Frappell P B, Daniels C B
School of Biological Sciences, Flinders University of South Australia, Adelaide.
Respir Physiol. 1991 Nov;86(2):257-70. doi: 10.1016/0034-5687(91)90085-w.
The effect of temperature upon ventilation and metabolism was measured on a breath by breath basis in the lizard Ctenophorus nuchalis. This species displayed a typical reptilian breathing pattern; groups of breaths separated by periods of breath holding. The lengths of the non-ventilatory periods (NVP) decreased as temperature increased. As a result, overall breathing frequency (f) displayed a thermal dependence. Outside the preferred temperature range (27-37 degrees C) f was also affected by changes in the frequency of breathing that occurred during periods of ventilation (f'). On the other hand, tidal volume (VT) was maintained constant at all temperatures except 42 degrees C ('panting' threshold). Thus, due to the thermal dependency of f, ventilation (VE) displayed a significant increase between 18 and 37 degrees C. Metabolism (VO2 and VCO2) also increased within this temperature range. However, as a result of a lower Q10 for ventilation, ventilatory requirement (VE/VO2 and VE/VCO2) decreased. In addition, lung volume (LV) increased with temperature. Examination of the alveolar ventilation-PCO2 relationship revealed that as a result of the increase in LV the level of intrapulmonary CO2 at the end of an NVP was maintained irrespective of temperature. This implies a temperature-independent chemical threshold for the onset of breathing. It is postulated that with temperature the observed increase in LV could offset the increase in metabolism by slowing the rise of intrapulmonary CO2 levels. This would delay the onset of breathing which in turn would lower VE/VCO2 (and VE/VO2) by preventing an effectual hyperventilation. This supports the notion, at least in C. nuchalis, that relative alkalinity is maintained.
在鬃狮蜥（Ctenophorus nuchalis）身上逐次呼吸测量了温度对通气和代谢的影响。该物种呈现出典型的爬行类呼吸模式；呼吸周期由屏气期分隔。随着温度升高，非通气期（NVP）的时长缩短。因此，总体呼吸频率（f）呈现出温度依赖性。在偏好温度范围（27 - 37摄氏度）之外，f还受到通气期呼吸频率（f'）变化的影响。另一方面，除了42摄氏度（“喘气”阈值）外，潮气量（VT）在所有温度下均保持恒定。因此，由于f的温度依赖性，通气量（VE）在18至37摄氏度之间显著增加。代谢率（VO2和VCO2）在此温度范围内也增加。然而，由于通气的Q10较低，通气需求（VE/VO2和VE/VCO2）降低。此外，肺容积（LV）随温度升高。对肺泡通气 - PCO2关系的研究表明，由于LV增加，无论温度如何，NVP结束时肺内CO2水平得以维持。这意味着呼吸起始存在一个与温度无关的化学阈值。据推测，随着温度升高，观察到的LV增加可能通过减缓肺内CO2水平的上升来抵消代谢增加的影响。这将延迟呼吸起始，进而通过阻止有效的过度通气降低VE/VCO2（以及VE/VO2）。这支持了至少在鬃狮蜥中维持相对碱度的观点。
