Study on the difference in the circulatory response elicited with trigeminal stimulation

使用成年白色家兔。颏神经和眶下神经刺激采用10 s的方波脉冲，脉冲宽度0.1-0.75ms，频率1- 50 Hz，强度1- 20 V。当刺激频率为5 Hz，强度为5- 10 V，持续时间为0.25ms时，血压下降最明显，刺激眶下神经的反应大于刺激颏神经。在较高频率和较大强度的刺激下，血压先下降后上升。这种差异提示抑制反应和降压反应的途径不同。刺激方式为方波10 s，频率10- 50 Hz，强度1- 10 V，持续时间0.1-0.75ms。刺激主动脉神经引起的血压下降在25 Hz以上的较高频率时变得明显，心率下降比刺激三叉神经引起的更明显。与三叉神经刺激相比，从刺激开始到低血压达到峰值所需的时间更长。主动脉神经和三叉神经的反应不同，这是因为刺激传导的延髓通路和迷走神经活动不同，而且眶下神经和主动脉神经的电刺激是同时进行的。同时刺激引起的血压和心率的下降幅度大于单一神经刺激引起的血压和心率的下降幅度。然而，同时刺激的独特反应不能被检查，三叉神经降压反应和压力感受性反射的关系也不清楚。

Adult white rabbits were used. The mental nerve and the infraorbital nerve were stimulated by 10s of square pulses, 0.1-0.75ms in duration, 1-50Hz in frequency and 1-20V in strength. At the stimulus frequency of 5Hz, strength of 5-10V and duration of 0.25ms, blood pressure decreased most markedly and the response to the stimulation of the infraorbital nerve was larger than that of the mental nerve. At the stimulus of higher frequency and greater strength, blood pressure fell at first and then rose. This discrepancy suggested that pathways of suppressor response and depressor response were different.Subsequently, the aortic nerve was stimulated. The stimulus mode was 10s of the square wave, 10-50Hz in frequency, 1-10V in strength, 0.1-0.75ms in duration. Falling in blood pressure elicited with the stimulation of the aortic nerve became obvious at higher frequency over 25Hz and decrease in heart rate was more remarkable than that elicited with the trigeminal nerve stimulation. It took more time from the beginning of the stimulation to the peak of low blood pressure compared with the trigeminal nerve stimulation. Response of the aortic nerve and that of the trigeminal nerve were different because there were differences in the medullary pathway of the stimulus conduction and in the vagal nerve activity.Furthermore, the electric stimulation of the infraorbital nerve and the aortic nerve was carried out simultaneously. Decreases of blood pressure and heart rate elicited with simultaneous stimulation were greater than that elicited with single nerve stimulation. However, the unique reaction by simultaneous stimulus could not be checked and the relation of the trigeminal depressor response and baroreflex did not become clear.