METABOLITE EFFECTS OF GROUP III AND IV MUSCLE AFFERENTS

拟议中的实验有两个目标。第一个目标是确定 对静息激活的III、IV组传入的刺激 肌肉收缩是供血的中枢神经系统的信号 而工作肌肉中的需求没有得到适当的匹配。这些传入神经 将通过显示它们对和缺血静态反应更多来确定 收缩，而不是自由灌流的收缩，即使这两种类型 收缩而不是缺血的静态收缩比自由收缩 灌流性收缩，即使这两种类型的收缩都会发展成 同样的紧张。需要检验的假设是，乳酸输注和 低氧血症刺激第三组和第四组感觉到不匹配的传入 工作肌肉中的血液供应和需求，但对 感觉不到这种不匹配的传入放电。第二个假设是 被测试二氯乙酸酯，它通过以下方式减弱乳酸的产生 骨骼肌，降低传入神经收缩的反应 感觉到了这种不匹配。这些实验将在 未麻醉的去大脑猫科动物。由以下因素引起的传入冲动 从背根记录小腿三头肌。这个 第二个目标是在脱皮未麻醉的猫身上证明这一组 III和IV后肢肌肉传入是由真动力刺激的 运动“，由丘脑下部运动区的激活引起。 已知刺激这一区域会导致阿尔法的放电模式。 运动神经元与动态运动诱发的运动神经元相同。这个 动脉供血阻断所致脑缺血的影响 工作肌肉，对传入者对动态运动的反应 检查过了。此外，输注乳酸对小鼠心脏功能的影响 将检查传入者对动态运动的反应。假说 有待检验的是，真正的动力运动刺激了III组的传入 通过机械手段和IV组传入受到运动刺激， 这些实验可能会为这个令人困惑的问题提供新的线索 引起这些传入信号的代谢刺激的性质 收缩肌肉的血液供应和需求的中枢神经系统 是不匹配的

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