Li W M, Liu X, Kumada M, Sato A
Department of Molecular and Cellular Physiology, Faculty of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan.
Jpn J Physiol. 1998 Aug;48(4):261-6. doi: 10.2170/jjphysiol.48.261.
The effect of baroreceptor activation on somato-cardiac sympathetic reflex discharges was examined in urethane-anesthetized, vagotomized, and artificially ventilated rats. Single shock stimulation of myelinated (A) and unmyelinated (C) fibers in the tibial nerve of the left hindlimb elicited two separate excitatory reflex discharge components in a branch of the cardiac sympathetic nerve. They are termed the A- and C-components of the somato-cardiac sympathetic reflex discharges. When aortic nerves (AN) and carotid sinus nerves (CSN) were intact, a sudden increase in mean arterial blood pressure to about 150 mmHg induced by I.V. injection of phenylephrine (50 micro/kg) depressed the A- and C-components by up to 47 +/- 5.4 and 37 +/- 7.7% of the control values, respectively. However, bilateral sino-aortic denervation completely abolished the pressure-induced depression of both components. We conclude that baroreceptor afferent signals from the AN and CSN inhibit both A- and C-components of the excitatory somato-cardiac sympathetic reflex discharges. This and other previous evidence mentioned in the text indicate that inhibitory cardiac sympathetic reflexes originating from arterial baroreceptors and excitatory ones originating from somatic afferents interact, probably at the brainstem.
在氨基甲酸乙酯麻醉、迷走神经切断并人工通气的大鼠中，研究了压力感受器激活对躯体 - 心脏交感神经反射放电的影响。对左后肢胫神经中的有髓（A）和无髓（C）纤维进行单次电击刺激，在心脏交感神经的一个分支中引发了两个独立的兴奋性反射放电成分。它们被称为躯体 - 心脏交感神经反射放电的A成分和C成分。当主动脉神经（AN）和颈动脉窦神经（CSN）完整时，静脉注射去氧肾上腺素（50微克/千克）使平均动脉血压突然升高至约150 mmHg，分别使A成分和C成分降低至对照值的47±5.4%和37±7.7%。然而，双侧窦主动脉去神经支配完全消除了压力诱导的两个成分的抑制作用。我们得出结论，来自AN和CSN的压力感受器传入信号抑制兴奋性躯体 - 心脏交感神经反射放电的A成分和C成分。本文提到的这一证据和其他先前的证据表明，源自动脉压力感受器的抑制性心脏交感神经反射和源自躯体传入神经的兴奋性反射可能在脑干相互作用。
