Shannon R, Bolser D C, Lindsey B G
Department of Physiology and Biophysics, College of Medicine, University of South Florida, Tampa 33612.
J Appl Physiol (1985). 1988 Dec;65(6):2498-505. doi: 10.1152/jappl.1988.65.6.2498.
Studies were conducted to test the hypothesis that nonrespiratory-modulated units are last-order interneurons mediating the effects of intercostal muscle tendon organs on medullary inspiratory neuron activity. Vagotomized, anesthetized, or decerebrate cats were used. Results show the following. 1) Afferents from different receptor types (i.e., intercostal tendon organs and chest wall cutaneous receptors) that inhibit medullary inspiratory neuron activities evoke the same units. 2) Gastrocnemius muscle group I afferent fibers evoke some of the same units as intercostal afferents but do not alter respiratory activity. 3) The "pneumotaxic center" and laryngeal nerve afferents, which inhibit medullary inspiratory activity, evoke different medullary units than intercostal afferents. 4) Evoked units are not active in spontaneously breathing cats. Additional results suggest that a few respiratory neurons near the retrofacial nucleus may be involved in the mediation of the inspiratory inhibitory effects of intercostal tendon organs. These results do not establish the mechanism by which intercostal muscle tendon organs reduces medullary inspiratory activity.
非呼吸调制单元是终末中间神经元，介导肋间肌腱器官对延髓吸气神经元活动的影响。实验使用了迷走神经切断、麻醉或去大脑的猫。结果如下：1）来自不同受体类型（即肋间肌腱器官和胸壁皮肤感受器）的抑制延髓吸气神经元活动的传入神经激活相同的单元。2）腓肠肌Ⅰ类传入纤维激活的一些单元与肋间传入纤维相同，但不改变呼吸活动。3）抑制延髓吸气活动的“呼吸调整中枢”和喉神经传入纤维激活的延髓单元与肋间传入纤维不同。4）在自主呼吸的猫中，诱发的单元不活跃。其他结果表明，面神经后核附近的一些呼吸神经元可能参与介导肋间肌腱器官的吸气抑制作用。这些结果并未确定肋间肌腱器官降低延髓吸气活动的机制。
