Muscle reflex stimulates sympathetic postganglionic efferents innervating triceps surae muscles of cats
Muscle reflex stimulates sympathetic postganglionic efferents innervating triceps surae muscles of cats
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DOI：
10.1152/ajpheart.1996.271.1.h38
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发表时间：
1996-07-01
影响因子：
4.8
通讯作者：
Kaufman, MP
中科院分区：
文献类型：
--
作者：
Hill, JM;Adreani, CM;Kaufman, MP
两种神经机制有助于心血管对运动的反应。第一种是中央指令，提出了控制心血管功能的中央运动回路和脑干回路的并行激活。第二，肌肉反射，提出收缩激活的III和IV组传入增加心血管功能。在人类中，交感放电的整个神经记录表明，中央指令增加了交感神经向皮肤的流出，而不是向骨骼肌的流出，肌肉反射增加了交感神经向骨骼肌的流出，而不是向皮肤的流出。因此，我们测试了肌肉反射，而不是中央命令，增加单个交感神经节后传出神经的放电，这些神经支配着未麻醉的猫的三头肌。中脑运动区电刺激可诱发中央指令。这种反射是由电刺激胫神经引起的，而电刺激胫神经又收缩了肱三头肌。六甲溴铵消除自发和诱发活动，证实记录来自交感神经节后纤维。静态收缩使13个传出神经的放电增加（从0.6 +/- 0.2到1.0 +/- 0.3 imp/s, P < 0.05），而中央指令没有使13个传出神经的放电增加（从0.6 +/- 0.2到0.8 +/- 0.2 imp/s, P < 0.05）。然而，在a-肾上腺素能阻断前中央指令未增加9个传出神经的放电（从0.5 +/- 0.2到0.9 +/- 0.4 imp/s, P < 0.05），阻断后则增加（从1.3 +/- 0.2到3.2 +/- 0.8 imp/s, P < 0.05）。我们的结论是，肌肉反射刺激支配骨骼肌血管的交感神经节后传出神经。此外，压力感受器似乎可以缓冲由中央指令引起的这些传入信号的增加。
Two neural mechanisms contribute to the cardiovascular responses to exercise. The first, central command, proposes a parallel activation of central locomotor and brain stem circuits controlling cardiovascular function. The second, the muscle reflex, proposes that contraction-activated group III and IV afferents increase cardiovascular function. In humans, whole nerve recordings of sympathetic discharge suggest that central command increases sympathetic outflow to skin but not to skeletal muscle and that the muscle reflex increases sympathetic outflow to skeletal muscle but not to skin. We therefore tested the hypothesis that the muscle reflex, but not central command, increases the discharge of single sympathetic postganglionic efferents innervating the triceps surae muscles of decerebrate unanesthetized cats. Central command was evoked by electrical stimulation of the mesencephalic locomotor region. The reflex was evoked by electrical stimulation of the tibial nerve, which in turn contracted the triceps surae muscles. Hexamethonium abolished spontaneous and evoked activity, verifying that the recordings were from sympathetic postganglionic fibers. The discharge of 13 efferents was increased by static contraction (from 0.6 +/- 0.2 to 1.0 +/- 0.3 imp/s; P < 0.05) but was not increased by central command (from 0.6 +/- 0.2 to 0.8 +/- 0.2 imp/s; P > 0.05). Nevertheless, the discharge of nine efferents, not increased by central command before a-adrenergic blockade (from 0.5 +/- 0.2 to 0.9 +/- 0.4 imp/s; P > 0.05), was increased after blockade (from 1.3 +/- 0.2 to 3.2 +/- 0.8 imp/s; P < 0.05). We conclude that the muscle reflex stimulates sympathetic postganglionic efferents innervating the vasculature of skeletal muscle. Furthermore, baroreceptors appear to buffer the central command-induced increases in the discharge of these efferents.