Lockette W, McCurdy R, Smith S, Carretero O
Med Sci Sports Exerc. 1987 Feb;19(1):7-10.
Trained endurance athletes have a smaller rise in blood pressure, heart rate, and catecholamine response to stress when compared to an untrained, control population. Since pre-synaptic alpha 2-adrenergic receptors modulate the control of epinephrine release from nerve terminals, and since platelets are used as models of monoaminergic neurons, we investigated changes in the number and affinity binding of alpha 2-adrenergic receptors on platelets from endurance athletes and a sedentary population using the radiolabeled ligand yohimbine. We found, compared to a control, sedentary population, trained athletes had a 45% increase in the number of platelet alpha 2-adrenergic receptors (338 +/- 39 receptors/platelet vs 233 +/- 25 receptors/platelet, P less than 0.05) with no change in the dissociation constant (2.53 nM +/- 0.2 vs 2.24 nM +/- 0.2, NS) or the ED50 concentration for the competitive displacement of 2.5 nM yohimbine by epinephrine (2.8 X 10(-6) M vs 3.34 X 10(-6) M, NS). The increase in alpha 2-adrenergic receptors found in athletes may explain their decreased catecholamine response and concomitant physiologic responses to exertion.
与未经训练的对照人群相比，经过训练的耐力运动员在面对压力时，血压、心率和儿茶酚胺反应的升高幅度较小。由于突触前α2-肾上腺素能受体调节神经末梢肾上腺素的释放控制，并且血小板被用作单胺能神经元的模型，我们使用放射性标记配体育亨宾研究了耐力运动员和久坐人群血小板上α2-肾上腺素能受体的数量和亲和力结合的变化。我们发现，与对照久坐人群相比，训练有素的运动员血小板α2-肾上腺素能受体数量增加了45%（338±39个受体/血小板对233±25个受体/血小板，P<0.05），解离常数（2.53 nM±0.2对2.24 nM±0.2，无显著性差异）或肾上腺素对2.5 nM育亨宾竞争性置换的ED50浓度（2.8×10-6 M对3.34×10-6 M，无显著性差异）没有变化。运动员中发现的α2-肾上腺素能受体增加可能解释了他们儿茶酚胺反应的降低以及对运动的伴随生理反应。
