Kobashi M, Adachi A
Department of Physiology, Okayama University Dental School, Japan.
Brain Res. 1996 Jan 8;706(1):21-9. doi: 10.1016/0006-8993(95)01174-9.
The present experiment was designed to elucidate the characteristics of the response of neurons in the dorsal motor nucleus of the vagus (DMV) to stimulation of the hepatoportal area by hypotonic as well as hypertonic solutions. Responses of 81 neurons that exhibited an antidromic response to electrical stimulation of the ventral gastric vagus were recorded in the left DMV in urethane-chloralose anesthetized rats. The effects on these 81 neurons of portal infusion of hypertonic saline (3.6% NaCl) and of pure water were examined. The discharge rates of 16 neurons increased in response both to portal infusion of hypertonic saline and to that of water. Portal infusion of 0.9% NaCl produced no changes in firing rates. Their discharge rates of seven neurons increased in response to portal infusion of hypertonic saline but not to that of water. The other 58 neurons did not respond to these stimuli. Jugular infusion of water produced no response. Therefore, the responses to portal infusion of water appear to be derived from activation of the hepatoportal receptors. These results indicate that a certain fraction of DMV neurons respond similarly to portal infusions of hypertonic and hypotonic saline. It is possible that there exist some reflex arcs that mediate a similar response to both an increase and a decrease in portal blood osmolarity (or Na+ concentration), namely, a suppression of absorption.
本实验旨在阐明迷走神经背运动核（DMV）中神经元对低渗和高渗溶液刺激肝门区的反应特征。在乌拉坦-氯醛糖麻醉的大鼠左侧DMV中，记录了81个对腹侧胃迷走神经电刺激表现出逆向反应的神经元的反应。研究了门静脉输注高渗盐水（3.6% NaCl）和纯水对这81个神经元的影响。16个神经元的放电频率在门静脉输注高渗盐水和纯水时均增加。门静脉输注0.9% NaCl对放电频率无影响。7个神经元的放电频率在门静脉输注高渗盐水时增加，但在输注纯水时未增加。其他58个神经元对这些刺激无反应。颈静脉输注水无反应。因此，对门静脉输注水的反应似乎源于肝门受体的激活。这些结果表明，一定比例的DMV神经元对门静脉输注高渗和低渗盐水的反应相似。可能存在一些反射弧介导对门静脉血渗透压（或Na+浓度）升高和降低的类似反应，即吸收抑制。
