Kizakevich P N, McCartney M L, Hazucha M J, Sleet L H, Jochem W J, Hackney A C, Bolick K
Human Studies Facility, Research Triangle Institute, Research Triangle Park, NC 27709, USA.
Eur J Appl Physiol. 2000 Sep;83(1):7-16. doi: 10.1007/s004210000256.
Very little is known about the cardiovascular responses of exercising individuals when exposed to carbon monoxide (CO). Sixteen healthy nonsmoking men aged 18-29 years participated in the study. Using a combination of exposures to CO by breathing from a bag or in an environmental chamber, subjects performed a randomized sequence of brief (5 min) multi-level treadmill and hand-crank exercises on different days at less than 2% carboxyhemoglobin (COHb) and after attaining target levels of 5%, 10%, 15%, and 20% COHb. To assess cardiac function changes we employed noninvasive impedance cardiography (ICG) and three-lead electrocardiograms (ECG). The ICG was used to estimate cardiac output, stroke volume, heart rate, cardiac contractility, and time-to-peak ejection time. The ECG was used to assess myocardial irritability and ischemia, and changes in cardiac rhythm. The results showed that the cardiovascular system compensated for the reduced O2-carrying capacity of the blood by augmenting heart rate, cardiac contractility, and cardiac output for both upper-body and lower-body exercise. While this mechanism served well in submaximal exercise, the enhanced cardiovascular response to exercise was not without physiological costs because it began to fail at moderate levels of CO exposure and exercise. We concluded that young, apparently healthy men can perform submaximal upper and lower-body exercise without overt impairment of cardiovascular function after CO exposures attaining 20% COHb.
对于运动中的个体暴露于一氧化碳（CO）时的心血管反应，我们了解甚少。16名年龄在18至29岁之间的健康非吸烟男性参与了这项研究。通过从袋子中呼吸或在环境舱中吸入CO的组合方式，受试者在不同日期进行了随机顺序的简短（5分钟）多级跑步机和手摇曲柄运动，运动时羧基血红蛋白（COHb）水平低于2%，以及在达到5%、10%、15%和20%的目标COHb水平后。为了评估心脏功能变化，我们采用了无创阻抗心动图（ICG）和三导联心电图（ECG）。ICG用于估计心输出量、每搏输出量、心率、心脏收缩力和射血峰值时间。ECG用于评估心肌应激性和缺血情况以及心律变化。结果表明，心血管系统通过增加心率、心脏收缩力和心输出量来补偿血液中氧气携带能力的降低，无论是上身运动还是下身运动。虽然这种机制在次最大运动中效果良好，但运动时增强的心血管反应并非没有生理代价，因为在中等程度的CO暴露和运动水平时它开始失效。我们得出结论，年轻、看似健康的男性在CO暴露达到20% COHb后，可以进行次最大的上身和下身运动，而不会明显损害心血管功能。
