CONTROL OF BREATHING DURING PHYSIOLOGIC CONDITIONS

我们的主要目标是加强对控制 呼吸。一个相关的目标是深入了解 测定运动过程中氧气的运输。第一个具体目标是 确定来自运动肢体的传入信号是否对 锻炼呼吸亢进。在麻醉下的先导研究中，呼吸机 电刺激运动引起的(V-E)反应被损毁减弱 脊髓背外侧沟(DLS)和背外侧索(DLF) L2水平上的路径。除了4条狗中的第1条和2条狗中的第1条 小马，扭伤并没有影响到行走。因此，在 将对8匹清醒的小马进行跑步机运动、V-E和血气研究 DLS、DLF损毁或假手术前、后2~4周。第二个目标 目的是确定颈动脉体失神经(CBD)中的脊髓损害， 门神经失神经(HND)，CBD+HND影响运动 呼吸过多不同于单纯的脊椎病变。前后研究 多处损伤是检验假设的一种手段 机制能够调节运动性呼吸亢进，因此 除非大多数或所有的机制是 被淘汰了。第三个目标是测试呼吸周期的假设 在高海拔地区是由于颈动脉化学感受器增益增加所致 低氧联合低碳酸血症诱导的呼吸暂停阈值。呼吸， 对8匹马在CBD或CBD前后进行血气和脑电监测。 在海平面和3天的清醒和睡眠状态下的假CBD 低血氧饱和度(PaO2=40毫米汞柱)。第四个目标是确定上级 呼吸道、肺或颈动脉感觉机制改变呼吸神经输出 当吸气肌肉长度改变为 长度-张力曲线的不利部分。V-E、血气和 呼吸肌肌电将在正常、CBD、HND和 正压呼吸前和正压呼吸时气管切开的小马(+10 cm 水)，增加肺体积和改变肌肉长度。第五个目标是 确定25%的心率和心输出量是否超调 小马在工作的第一分钟是由于脾的活动 红细胞或外周传入信息。因此，这些响应将 在DLS和DLF脊柱损伤前后以及在其他小马身上进行研究 脾切除前后。小马是一种被证明是慢性疾病的模型 需要维持生理条件的研究。相应地，使用 为理论模型提供了独特的测试 假说是在麻醉条件下使用其他物种得出的。

Our major objective is to enhance understanding of the control of breathing. A related objective is to gain insight into mechanisms which determine O2 transport during exercise. The 1st specific aim is to determine whether afferents from exercising limbs are critical to the exercise hyperpnea. In pilot studies under anesthesia, the ventilatory (V-E) response to electrically induced exercise was attenuated by lesioning the dorsal lateral sulcus (DLS) & dorsal lateral funiculus (DLF) spinal pathways at the L2 level. Except for the 1st of 4 dogs & the 1st of 2 ponies, lesioning did not compromise ambulation. Accordingly, during treadmill exercise, V-E and blood gases will be studied in 8 awake ponies before and 2-4 weeks after DLS and DLF lesions or sham surgery. A 2nd aim is to determine whether spinal lesioning in carotid body denervated (CBD), hilar nerve denervated (HND), and CBD+HND ponies affects the exercise hyperpnea differently than spinal lesions alone. Studies before and after multiple lesions are a means of testing the hypothesis that multiple mechanisms are capable of mediating the exercise hyperpnea, and therefore the hyperpnea may not be attenuated unless most or all mechanisms are eliminated. A 3rd aim is to test the hypothesis that breathing periodicity at high altitude is due to the increased carotid chemoreceptor gain due to hypoxia combined with the hypocapnia-induced apnea threshold. Breathing, blood gases, and EEG will be monitored in 8 ponies before and after CBD or sham CBD in awake and sleeping states at sea level and during 3 days of hypobaria (PaO2 = 40 mmHg). A 4th aim is to determine whether upper airway, lung, or carotid sensory mechanisms alter respiratory neural output to defend tidal volume when inspiratory muscle length is altered to an unfavorable portion of the length-tension curve. V-E, blood gases, and respiratory muscle EMG will be studied in normal, CBD, HND, and tracheostomized ponies before and during positive pressure breathing (+10CM H2O) which increases lung volume and alters muscle length. A 5th aim is to determine whether the 25% overshoots in heart rate and cardiac output of ponies in the 1st min of work are due to mobilization of splenic erythrocytes or peripheral afferent information. These responses will thus be studied before and after DLS and DLF spinal lesions and in other ponies before and after splenectomy. The pony is a proven model for chronic studies requiring maintenance of physiologic conditions. Accordingly, use of the awake pony provides unique tests of theoretical models and hypotheses developed using other species under conditions of anesthesia.