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首页> 外文期刊>American Journal of Physiology >Differential frequency-dependent reflex integration of myelinated and nonmyelinated rat aortic baroreceptors.
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Differential frequency-dependent reflex integration of myelinated and nonmyelinated rat aortic baroreceptors.

机译：髓鞘和非髓鞘大鼠主动脉压力感受器的频率依赖性反射积分差异。

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摘要

Electrical activation of myelinated (A type) and nonmyelinated (C type) baroreceptor axons (BR) in aortic depressor nerve (ADN) evoked baroreflex changes in mean arterial pressure (MAP) in chloralose-urethan-anesthetized rats. Low stimulation intensities (<3 V) activated only A-type BR electroneurograms (ENG). A-type selective stimulus trains required minimum frequencies >10 Hz to evoke reflex MAP decreases, and the largest MAP responses occurred at 50 Hz and higher. In contrast, high stimulation intensities (18-20 V) maximally activated two volleys in ADN ENG corresponding to A- and C-type BR volleys. High-intensity trains decreased MAP at low frequency (1 Hz) and largest reflex responses at >/=5 Hz. Capsaicin (Cap) applied periaxonally to ADN selectively blocked C-type ENG volleys but not A-type volleys. Reflex curves with supramaximal intensity during Cap were indistinguishable from the pre-Cap, low-intensity baroreflexes. In comparison, vagus ENG showed graded Cap block of the C-fiber volley (ED50 = 200 nM) without significant attenuation of the A-type volley below 1 microM. However, 100 microM Cap blocked conduction in all myelinated vagal axons as well as C-type axons. Thus Cap is selective for sensory C-type axons only at low micromolar concentrations. Myelinated and nonmyelinated arterial BR evoke characteristically different frequency-response reflex relations that suggest distinct differences in sensory information processing mechanisms.
机译：主动脉降压神经（ADN）中髓鞘（A型）和非髓鞘（C型）压力感受器轴突（BR）的电激活引起氯醛-尿烷麻醉的大鼠平均动脉压（MAP）的压力反射变化。低刺激强度（<3 V）仅激活A型BR电子神经图（ENG）。 A型选择性刺激训练要求最小频率> 10 Hz，以引起反射MAP降低，最大MAP响应发生在50 Hz或更高的频率。相反，高刺激强度（18-20 V）可以最大程度地激活ADN ENG中与A和C型BR齐射相对应的两个齐射。高强度训练降低了低频（1 Hz）时的MAP，并且在> / = 5 Hz时具有最大的反射响应。将辣椒素（Capsaicin，Cap）以轴突方式施用到ADN上，可以选择性地阻断C型ENG齐射，但不能阻断A型齐射。在Cap期间具有最大强度的反射曲线与Cap之前的低强度压力反射没有区别。相比之下，迷走神经ENG显示C纤维齐射的分级Cap阻滞（ED50 = 200 nM），而低于1 microM的A型齐射没有明显衰减。但是，100 microM Cap阻断了所有带髓的迷走神经轴突以及C型轴突的传导。因此，Cap仅在低微摩尔浓度下对感觉C型轴突具有选择性。有髓和无髓动脉BR引起特征性的频率响应反射关系，提示感觉信息处理机制存在明显差异。

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