The acute ventilatory response to a brief period of hypoxia (AHVR) was measured in six subjects (a) at rest, (b) during electrically induced leg exercise (EEL), (c) during voluntary leg exercise at an external work rate matched to electrical exercise (EV1) and (d) during voluntary leg exercise at an internal work rate (i.e. metabolic rate) matched to electrical exercise (EV2). The end-tidal PO2 during hypoxia was 50 mmHg and the end-tidal PCO2 was held constant at 1-2 mmHg above resting values throughout each of these four protocols. 2. EEL was produced by surface electrode stimulation of the quadriceps muscles so as to cause the legs to extend at the knee and lift a set of weights via a pulley system. During EV1, each subject lifted the same weight through the same height and at the same frequency as during his EEL protocol. During EV2, the weight, the height through which it was lifted and the frequency of voluntary contractions were altered to produce a similar O2 consumption and CO2 production as during EEL. 3. In each subject, end-tidal PCO2 values showed no change between the four protocols, and in three subjects in whom they were measured, arterial PCO2 values were also similar between the protocols. Venous lactate levels did not increase after EEL or EV2. 4. The AHVR during EEL (14.1 +/- 1.42 l min-1; mean +/- S.E.M) was significantly increased (Student's paired t test) compared with rest (7.55 +/- 1.10 l min-1; P < 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)
摘要
在六名受试者中测量了对短时间缺氧的急性通气反应（AHVR）：（a）静息时；（b）电诱发腿部运动（EEL）期间；（c）在与电运动匹配的外部工作率下进行自主腿部运动（EV1）时；（d）在与电运动匹配的内部工作率（即代谢率）下进行自主腿部运动（EV2）时。在缺氧期间，呼气末PO2为50 mmHg，并且在这四个方案的每一个中，呼气末PCO2均保持在比静息值高1 - 2 mmHg的恒定水平。2. 通过表面电极刺激股四头肌产生EEL，以使腿部在膝盖处伸展并通过滑轮系统提起一组重物。在EV1期间，每个受试者提起的重量、通过的高度和频率与他在EEL方案期间相同。在EV2期间，改变重量、提起的高度和自主收缩的频率，以产生与EEL期间相似的耗氧量和二氧化碳产生量。3. 在每个受试者中，四个方案之间呼气末PCO2值没有变化，并且在测量了动脉PCO2值的三名受试者中，各方案之间动脉PCO2值也相似。EEL或EV2后静脉乳酸水平没有增加。4. 与静息时（7.55 +/- 1.10 l min-1；P < 0.003）相比，EEL期间的AHVR（14.1 +/- 1.42 l min-1；平均值 +/- 标准误）显著增加（学生配对t检验）。（摘要截断于250字）
