Hutton R S, Nelson D L
Med Sci Sports Exerc. 1986 Feb;18(1):69-74.
Alterations in Golgi tendon organs' (Ib afferent receptors) stretch sensitivity were assessed in fatigued gastrocnemius muscle of cats. Muscle fatigue to 60-50% peak tension was induced in 13 cats by electrical stimulation of L7 and S1 ventral roots. Forty-three group Ib afferent fibers were recorded in L7 or S1 dorsal root filaments before and during fatigue. Fiber activity was assessed by applying to the Achilles tendon a 5-mm ramp stretch at 5 or 25-30 mm X s-1. Group Ib afferent responses to both velocities of stretch were either completely abolished or depressed over several seconds compared to pre-fatigue firing frequencies. When responding, longer latencies (measured at 5 mm X s-1 only) to firing onset occurred during fatigue. Increasing the rate of stretch (250 mm X s-1) to produce a 5-mm stretch approximately equivalent to twitch tension time revealed a depression more selective to static stretch sensitivity. Post-excitation depression of the Ib receptor potential appears to be one possible mechanism. These acute adaptations in Ib afferent discharge to muscle stretch were opposite in direction to those recently reported in fatigued muscle for group Ia and group II muscle spindle afferents. Functional implications of these results are discussed.
在猫的腓肠肌疲劳状态下，评估了高尔基腱器官（Ib传入感受器）拉伸敏感性的变化。通过电刺激L7和S1腹根，在13只猫中诱发肌肉疲劳至峰值张力的60 - 50%。在疲劳前和疲劳期间，在L7或S1背根细丝中记录了43条Ib类传入纤维。通过以5或25 - 30 mm·s⁻¹的速度对跟腱施加5 mm的斜坡拉伸来评估纤维活性。与疲劳前的放电频率相比，Ib类传入纤维对两种拉伸速度的反应在几秒钟内完全消失或受到抑制。在疲劳期间，当做出反应时，放电起始的潜伏期更长（仅在5 mm·s⁻¹时测量）。将拉伸速度增加到250 mm·s⁻¹以产生约等于抽搐张力时间的5 mm拉伸，显示出对静态拉伸敏感性更具选择性的抑制。Ib受体电位兴奋后的抑制似乎是一种可能的机制。Ib类传入纤维对肌肉拉伸的这些急性适应性变化方向与最近报道的疲劳肌肉中Ia类和II类肌梭传入纤维的变化方向相反。讨论了这些结果的功能意义。
