Interactions of body temperatures and modulators of human pulmonary ventilation

运动通风控制的潜在机制仍然是人类生理学中的一个反常现象。许多关于这一控制系统功能的假说都不能完全解释剧烈运动时肺通气量相对于代谢需求的不成比例增加。我们假设在运动中，核心温度(TC)对肺通气量有显著影响。支持这一新观点的证据来自我们对被动(即休息时热浸泡)和主动加温(即运动)的人的肺换气的TC阈值的论证，以及在更明显的高热期间TC与肺通气量之间的比例关系。这一比例表明了一种因果关系，这一因果关系得到了我们进一步研究的支持，即TC与已知的肺通气调节因子(如动脉血二氧化碳分压/pH和氧分压)之间存在积极的相互作用。一种新的观点认为，升高的体温刺激了换气，当体温高于化学调节时，紧随其后的是第二阶段或残留的喘息反应。本研究的目的是进一步探讨高温引起的过度换气的本质和机制。为了达到这一目标，我们将评估在热疗过程中，通气性调节剂和体温调节剂如何相互作用，影响体温和化学调节。将采用逐个呼吸的潮气末压力系统，以夹住潮气末二氧化碳和氧气的分压。这项研究的新颖性和意义将有助于解决人类如何以及为什么过度换气这一长期存在的异常现象。阐明通风调节器和温度调节器如何在热调节和化学调节中相互作用，将有助于拓宽对这两个生理控制系统在人类中的功能的理解。

Mechanisms underlying the control of exercise ventilation remain an anomaly in human physiology. Numerous hypotheses on the function of this control system are unable to fully explain the disproportionate increases in pulmonary ventilation relative to metabolic needs during intense exercise. We hypothesized that during exercise core temperature (Tc) is a significant influence on pulmonary ventilation. Evidence supporting this novel view was from our demonstration of Tc thresholds for pulmonary ventilation in both passively (i.e. hot immersion at rest) and actively warmed (i.e. exercise) humans and proportional relationships between Tc and pulmonary ventilation during more pronounced hyperthermia. This proportionality suggested a causal relationship that was supported by our further studies that indicated positive interactions between Tc and known modulators (i.e. arterial PCO2/pH & PO2) of pulmonary ventilation. An emerging view became that elevated Tc stimulates ventilation and this is followed by a second phase or vestigial panting response when thermo- is prioritized over chemo-regulation. The objective of the proposed research is to further explore the nature and mechanisms underlying this hyperthermia-induced hyperventilation. To attain this objective we will assess how modulators of ventilation and Tc interact in their influences on thermo- and chemo- regulation during hyperthermia. A breath-by-breath end-tidal forcing system will be employed to allow clamping of partial pressures of end-tidal carbon dioxide and oxygen. The novelty and significance of this research will be to contribute to the resolution the long-standing anomaly of how and why humans hyperventilate heavy exercise. Elucidating how modulators of ventilation and temperature interact in thermo- and chemo- regulation of will help broaden the understanding of the function of these two physiological control systems in humans.