Differentiation of the cardio vascular center of the medulla

本实验在麻醉（乌拉坦1g/kg iv）和制动的家兔上进行，目的是鉴定延髓中i）皮肤血管收缩神经，ii）心脏交感神经，iii）肌肉血管收缩神经和iv）内脏血管收缩神经的运动前神经元。下丘脑温度调节中心（下丘脑前部视前区，POAH）的蠕动引起皮肤血管舒张。使用这种反应，网状脊髓（从脊髓逆向激活）神经元，其活动减少蠕虫的POAH在延髓头端搜索。头端腹内侧网状结构中的部分网状脊髓神经元对这种蠕虫刺激表现出抑制性反应，其时间反应模式与皮肤交感神经的反应非常相似。吸入低氧（3%）可抑制兔心交感神经的活动，降低心率。使用这种反应，前运动神经元在延髓头端腹外侧（RVLM）搜索。吸入低氧可抑制RVLM内约20%的压力敏感性网状脊髓神经元。因此，这些神经元被认为是心交感神经的运动前神经元。我们成功地确定了两种运动前神经元在延髓，这些数据将很快发表。

The aim of this project is to identify premotor neurons in the medulla for i)cuataneous vasoconstrictors, ii)cardiac sympathetic nerve, iii)vasoconstrictors of muscles and iv)vasoconstrictors of the visceral organs.Experiments were performed in anesthetized (Urethane 1g/kg iv)and immobilized rabbits. Worming of the thermoreguratory center of the hypothalamus (the preoptic area of the anterior hypothalamus, POAH) evokes vasodilation of the skin. Using this response, reticulospinal (antidromically activated from the spinal cord) neurons whose activity reduced by worming of the POAH were searched in the rostral medulla. Some reticulospinal neurons in the rostral ventormedial reticular formation showed inhibitory response to this worm stimulation and its temporal response patters were very similar to responses of the cutaneous sympathetic nerves. Therefore, these neurons were concluded as candidates of the premotor neurons for the cutaneous vasoconstrictors.Inhalation of the low oxygen gas (3%) inhibits activity of the cardiac sympathetic nerves and reduces heart rate in vagotomized rabbits. Using this response, premotor neurons were searched in the rostral ventrolateral medulla (RVLM). About 20% of barosensitive reticulospinal neurons in the RVLM were inhibited by inhalation of low oxygen gas. Therefore, these neurons were thought to be premotor neurons for cardiac sympathetic nerves.We succeeded to identify two kinds of premotor neurons in the medulla and these data will be published soon.