Erlichman J S, Leiter J C
Department of Physiology, Dartmouth Medical School, Lebanon, New Hampshire.
Respir Physiol. 1993 Sep;93(3):347-63. doi: 10.1016/0034-5687(93)90080-t.
We have studied the response of the pneumostome to CO2, O2 and combined CO2 and O2 in intact snails. We found that pneumostomal opening increases in response to both hypercapnia and mild hypoxia. We determined which neural structures were essential for the pneumostomal response to CO2 by eliminating parts of the nervous system: the subesophageal ganglia and an intact anal nerve were necessary and sufficient elements for the CO2 response. Within the subesophageal ganglia, we identified a discrete region on the medial margin of the visceral ganglion that was capable of increasing pneumostomal area when focally stimulated with 6% CO2. Ion substitution experiments indicated that pneumostomal responses to hypercapnia were not mediated by the pneumostomal motor neurons themselves, but rather by interneurons connected polysynaptically to the motor neurons controlling pneumostomal function. In conclusion, intact H. aspersa have a ventilatory response to CO2, and this response is mediated by CO2 sensitive cells located in a small area of the central nervous system.
我们研究了完整蜗牛的气门对二氧化碳、氧气以及二氧化碳和氧气组合的反应。我们发现，气门开口会因高碳酸血症和轻度缺氧而增加。我们通过切除部分神经系统来确定哪些神经结构对于气门对二氧化碳的反应至关重要：咽下神经节和完整的肛神经是二氧化碳反应所必需且足够的要素。在咽下神经节内，我们在内脏神经节内侧边缘确定了一个离散区域，当用6%的二氧化碳进行局部刺激时，该区域能够增加气门面积。离子替代实验表明，气门对高碳酸血症的反应不是由气门运动神经元自身介导的，而是由与控制气门功能的运动神经元多突触连接的中间神经元介导的。总之，完整的散大蜗牛对二氧化碳有通气反应，并且这种反应由位于中枢神经系统小区域内的对二氧化碳敏感的细胞介导。
