[Mechanisms of effects of electrical stimulation of "Renzhong" (Du 26) on phrenic discharge in rabbits].

Experiments were performed on urethane anesthetized, bivagotomized, flaxedil paralyzed and artificially ventilated rabbits. The effects of stimulation of "Renzhong" (Du 26) on phrenic discharge were not caused secondarily by blood pressure alteration. The effects were abolished by bilateral section of infraorbital nerves, were similar to those of stimulation of the central end of the infraorbital nerve, and were not qualitatively changed by mid-colliculi decerebration. The responses of the bulbar respiratory related neurons were coordinated with those of the phrenic nerve to stimulation of "Renzhong", i.e., the responses of almost all of the inspiratory neurons were consistent with phrenic responses and those of the most of the expiratory neurons were contrary to them. It can be concluded that the effects of electrical stimulation of "Renzhong" on phrenic discharge result from the nervous reflex. Its afferent is infraorbital nerve and the higher centers are not essential for it. The bulbar respiratory related neurons might play an important part in it.