Cabot J B, Cohen D H
Brain Res. 1977 Aug 5;131(1):89-101. doi: 10.1016/0006-8993(77)90030-0.
In the preceding paper6 describing the right sympathetic cardiac nerve of the pigeon we reported a fast compound action potential component with no chronotropic effect, and single unit recordings from sympathetic postganglionic neurons demonstrated that this action potential component was not reflected in the antidromic postganglionic latencies. Electron microscopy then indicated the presence of numerous myelinated fibers in the nerve, and together these findings suggested the existence of a substantial number of sympathetic cardiac afferents in the right cardiac nerve. The present paper confirms this by demonstrating with retrograde transport of horseradish peroxidase that some fibers of the right sympathetic cardiac nerve have their cells of origin in dorsal root ganglia. This was also shown to be the case for the left sympathetic cardiac nerve. Selective activation of the myelinated fiber contingent was then shown to elicit a short latency decrease in arterial blood pressure that could be further augmented by the activation of the smaller unmyelinated fibers. This reflex depressor response to activation of sympathetic cardiac afferents survived bilateral vagotomy but was blocked by atropine. It is therefore concluded that both the left and right sympathetic cardiac nerves of the pigeon contain afferent fibers, both myelinated and unmyelinated, and that the reflex effect of activating these fibers is a sympathetically mediated vasodilation that is atropine-sensitive.
在之前一篇描述家鸽右侧交感心脏神经的论文6中，我们报告了一种快速复合动作电位成分，它没有变时效应，并且交感神经节后神经元的单单位记录表明，这种动作电位成分在逆向节后潜伏期并未体现出来。电子显微镜检查随后显示该神经中存在大量有髓纤维，综合这些发现表明右侧心脏神经中存在大量交感心脏传入纤维。本文通过辣根过氧化物酶逆行运输证明右侧交感心脏神经的一些纤维起源于背根神经节，从而证实了这一点。左侧交感心脏神经的情况也是如此。随后发现，选择性激活有髓纤维群体可引起动脉血压的短潜伏期下降，激活较小的无髓纤维可进一步增强这种下降。这种对交感心脏传入纤维激活的反射性降压反应在双侧迷走神经切断术后依然存在，但被阿托品阻断。因此得出结论，家鸽的左侧和右侧交感心脏神经均包含有髓和无髓的传入纤维，并且激活这些纤维的反射效应是一种由交感神经介导的、对阿托品敏感的血管舒张。
