Vissing J, Sonne B, Galbo H
Department of Medical Physiology B, Panum Institute, Copenhagen, Denmark.
Am J Physiol. 1988 Sep;255(3 Pt 2):R400-6. doi: 10.1152/ajpregu.1988.255.3.R400.
Hepatic glucose production (Ra) was studied in phlorizin (P)- and saline (C)-infused rats running for 35 min at 21 m/min in the postabsorptive state (series I) or 18 m/min in the fed state (series II). Phlorizin-induced increase in glucose clearance would increase or not affect Ra, depending on whether metabolic feedback mechanisms or central command from central nervous system (CNS), respectively, regulate Ra during exercise. Initial exercise-induced increases in Ra were similar in P and C rats of both series, although glucose clearance was higher and plasma glucose lower, however not hypoglycemic, in P rats. After 5 min of exercise, Ra remained similar in P and C rats in series I, whereas in series II, Ra increased almost twice as much in P compared with C rats. In both series muscle glycogenolysis and lipolysis were higher in P than in C rats. The results suggest a central command regulation of Ra from CNS motor centers and that this primary setting may be modulated by metabolic feedback mechanisms. Hypoglycemia is not needed to activate metabolic feedback. A variety of substrates rather than glucose specifically is mobilized by metabolic feedback mechanisms associated with decreased glucose availability.
在处于空腹状态（系列I）以21米/分钟速度跑步35分钟或处于进食状态（系列II）以18米/分钟速度跑步的大鼠中，研究了肝葡萄糖生成率（Ra），这些大鼠分别输注了根皮苷（P）或生理盐水（C）。根皮苷诱导的葡萄糖清除率增加是否会增加或不影响Ra，这分别取决于运动期间代谢反馈机制或中枢神经系统（CNS）的中枢指令是否调节Ra。两个系列的P组和C组大鼠运动开始时诱导的Ra增加相似，尽管P组大鼠的葡萄糖清除率更高且血糖更低，但未出现低血糖。运动5分钟后，系列I中P组和C组大鼠的Ra保持相似，而在系列II中，P组大鼠的Ra增加几乎是C组大鼠的两倍。在两个系列中，P组大鼠的肌肉糖原分解和脂肪分解均高于C组大鼠。结果表明，CNS运动中枢对Ra有中枢指令调节，并且这种主要调节可能会受到代谢反馈机制的调节。激活代谢反馈不需要低血糖。与葡萄糖可用性降低相关的代谢反馈机制动员的是多种底物而非特定的葡萄糖。
