A COMPARISON OF PERIPHERAL AND RUBROSPINAL SYNAPTIC INPUT TO SLOW AND FAST TWITCH MOTOR UNITS OF TRECEPS SURAE
A COMPARISON OF PERIPHERAL AND RUBROSPINAL SYNAPTIC INPUT TO SLOW AND FAST TWITCH MOTOR UNITS OF TRECEPS SURAE
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DOI：
10.1113/jphysiol.1970.sp009090
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发表时间：
1970-01-01
影响因子：
5.5
通讯作者：
BRUGGENC.GT
中科院分区：
文献类型：
--
作者：
BURKE, RE;JANKOWSKA, E;BRUGGENC.GT
1.比较了电刺激不同输入系统在支配小腿三头肌慢肌和快肌单位的运动神经元中诱发的突触后电位，并测定了其收缩速度.刺激屈肌和伸肌神经的高阈值传入和关节传入，在快、慢颤肌运动单位中均诱发以超极化为主的多突触PSPs. Volleys在腓肠神经和隐神经的皮肤传入引起的多突触PSP组成的混合物的抑制性和兴奋性成分。慢缩运动单位的抑制成分占优势，而快缩运动单位则有兴奋成分占优势的趋势.重复刺激红核引起的主要是抑制性的PSP在慢颤单位和混合或主要是兴奋性的PSP在快颤单位。在研究了皮肤和红核脊髓起源的PSP的运动神经元中，这两种类型的PSP之间的兴奋/抑制平衡存在相关性。Ia组双突触抑制性PSPs的振幅与运动单位的抽搐类型有关：慢抽搐单位的IPSPs大于快抽搐单位的IPSPs。红核脊髓条件性齐射被发现促进Ia组IPSPs在快和慢抽搐运动单位。结果表明，在一个给定的运动单位池内，运动神经元的突触输入组织可能有几种基本模式。除了突触分布的数量变化，有证据表明，在从皮肤传入和红核脊髓系统到小腿三头肌运动神经元的传递输入的途径中，也存在兴奋性与抑制性平衡的质的差异。这些质的差异与运动单位抽搐类型相关。
1. Post‐synaptic potentials (PSPs) evoked by electrical stimulation of a variety of input systems have been compared in triceps surae motoneurones innervating slow and fast muscle units, the speed of contraction of which was also determined.2. Stimulation of high threshold afferents in both flexor and extensor muscle nerves, and of joint afferents, evoked polysynaptic PSPs which were predominantly hyperpolarizing in both fast and slow twitch motor units.3. Volleys in cutaneous afferents in the sural and saphenous nerves evoked polysynaptic PSPs composed of mixtures of inhibitory and excitatory components. The inhibitory components were predominant in slow twitch motor units, while in fast twitch units there was a trend towards excitatory predominance.4. Repetitive stimulation of the red nucleus caused predominantly inhibitory PSPs in slow twitch units and mixed or predominantly excitatory PSPs in fast twitch units. There was a correlation in the excitatory/inhibitory balance between PSPs of cutaneous and rubrospinal origin in those motoneurones in which both types of PSPs were studied.5. The amplitudes of group Ia disynaptic inhibitory PSPs were found to be correlated with motor unit twitch type: IPSPs in slow twitch units were larger than those in fast twitch units. Rubrospinal conditioning volleys were found to facilitate group Ia IPSPs in both fast and slow twitch motor units.6. The results suggest that there may be several basic patterns of synaptic input organization to motoneurones within a given motor unit pool. In addition to quantitative variation in synaptic distribution, there is evidence that qualitative differences in excitatory to inhibitory balance also exist in the pathways conveying input from cutaneous afferents and rubrospinal systems to triceps surae motoneurones. These qualitative differences are correlated with the motor unit twitch type.