Fournier P A, Guderley H
Department of Biology, Laval University, Ste-Foy, Quebec, Canada.
Am J Physiol. 1993 Feb;264(2 Pt 2):R239-43. doi: 10.1152/ajpregu.1993.264.2.R239.
Although liver is thought to be the major glucose-producing organ in vertebrates, it is not the major source responsible for the accumulation of glucose in frogs during burst activity. This is indicated by the absence of significant changes in liver glycogen levels during exercise, the inability of the maximal reported rate of hepatic glucose production in vitro to account for the increase in the glucose content of the frog, and from the observation that hepatectomized and normal frogs accumulate similar amounts of glucose in their muscles and body during exercise. We conclude that most glucose that accumulates in the body during exercise originates in muscle because two-thirds of body glucose is found in muscle and because the intracellular levels of muscle glucose rise well above plasma levels. The glucose that accumulates outside muscle is also likely to originate in muscle. The most likely metabolic source of the glucose produced by muscle is the glycogen hydrolyzed by amylo-1,6-glucosidase.
尽管肝脏被认为是脊椎动物中主要的葡萄糖生成器官，但在爆发性活动期间，它并非青蛙体内葡萄糖积累的主要来源。这一点体现在运动期间肝脏糖原水平无显著变化、体外报道的肝脏最大葡萄糖生成速率无法解释青蛙体内葡萄糖含量的增加，以及观察到肝切除的青蛙和正常青蛙在运动期间肌肉和身体中积累的葡萄糖量相似。我们得出结论，运动期间体内积累的大部分葡萄糖源自肌肉，这是因为身体三分之二的葡萄糖存在于肌肉中，且肌肉内葡萄糖水平远高于血浆水平。肌肉外积累的葡萄糖也可能源自肌肉。肌肉产生的葡萄糖最可能的代谢来源是由淀粉-1,6-葡萄糖苷酶水解的糖原。
