Dodd S, Powers S, O'Malley N, Brooks E, Sommers H
Applied Physiology Laboratory, Louisiana State University, Baton Rouge 70803.
Aviat Space Environ Med. 1988 Mar;59(3):255-8.
The purpose of these experiments was to determine the effects of acute beta-blockade on the kinetics of oxygen uptake (VO2), expired carbon dioxide (VCO2), and expired ventilation (VE) in the transition from rest to submaximal exercise. Six male subjects exercised for 6 min on a cycle ergometer (60 W) initiated as a square wave from rest on two occasions. The beta-blockade experiment began 60 min after the subject ingested propranolol hydrochloride (1 mg.kg-1 BW) while the second experiment served as control with the treatment order counterbalanced. Ventilation and gas exchange were monitored by open circuit techniques and the data were modeled with a single-component exponential function using a time delay. No differences existed (p greater than 0.05) in the steady state VO2, VCO2, or VE nor the kinetics of VCO2 and VE between treatments. However, the rate of adaptation of VO2 toward steady state was significantly slowed (p less than 0.05) with beta-blockade. These data suggest that acute beta blockade results in diminished VO2 kinetics in the transition from rest to steady-state exercise. We hypothesize that the mechanism to explain this finding is a slowed time course of cardiac output adjustment at the beginning of exercise.
这些实验的目的是确定急性β受体阻滞剂对从静息状态过渡到次最大运动时氧摄取（VO₂）、呼出二氧化碳（VCO₂）和呼出通气量（VE）动力学的影响。六名男性受试者在自行车测力计上以60瓦的功率进行6分钟运动，运动以方波形式从静息状态开始，共进行两次。β受体阻滞剂实验在受试者摄入盐酸普萘洛尔（1毫克·千克体重）60分钟后开始，第二次实验作为对照，治疗顺序相互平衡。通过开路技术监测通气和气体交换，并使用具有时间延迟的单组分指数函数对数据进行建模。两种处理之间的稳态VO₂、VCO₂或VE以及VCO₂和VE的动力学均无差异（p大于0.05）。然而，β受体阻滞剂使VO₂向稳态的适应速率显著减慢（p小于0.05）。这些数据表明，急性β受体阻滞剂导致从静息状态过渡到稳态运动时VO₂动力学减弱。我们假设解释这一发现的机制是运动开始时心输出量调整的时间进程减慢。
