Douse M A, Powell F L, Milsom W K, Mitchell G S
Department of Comparative Biosciences, University of Wisconsin, Madison 53706.
Respir Physiol. 1989 Dec;78(3):331-43. doi: 10.1016/0034-5687(89)90108-4.
The effects of body temperature (Tb) on pulmonary stretch receptor (PSR) and CO2-sensitive intrapulmonary chemoreceptor (IPC) response characteristics may have important effects on ventilatory control in reptiles. In this study, three questions were addressed: (1) what are the effects of Tb on PSR and IPC responses to airway pressure (Paw) and lung CO2 (PCO2); (2) what are the effects of acute (less than 12 h) vs chronic (greater than 1 week) changes in Tb on both receptor groups; and (3) can predicted changes in the fractional dissociation of imidazole (alpha im), calculated via independent changes in Tb and PCO2, explain the CO2-sensitivity of either IPC or PSR? Single fiber PSR and IPC responses to Paw, PCO2 and Tb were determined in 11 anesthetized Alligator mississippiensis (pentobarbital; 30 mg/kg), acclimated at 20 degrees C (N = 5) or at 30 degrees C (N = 6). PSR activity increased as Paw increased at both Tb, but PSR activity and sensitivity to Paw were lower at 20 degrees C. The average Q10 was 2.1. Increasing inhaled CO2 from 1 to 7% decreased PSR activity by 27 +/- 6% at 20 degrees C and 18 +/- 5% at 30 degrees C. IPC activity decreased as PCO2 increased at both Tb, but IPC activity and sensitivity were reduced at 20 degrees C. The average Q10 was 3.2. Increasing Paw from 2 to 10 cm H2O had inconsistent effects on IPC activity. There were no differences between the effects of acute or chronic changes in Tb on either PSR or IPC responses. Predicted changes in alpha im could not explain the CO2-sensitivity of either IPC or PSR. We conclude that PSR and IPC adapt rapidly to Tb changes. The larger Q10 of IPC suggests that the relative role of IPC vs PSR in ventilatory control may be greater at elevated body temperatures.
体温（Tb）对肺牵张感受器（PSR）和二氧化碳敏感的肺内化学感受器（IPC）反应特性的影响，可能对爬行动物的通气控制具有重要作用。在本研究中，探讨了三个问题：（1）Tb对PSR和IPC对气道压力（Paw）和肺二氧化碳（PCO2）反应的影响是什么；（2）Tb的急性（小于12小时）与慢性（大于1周）变化对这两种感受器的影响是什么；（3）通过Tb和PCO2的独立变化计算出的咪唑分数解离（αim）的预测变化，能否解释IPC或PSR的二氧化碳敏感性？在11只麻醉的密西西比短吻鳄（戊巴比妥；30mg/kg）中测定了单纤维PSR和IPC对Paw、PCO2和Tb的反应，这些短吻鳄在20℃（N = 5）或30℃（N = 6）下适应环境。在两个Tb水平下，PSR活动均随Paw升高而增加，但在20℃时，PSR活动和对Paw的敏感性较低。平均Q10为2.1。在20℃时，将吸入二氧化碳从1%增加到7%，PSR活动降低27±6%，在30℃时降低18±5%。在两个Tb水平下，IPC活动均随PCO2升高而降低，但在20℃时，IPC活动和敏感性降低。平均Q10为3.2。将Paw从2cmH2O增加到10cmH2O对IPC活动的影响不一致。Tb的急性或慢性变化对PSR或IPC反应的影响没有差异。αim的预测变化不能解释IPC或PSR的二氧化碳敏感性。我们得出结论，PSR和IPC能迅速适应Tb变化。IPC较大的Q10表明，在体温升高时，IPC相对于PSR在通气控制中的相对作用可能更大。
