Study of pathways of trigemino-cardiovascular reflex and central control

电刺激频率为5 Hz、强度为5 mA和20 mA的三叉神经可引起家兔低血压和心动过缓。当血压下降时，交感神经活动减少。本研究采用成年白色家兔，研究脑干通路介导三叉神经刺激引起的血流动力学。在乌拉坦和α-氯醛糖麻醉下，动物人工通气。在50 Hz的刺激频率下，血压先下降后上升。从刺激开始到高压达到峰值需要4.2s，到低压达到峰值需要11.6s。这种差异表明抑制反应和降压反应的途径不同。在下一个实验中，评价了吸入麻醉剂（异氟烷和七氟烷）对电刺激精神神经产生的心血管和自主神经变化的影响。在较低浓度下，刺激精神神经引起交感神经活动减少，在较高浓度下，刺激精神神经引起交感神经活动增加。我们假设有两个系统控制交感神经活动，即抑制系统和降压系统，这些系统对吸入剂的敏感性是不同的。此外，我们在三叉神经脊束复合体（STC），头端腹外侧延髓（RVLM），尾端腹外侧延髓（CVLM）的高度局部加热的小的损害。电刺激三叉神经引起的降压反应减弱，但抑制反应无明显变化。提示延髓内存在两条通路。在RVLM和CVLM中进行损伤后，反应没有改变。这些区域在三叉神经刺激的传导中似乎并不重要。

Electrical stimulation of the trigeminal nerve caused hypotension and bradycardia in rabbits at the stimulus frequency of 5 Hz and strengths of 5 mA and 20 mA. Activities of the sympathetic nerve decreased when blood pressure fell. In this study, we examined brainstem pathways mediating hemodynamics elicited by trigeminal stimulation.Adult white rabbits were used. Under urethane and α-chloralose anesthesia, animals were ventilated artificially. At the stimulus frequency of 50 Hz, blood pressure fell at first and then rose. It took 4.2 s from the beginning of stimulation to the peak of high pressure, and 11.6 s to the peak of low pressure. This discrepancy suggested that pathways of suppressor response and depressor response were different. In the next experiment, effects of inhalation anesthetics (isoflurane and sevoflurane) on cardiovascular and autonomic changes generated by electrical stimulation of the mental- nerve were evaluated. At lower concentration, stimulation of the mental nerve caused a decrease in sympathetic nervous activity and at higher concentration, it caused an increase in sympathetic nerve activity. We hypothesized that there were two systems that controlled sympathetic nervous activity i.e. a suppressor system and a depressor system and that sensitivities of these systems to inhalation agents were different. Furthermore, we made small lesions in spinal trigeminal complex (STC), rostral ventrolateral medulla (RVLM), caudal ventrolateral medulla (CVLM) by highly localized heating. After making lesions in STC, depressor response elicited by trigeminal electrical stimulation became little but suppressor response did not change. It suggested that there were two pathways in medulla. After making lesions in RVLM and CVLM, responses did not change. It seemed that these regions were not important in conduction of trigeminal stimulation.