Department of Medicine, University of Louisville, Louisville, Kentucky, 40292, USA.
Robley Rex VA Medical Center, Louisville, Kentucky, 40206, USA.
Physiol Rep. 2022 Mar;10(6):e15069. doi: 10.14814/phy2.15069.
Pulmonary mechanosensory receptors provide important inputs to the respiratory center for control of breathing. However, what is known about their structure-function relationship is still limited. In these studies, we explored this relationship comparing bronchopulmonary slowly adapting receptor (SAR) units in rabbits and rats. In morphological studies, sensory units in tracheobronchial smooth muscle labeled with anti-Na /K -ATPase (α3 subunit) were found to be larger in the rabbit. Since larger structures may result from increased receptor size or more numerous receptors, further examination showed receptor size was the same in both species, but more receptors in a structure in rabbits than rats, accounting for their larger structure. In functional studies, SAR units were recorded electrically in anesthetized, open-chest, and artificially ventilated animals and responses to lung inflation were compared at three different constant airway pressures (10, 20, and 30 cmH O). At each level of the inflation, SAR discharge frequencies were found to be higher in rabbits than rats. We conclude that a relatively larger number of receptors in a sensory unit may be responsible for higher SAR activities in rabbit SAR units.
肺机械感受器为呼吸中枢提供重要的呼吸控制输入。然而，关于它们的结构-功能关系的了解仍然有限。在这些研究中，我们通过比较兔和大鼠的支气管肺慢适应感受器（SAR）单位来探索这种关系。在形态学研究中，用抗 Na+/K+-ATPase（α3 亚基）标记的气管支气管平滑肌中的感觉单位在兔中更大。由于较大的结构可能是由于受体大小增加或受体数量增加所致，进一步的检查表明，两种物种的受体大小相同，但兔中的结构中有更多的受体，这解释了它们更大的结构。在功能研究中，在麻醉、开胸和人工通气的动物中用电记录 SAR 单位，并在三个不同的恒定气道压力（10、20 和 30 cmH2O）下比较肺充气的反应。在充气的每个水平，发现兔的 SAR 放电频率高于大鼠。我们得出结论，感觉单位中相对较多的受体可能是兔 SAR 单位中 SAR 活性较高的原因。
