Howlett Kirsten F, Watt Matthew J, Hargreaves Mark, Febbraio Mark A
Exercise, Muscle and Metabolism Unit, School of Health Sciences, Deakin University, Burwood, Australia.
Metabolism. 2003 Dec;52(12):1615-20. doi: 10.1016/s0026-0495(03)00330-5.
This study examined the effect of combined alpha- and beta-adrenergic blockade on glucose kinetics during intense exercise. Six endurance-trained men exercised for 20 minutes at approximately 78% of their peak oxygen consumption (Vo(2)) following ingestion of a placebo (CON) or combined alpha- (prazosin hydrochloride) and beta- (timolol maleate) adrenoceptor antagonists (BLK). Plasma glucose increased during exercise in CON (0 minutes: 5.5 +/- 0.1; 20 minutes: 6.5 +/- 0.3 mmol. L(-1), P <.05). In BLK, the exercise-induced increase in plasma glucose was abolished (0 minutes: 5.7 +/- 0.3; 20 minutes: 5.7 +/- 0.1 mmol. L(-1)). Glucose kinetics were measured using a primed, continuous infusion of [6,6-(2)H] glucose. Glucose production was not different between trials; on average these values were 25.3 +/- 3.9 and 30.9 +/- 4.4 micromol. kg(-1). min(-1) in CON and BLK, respectively. Glucose uptake during exercise was greater (P <.05) in BLK (30.6 +/- 4.6 micromol. kg(-1). min(-1)) compared with CON (18.4 +/- 2.5 micromol. kg(-1). min(-1)). In BLK, plasma insulin and catecholamines were higher (P <.05), while plasma glucagon was unchanged from CON. Free fatty acids (FFA) and glycerol were lower (P <.05) in BLK. These findings demonstrate that adrenergic blockade during intense exercise results in a blunted plasma glucose response that is due to enhanced glucose uptake, with no significant change in glucose production.
本研究考察了α和β肾上腺素能联合阻断对剧烈运动期间葡萄糖动力学的影响。六名耐力训练的男性在摄入安慰剂（CON）或α（盐酸哌唑嗪）和β（马来酸噻吗洛尔）肾上腺素能受体拮抗剂联合用药（BLK）后，以约78%的峰值耗氧量（Vo₂）进行20分钟运动。运动期间CON组血浆葡萄糖升高（0分钟：5.5±0.1；20分钟：6.5±0.3 mmol·L⁻¹，P<.05）。在BLK组，运动诱导的血浆葡萄糖升高被消除（0分钟：5.7±0.3；20分钟：5.7±0.1 mmol·L⁻¹）。使用[6,6-(²)H]葡萄糖的单次静脉注射、持续输注来测量葡萄糖动力学。各试验间葡萄糖生成无差异；CON组和BLK组这些值的平均值分别为25.3±3.9和30.9±4.4 μmol·kg⁻¹·min⁻¹。与CON组（18.4±2.5 μmol·kg⁻¹·min⁻¹）相比，BLK组运动期间的葡萄糖摄取更高（P<.05）（30.6±4.6 μmol·kg⁻¹·min⁻¹）。在BLK组，血浆胰岛素和儿茶酚胺更高（P<.05），而血浆胰高血糖素与CON组相比无变化。BLK组游离脂肪酸（FFA）和甘油更低（P<.05）。这些发现表明，剧烈运动期间肾上腺素能阻断导致血浆葡萄糖反应减弱，这是由于葡萄糖摄取增强，而葡萄糖生成无显著变化。
