6微摩尔/千克/分钟的速度注入门静脉；方案2，在接下来的90分钟内以27.8微摩尔/千克/分钟的速度同时注入门静脉和肝动脉；方案3，在最后90分钟内以55.6微摩尔/千克/分钟的速度注入肝动脉。门静脉和肝动脉血浆葡萄糖梯度分别为2.1±0.3、-3.0±0.5和-7.1±0.6毫摩尔/升，肝脏葡萄糖摄取率除以注入的葡萄糖负荷分别为46%±11%、42%±10%和57%±8%，肝脏净葡萄糖摄取量分别为25.4±5.9、23.5±5.6和31.6±4.6微摩尔/千克/分钟；葡萄糖的肝脏分数提取率分别为10.7%±2.2%、11.6%±2.5%和15.0%±2.1%（每个方案在60、75和90分钟时三个点的平均值±标准误）。尽管门静脉和肝动脉葡萄糖梯度各不相同，但肝脏葡萄糖摄取率除以注入的葡萄糖负荷、肝脏净葡萄糖摄取量以及葡萄糖的肝脏分数提取率均无显著变化。我们还研究了240分钟内等量门静脉内葡萄糖输注对肝脏净葡萄糖摄取的影响。从60分钟到240分钟，肝脏净葡萄糖摄取量无显著变化。总之，无论门静脉和肝动脉葡萄糖梯度为正或为负，肝脏都会摄取大量注入门静脉和/或肝动脉的葡萄糖。肝脏葡萄糖摄取的增加不依赖于门静脉和肝动脉葡萄糖梯度为正或为负的信号。
