Millhorn D E, Kiley J P
Respir Physiol. 1984 Oct;58(1):51-64. doi: 10.1016/0034-5687(84)90044-6.
The present study was undertaken to determine if the phrenic responses to vagally mediated inputs are also affected by focal cooling of the intermediate areas (IA) of the ventral medulla. Anesthetized, paralyzed cats whose vagi and carotid sinus nerves had been cut were studied. The IA were cooled focally with a thermostatically controlled thermode. When the IA were 40 degrees C, low intensity vagal stimulation caused inhibition of phrenic activity. The stimulus was also applied when IA were cooled to 30 and 20 degrees C. The magnitude of the inhibition was unaffected by the cooling. In another series of experiments, high intensity vagal stimulation was used. This led to an hyperpnea when IA were 40 degrees C. The magnitude of the response was much smaller when the test stimulus was given at lower IA temperatures. The effect of cooling IA on the phrenic response to mechanical stimulation of pulmonary stretch receptors and airway irritant receptors were also studied in cats with intact vagi. We found that the response to irritant receptor, but not to stretch receptor, stimulation was abolished by the cooling. We conclude that the intermediate areas are involved in the integration of afferent input from airway irritant receptors that reaches the respiratory controller via high threshold vagal afferents, but not involved in processing signals from pulmonary stretch receptors.
本研究旨在确定延髓腹侧中间区域（IA）的局部冷却是否也会影响膈神经对迷走神经介导输入的反应。对麻醉、麻痹且切断迷走神经和颈动脉窦神经的猫进行了研究。使用恒温控制的热电极对IA进行局部冷却。当IA温度为40℃时，低强度迷走神经刺激会抑制膈神经活动。当IA冷却至30℃和20℃时也施加刺激。冷却并未影响抑制的程度。在另一系列实验中，使用了高强度迷走神经刺激。当IA温度为40℃时，这会导致呼吸增强。当在较低的IA温度下给予测试刺激时，反应的程度要小得多。还在迷走神经完整的猫中研究了冷却IA对膈神经对肺牵张感受器和气道刺激感受器机械刺激反应的影响。我们发现，冷却消除了对刺激感受器的反应，但对牵张感受器的刺激反应未消除。我们得出结论，中间区域参与了通过高阈值迷走神经传入纤维到达呼吸控制中枢的气道刺激感受器传入输入的整合，但不参与处理来自肺牵张感受器的信号。
