Barosensory neurons in the ventrolateral medulla in rabbits and their responses to various afferent inputs from peripheral and central sources.
Barosensory neurons in the ventrolateral medulla in rabbits and their responses to various afferent inputs from peripheral and central sources.
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DOI：
10.2170/jjphysiol.36.1141
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
N. Terui;Y. Saeki;M. Kumada
中科院分区：
文献类型：
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作者：
N. Terui;Y. Saeki;M. Kumada
在55只被麻醉和麻痹的成年兔子中，在腹外侧髓质（VLM）内发现了161个自发活动的神经元，这些神经元对主动脉神经a纤维的电刺激有反应。它们被称为压力感觉VLM神经元，因为主动脉神经a纤维被认为完全由来自动脉压力受体的传入神经组成。测试的40%的压力感觉VLM神经元（49/123）被背外侧索刺激反向激活，表明它们发送下行球脊髓投射。刺激主动脉神经a纤维可抑制压力感觉VLM神经元的自发放电。在接受测试的80个神经元中，93%的神经元对主动脉神经c纤维（一种混合了压力感觉和非压力感觉传入神经）的刺激也有反应。对19只迷走神经切除、主动脉神经破坏的家兔，静脉注射苯肾上腺素自然刺激颈动脉窦压力感受器，可抑制所有50个压力感觉VLM神经元的自发活动。相比之下，通过向颈动脉窦内注射NaCN对右侧或左侧颈动脉体化学感受器进行药物刺激，可增强93%的压力感觉VLM神经元的活性（41/44）。神经元对对侧颈动脉窦的化学感受器的刺激反应总是更大。8个压力感觉VLM神经元中有7个（88%）在下丘脑后区刺激下被正视兴奋。在29只迷走神经切除的动物的97个神经元中，有74%的神经元被识别出一种与膈神经活动锁定的独特呼吸相关节律。因此，压力感觉VLM神经元的自发活动受到来自主动脉和颈动脉窦压力感受器的传入输入的抑制，但受到来自颈动脉体化学感受器和下丘脑后区传入信号的激发。它也受到产生呼吸节律的中枢机制的影响。
In 55 anesthetized and paralyzed adult rabbits, 161 spontaneously active neurons which responded to electrical stimulation of A-fibers of the aortic nerve were found within the ventrolateral medulla (VLM). They were termed barosensory VLM neurons, since the aortic nerve A-fibers were considered to consist exclusively of afferents from arterial baroreceptors. Forty percent of barosensory VLM neurons tested (49/123) were activated antidromically by stimulation of the dorsolateral funiculus indicating that they send descending bulbospinal projections. Spontaneous discharges of barosensory VLM neurons were invariably inhibited by stimulation of aortic nerve A-fibers. Ninety-three percent of 80 neurons tested also responded to stimulation of aortic nerve C-fibers, a mixture of barosensory and nonbarosensory afferents. Natural stimulation of carotid sinus baroreceptors by an intravenous injection of phenylephrine in 19 vagotomized rabbits with aortic nerves disrupted inhibited spontaneous activity of all the 50 barosensory VLM neurons tested. By contrast, pharmacological stimulation of right or left carotid body chemoreceptors by close arterial injection of NaCN into the carotid sinus augmented activity of 93% of barosensory VLM neurons tested (41/44). The neuronal response was always greater to stimulation of chemoreceptors in the contralateral carotid sinus. Seven out of 8 barosensory VLM neurons tested (88%) were orthodromically excited by stimulation of the posterior hypothalamic area. In 74% of the 97 neurons examined in 29 vagotomized animals, a distinct respiratory-related rhythm, locked to that of phrenic nerve activity, was discerned. Thus, spontaneous activity of barosensory VLM neurons is inhibited by afferent inputs from aortic and carotid sinus baroreceptors, but is excited by incoming signals from carotid body chemoreceptors and the posterior hypothalamic area. It is also subject to the influence of the central mechanism generating the respiratory rhythm.