Li J, Potts J T, Mitchell J H
Moss Heart Center, Dallas, Texas 75235-9034, USA.
Am J Physiol. 1998 Mar;274(3):H901-8. doi: 10.1152/ajpheart.1998.274.3.H901.
A previous study has shown increased Fos-like immunoreactivity (FLI), a marker of neural activation, in the nucleus of the solitary tract (NTS) and the ventrolateral medulla (VLM) after static muscle contraction elicited by electrical stimulation of L7 and S1 ventral roots of the spinal cord in anesthetized, baroreceptor-intact cats. Because the electrically induced static muscle contraction reflexly increased arterial blood pressure, the concomitant activation of the arterial baroreceptor reflex during static muscle contraction may have resulted in some of the FLI labeling that was observed in the medulla. The purpose of this study was to determine regions in the medulla that are activated by muscle contraction in the absence of arterial baroreceptor input. Electrical stimulation of L7 and S1 ventral roots of the spinal cord was used to elicit static muscle contraction, and FLI in the medulla was determined in barointact and barodenervated cats. In barointact contraction cats, FLI was observed in the lateral reticular nucleus (LRN), NTS, lateral tegmental field (FTL), subretrofacial nucleus (SRF), and A1 region of the medulla. In barodenervated contraction cats, FLI increased in the same regions; however, the number of FLI-labeled cells in the NTS, FTL, and A1 region was significantly less than in barointact contraction animals. No significant difference in the number of FLI-labeled cells was found in the LRN and SRF between the two groups. These results clearly demonstrate that cardiovascular regions in the medulla are activated by input from afferent activity originating in skeletal muscle independently of concomitant arterial baroreceptor reflex activation.
先前的一项研究表明，在麻醉的、压力感受器完整的猫中，通过电刺激脊髓L7和S1腹根引发静态肌肉收缩后，孤束核（NTS）和延髓腹外侧区（VLM）中神经激活的标志物——Fos样免疫反应性（FLI）增加。由于电诱导的静态肌肉收缩会反射性地升高动脉血压，因此在静态肌肉收缩过程中伴随的动脉压力感受器反射激活可能导致了在延髓中观察到的一些FLI标记。本研究的目的是确定在没有动脉压力感受器输入的情况下，延髓中被肌肉收缩激活的区域。使用电刺激脊髓L7和S1腹根来引发静态肌肉收缩，并在压力感受器完整和去神经支配的猫中测定延髓中的FLI。在压力感受器完整的收缩猫中，在延髓的外侧网状核（LRN）、NTS、外侧被盖区（FTL）、面神经后核（SRF）和A1区观察到FLI。在去神经支配的收缩猫中，相同区域的FLI增加；然而，NTS、FTL和A1区中FLI标记细胞的数量明显少于压力感受器完整的收缩动物。两组之间LRN和SRF中FLI标记细胞的数量没有显著差异。这些结果清楚地表明，延髓中的心血管区域是由源自骨骼肌的传入活动输入激活的，与伴随的动脉压力感受器反射激活无关。
