The ventral root reflex response (VRR) of the isolatcd spinal cord of the toad was observed by stimulating the sciatic nerve with various intensity. It was found that VRR was composed of an early phase and late Phase of dischage. To measure the area of dischagc with the integrator we found that it mainly reflected the change of the late phase, when the A?.? fibers in the sciatic nerve were excited, the area of VRR rea ehed 66% of the total area. When the A fibers were excited the area of VRR reach ed about 91% of the total area. Even though C fibers were excited with increasing, the intensity, the area of VRRwas not increased any more. This indicated that C fibers might not be involved in inducing VRR.After A?.? fibers were excited, the early phase of VRR had reached 96% of it's total amplitude. When the stimulus intensity was increased to be strong enough to excite A and C fibers, the amplitude of carly phase was not changed anymore indicating that A and C fibers are not relative to producing early phase of VRR,After A fibers were blocked by D-C current,the VRR disappeared immediately. When C fibers were blocked by Procaine, the VRR is not changed anymore, Showing that VRR is indueed only by A fibers.

The effects of morphine and its antagnoist naloxone on the VRR were studied. Morphine, at lower concentration (3.5 ? 10~(-7)～10~(-5)M), enhanced the VRR of toad spinal cord. This effect is proportional to its concentration within certain range, even though it depressed the ARR at higher concentration (5.3?10~(-5)-8.08?10~(-5)M). When naloxone was given alone. it did not excite or depress the VRR. While the VRR was enhanced by morphine, naloxone could antagonixe the exciting effect of the former. Experiments showed that naloxone could antagonize the exciting effect on the VRR produced by morphine.

Background Civil aviation pilots are actual operators of civil aircraft. Their job operations are directly associated with passenger safety and flight safety. Unsafe aviation operations are related to fatigue caused by poor sleep quality. Recently, with the promotion of China's air transportation business, irregular working hours of civil aviation pilots rise gradually. However, there is still a lack of relevant research on the influence of working conditions on sleep quality in this group. Objective To explore potential impact factors of sleep quality among civil aviation pilots, for the purposes of improving sleep quality and health level of this group and ensuring aviation flight safety by formulating health management suggestions in a targeted manner. Methods All pilots of an aviation company were approached when they visited the Shanghai Hospital of Civil Aviation Administration of China for their health examinations. After informed consent, an online questionnaire survey was conducted. Self-made questionnaires were used to collect information on general conditions, lifestyle, and subjective work stress levels. The Pittsburgh Sleep Quality Index (PSQI) was used to assess sleep quality. A total of 1204 valid questionnaires were recovered. Statistical analysis was conducted using SPSS 26.0 software. Results There were 410 pilots (16.8%) who reported sleep disorders, including insufficient sleep time, difficulty falling asleep, and poor sleep quality, and 894 pilots (74.3%) who reported moderate to severe work stress. Associations were identified between sleep quality of pilots and work stress or lifestyle indicators (P<0.05), while work stress showed the strongest association (r=0.28). Further multiple-factor analysis results showed that severe work stress (OR=4.25, 95%CI: 2.89, 6.30) and alcohol use (OR=1.72, 95%CI: 1.31, 2.27) associated with an increased risk of sleep disorders. Regular breakfast (OR=0.62, 95%CI: 0.42, 0.91) and physical exercise (OR=0.68, 95%CI: 0.45, 1.03) associated with a lower risk of sleep disorders. Conclusion A certain degree of sleep disturbance is reported in the civil aviation pilot group, which is closely related to work stress and lifestyle indicators. Targeted measures must be taken to effectively improve the quality of their sleep.