Marker J C, Hirsch I B, Smith L J, Parvin C A, Holloszy J O, Cryer P E
Division of Endocrinology, Diabetes, and Metabolism, Washington University School of Medicine, St. Louis, Missouri 63110.
Am J Physiol. 1991 May;260(5 Pt 1):E705-12. doi: 10.1152/ajpendo.1991.260.5.E705.
To assess the role of catecholamines in the prevention of hypoglycemia during moderate exercise (approximately 60% peak O2 consumption for 60 min), normal humans were studied with combined alpha- and beta-adrenergic blockade and with adrenergic blockade while changes in insulin and glucagon were prevented with the islet clamp technique (somatostatin infusion with insulin and glucagon infused at fixed rates). The results were compared with those from an islet clamp alone study. In contrast to a comparison study (saline infusion), adrenergic blockade resulted in a small initial decrease in plasma glucose during exercise, from 5.0 +/- 0.2 to 4.4 +/- 0.2 mmol/l (P less than 0.01), but the level then plateaued. There was a substantial exercise-associated decrement in plasma glucose when insulin and glucagon were held constant, i.e., from 5.5 +/- 0.2 to 3.4 +/- 0.2 mmol/l (P less than 0.0001), but the level again plateaued. However, when insulin and glucagon were held constant and catecholamine actions were blocked simultaneously, progressive hypoglycemia, to 2.6 +/- 0.6 mmol/l (P less than 0.001), developed during exercise. Hypoglycemia was the result of an absent increase in glucose production and an exaggerated initial increase in glucose utilization. Thus we conclude that sympathochromaffin activation plays a minor role when insulin and glucagon are operative, but a catecholamine, probably epinephrine, becomes critical to the prevention of hypoglycemia during exercise when changes in insulin and glucagon do not occur.
为评估儿茶酚胺在中等强度运动（约60%峰值耗氧量，持续60分钟）期间预防低血糖中的作用，对正常人进行了联合α和β肾上腺素能阻滞剂阻断以及肾上腺素能阻滞剂阻断的研究，同时采用胰岛钳夹技术（以固定速率输注生长抑素、胰岛素和胰高血糖素）防止胰岛素和胰高血糖素发生变化。将结果与单独进行胰岛钳夹研究的结果进行比较。与对照研究（输注生理盐水）相比，肾上腺素能阻滞剂导致运动期间血浆葡萄糖最初略有下降，从5.0±0.2 mmol/L降至4.4±0.2 mmol/L（P<0.01），但随后水平趋于平稳。当胰岛素和胰高血糖素保持恒定时，运动期间血浆葡萄糖出现显著下降，即从5.5±0.2 mmol/L降至3.4±0.2 mmol/L（P<0.0001），但水平再次趋于平稳。然而，当胰岛素和胰高血糖素保持恒定且儿茶酚胺作用同时被阻断时，运动期间出现进行性低血糖，降至2.6±0.6 mmol/L（P<0.001）。低血糖是由于葡萄糖生成未增加以及葡萄糖利用最初过度增加所致。因此，我们得出结论，当胰岛素和胰高血糖素起作用时，交感嗜铬细胞激活起次要作用，但当胰岛素和胰高血糖素不发生变化时，一种儿茶酚胺（可能是肾上腺素）对于运动期间预防低血糖至关重要。
