EFFECT OF METABOLITES ON GROUP III AND IV AFFERENTS

代谢物对 III 组和 IV 组传入神经的影响

基本信息

批准号：
3341747
负责人：
Marc Peter Kaufman
金额：
$ 9.02万
依托单位：
UNIVERSITY OF CALIFORNIA AT DAVIS
依托单位国家：
美国
项目类别：
财政年份：
1987
资助国家：
美国
起止时间：
1987-07-01 至 1991-06-30
项目状态：
已结题

项目摘要

The proposed experiments have two goals. The first is to identify the stimulus to the group III and IV afferents whose activation by muscular contraction signals the central nervous system that blood supply and demand in a working muscle are not properly matched. These afferents will be identified by showing that they respond more to an ischemic static contraction than to a normal contraction, even though both types of contraction develop the same tension. Once identified, the effect on the discharge of these afferents of arterial injections of several ischemic metabolites, such as adenosine, lactate, phosphate and possibly ammonia will be examined. Likewise, the effect on the discharge of these afferents of hypoxemia, acidemia and hypercarbemia will be examined. These experiments will be performed in unanesthetized decerebrate cats. Afferent impulse activity arising from the triceps surae muscles will be recorded from the dorsal roots. The second goal is to demonstrate in decorticate unanesthetized cats that group III and IV hindlimb muscle afferents are stimulated by a "true dynamic exercise", induced by activation of subthalamic and mesencephalic locomotor centers. Stimulation of these centers is known to cause a discharge pattern in alpha motoneurons that is identical to that evoked by dynamic exercise. The effect of ischemia, induced by occlusion of the arterial blood supply to the working muscle, on the afferents' response to dynamic excercise will be examined. In addition, the effect of infusing ischemic metabolites on the afferents' discharge will be examined. In addition to showing that group III and IV muscle afferents are stimulated by exercise, these experiments may shed new light on the puzzling question as to the nature of the metabolic stimulus causing these afferents to signal the central nervous system that blood supply and demand in a contracting muscle are mismatched.

拟议的实验有两个目标。首先是确定刺激III和IV组的传入，它们的肌肉激活收缩信号表明血液供应和需求的中枢神经系统在工作肌肉中，不正确匹配。这些传入将是通过证明它们对缺血性静态的反应更多收缩而不是正常收缩，即使两种类型收缩会产生相同的张力。一旦确定，对排放这些动脉注射的传入几种缺血性的传入代谢物，例如腺苷，乳酸，磷酸盐和可能的氨将被检查。同样，对这些传入的排放的影响将检查低氧血症，酸血症和高热量。这些实验将在未经麻醉的杂交猫中进行。传入将记录由三头肌引起的冲动活动从背根。第二个目标是在脱脱口角中证明 III和IV Hindlimb肌肉传入的一体式猫是由“真正的动态练习”刺激，激活丘脑和脑脑运动中心。刺激这些已知中心在α运动神经元中引起放电模式与动态锻炼引起的相同。缺血的作用，通过闭塞动脉血液供应向工作肌肉诱导，将检查传入者对动态练习的反应。在此外，注入缺血代谢物对传入的影响将检查排放。除了显示该组III和IV组肌肉传入是通过运动刺激的，这些实验可能会脱落新的关于代谢刺激的性质的令人困惑的问题导致这些传入者发出信号中枢神经系统的信号收缩肌肉的供求不匹配。