Geor R J, Hinchcliff K W, Sams R A
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210, USA.
J Appl Physiol (1985). 2000 May;88(5):1765-76. doi: 10.1152/jappl.2000.88.5.1765.
We examined the effects of increased glucose availability on glucose kinetics and substrate utilization in horses during exercise. Six conditioned horses ran on a treadmill for 90 min at 34 +/- 1% of maximum oxygen uptake. In one trial [glucose (Glu)], glucose was infused at a mean rate of 34.9 +/- 1.1 micromol. kg(-1). min(-1), whereas in the other trial [control (Con)] an equivalent volume of isotonic saline was infused. Plasma glucose increased during exercise in Glu (90 min: 8.3 +/- 1.7 mM) but was largely unchanged in Con (90 min: 5.1 +/- 0.4 mM). In Con, hepatic glucose production (HGP) increased during exercise, reaching a peak of 38.6 +/- 2.7 micromol. kg(-1). min(-1) after 90 min. Glucose infusion partially suppressed (P < 0.05) the rise in HGP (peak value 25.8 +/- 3.3 micromol. kg(-1). min(-1)). In Con, glucose rate of disappearance (R(d)) rose to a peak of 40.4 +/- 2.9 micromol. kg(-1). min(-1) after 90 min; in Glu, augmented glucose utilization was reflected by values for glucose R(d) that were twofold higher (P < 0.001) than in Con between 30 and 90 min. Total carbohydrate oxidation was higher (P < 0.05) in Glu (187.5 +/- 8.5 micromol. kg(-1). min(-1)) than in Con (159.2 +/- 7.3 micromol. kg(-1).min(-1)), but muscle glycogen utilization was similar between trials. We conclude that an increase in glucose availability in horses during low-intensity exercise 1) only partially suppresses HGP, 2) attenuates the decrease in carbohydrate oxidation during such exercise, but 3) does not affect muscle glycogen utilization.
我们研究了运动期间葡萄糖供应增加对马的葡萄糖动力学和底物利用的影响。六匹经过训练的马在跑步机上以最大摄氧量的34±1%的强度奔跑90分钟。在一个试验组[葡萄糖（Glu）组]中，以平均速率34.9±1.1微摩尔·千克⁻¹·分钟⁻¹输注葡萄糖，而在另一个试验组[对照组（Con）]中，输注等体积的等渗盐水。运动期间，Glu组的血浆葡萄糖升高（90分钟时：8.3±1.7毫摩尔），而Con组基本未变（90分钟时：5.1±0.4毫摩尔）。在Con组中，运动期间肝葡萄糖生成（HGP）增加，90分钟后达到峰值38.6±2.7微摩尔·千克⁻¹·分钟⁻¹。输注葡萄糖部分抑制了（P<0.05）HGP的升高（峰值为25.8±3.3微摩尔·千克⁻¹·分钟⁻¹）。在Con组中，葡萄糖消失率（R(d)）在90分钟后升至峰值40.4±2.9微摩尔·千克⁻¹·分钟⁻¹；在Glu组中，在30至90分钟期间，葡萄糖R(d)值比Con组高两倍（P<0.001），这反映了葡萄糖利用率的提高。Glu组的总碳水化合物氧化高于Con组（P<0.05）（187.5±8.5微摩尔·千克⁻¹·分钟⁻¹比159.2±7.3微摩尔·千克⁻¹·分钟⁻¹），但试验之间肌肉糖原利用率相似。我们得出结论，在低强度运动期间，马体内葡萄糖供应增加：1）仅部分抑制HGP；2）减弱了此类运动期间碳水化合物氧化的减少；但3）不影响肌肉糖原的利用。
