METABOLITE EFFECTS ON GROUP 111 AND IV MUSCLE AFFERENTS

拟议的实验有两个目标。 第一个目标是确定 刺激组III和IV传入，其激活静态 肌肉收缩向中枢神经系统发出信号， 和工作肌肉的需求不匹配。 这些传入神经 将通过显示它们对缺血性静态 收缩比自由灌注收缩，即使这两种类型 缺血性静态收缩比自由收缩 灌注收缩，即使这两种类型的收缩发展， 同样的紧张。 待检验的假设是乳酸输注和 低氧血症刺激III组和IV组传入感受到 血液供应和需求的工作肌肉，但没有影响， 感觉不到这种不匹配的传入神经的放电。 第二个假设是 测试表明，二氯乙酸盐，它减弱乳酸的生产， 骨骼肌，减少对传入神经收缩的反应， 感知这种不匹配。 这些实验将在 未麻醉的去脑猫 传入冲动活动， 从背根记录小腿三头肌。 的 第二个目标是在未麻醉的去皮质猫中证明， III和IV后肢肌肉传入由真正的“真实动力”刺激 运动”，由丘脑底运动区的激活诱导。 已知刺激该区域会引起α放电模式 运动神经元与动态运动诱发的运动神经元相同。 的 缺血的影响，由动脉供血闭塞引起， 工作肌肉，对传入神经对动态运动的反应将是 考察 此外，输注乳酸对 研究传入神经对动态运动的反应。 的假设 真正的动态运动会刺激第三组传入神经 通过机械手段和运动刺激第四组传入神经， 这些实验可能会对这个令人困惑的问题提供新的解释， 代谢刺激的性质导致这些传入信号， 在收缩肌肉中供应和需求血液的中枢神经系统 不匹配

The proposed experiments have two goals. The first goal is to identify the stimulus to the group III and IV afferents whose activation by static 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 and ischemic static contraction than to a freely perfused contraction, even though both types of contraction than to an ischemic static contraction than to a freely perfused contraction, even though both types of contraction develop the same tension. The hypothesis to be tested is that lactic acid infusion and hypoxemia stimulate group III and IV afferents sensing a mismatch between blood supply and demand in the working muscle, but have no effect on the discharge of afferents not sensing this mismatch. The second hypothesis to be tested that dichloracetate, which attenuates lactic acid production by skeletal muscle, decreases the responses to contraction of afferents not sensing this mismatch. 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 true "true dynamic exercise", induced by activation of the subthalamic locomotor region. Stimulation of this region 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 exercise will be examined. In addition, the effect of infusing lactic acid on the afferents' response to dynamic exercise will be examined. The hypothesis to be tested is that true dynamic exercise stimulates group III afferents by mechanical means and group IV 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