摘要
40只家兔,乌拉坦静脉麻醉。切断双侧主动脉神经(AN)、窦神经及迷走神经。以选择兴奋 AN 有髓传人纤维的条件刺激(0.02ms,50Hz,4—6V,5min)给予切断的 AN 中枢段,模拟导致低阈压力感受反射快速重调的保持压背景,借以诱导快速重调的中枢过程。实验表明:该中枢过程使 AN 有髓纤维传入所激发的压力感受反射降压效应衰减41.82%(P<0.01),肾交感神经活动抑制效应衰减19.31%(P<O.05),并延缓各反应过程;但不影响 AN 无髓纤维传入激发的压力感受反射。提示:压力感受反射快速重调的中枢过程,对压力感受反射的衰减性影响依赖于传入纤维成分,低阈有髓纤维兴奋所诱导的中枢重调过程,仅衰减有髓纤维传入激发的压力感受反射。
Experiments were performed on 40 urethane-anesthetized rabbits.Theaortic nerves,carotid sinus nerves and vagus nerves were cut,mean arterial pres-sure(MAP)and renal sympathetic nerve activity(RSNA)were recorded.Theconditional stimulation(0.02ms,50Hz,4—6V,5 min)of central cut end of aorticnerve was used to evoke the afferent A-fibers and to mimic the response of lowthreshold baroreflex to holding pressure,so as to induce the central process ofacute resetting.It was observed that after conditional stimulation ceased 1 min,the MAP and RSNA for response to stimulation of myelinated aortic afferent wasattenuated at 41.8±7.6%(P<0.01,n=11)and 19.31±2.6%(P<0.05,n=11),but both MAP and RSNA were not significantly changed for non-myelinatedfibers.The result suggests that the characteristics of central resetting were depend-ent on the component of baroreflex afferent fibers.The central resetting of lowthreshold myelinated afferent activities was attenuated only on the baroreflexproduced by myelinated afferent fibers.
出处
《生理学报》
CAS
CSCD
北大核心
1991年第3期296-301,共6页
Acta Physiologica Sinica
基金
国家自然科学基金
省卫生厅资助
