Hamada O, Garcia-Rill E, Skinner R D
Department of Anatomy, University of Arkansas for Medical Sciences, Little Rock 72205.
Somatosens Mot Res. 1992;9(4):313-26. doi: 10.3109/08990229209144780.
The present report describes respiratory-like activity recorded from intercostal muscles in the neonatal rat in vitro brain stem-spinal cord, rib-attached preparation. In this preparation from 1- to 4-day-old rats, spontaneous rhythmic and synchronized upward movements of the rib cage coincided with the recorded muscle activity. Spontaneous respiratory-like activity showed a frequency in the range of 0.05-0.2 Hz, with single-, double-, and mixed-burst patterns. Spontaneous activity declined over time, but increased in frequency as temperature increased. Multilevel recordings showed a cephalocaudal order of bursting of intercostal muscles. Brain stem transections at the prepontine level did not affect spontaneous frequency, whereas premedullary transections resulted in an increase in spontaneous respiratory frequency. High spinal transections eliminated spontaneous respiratory-like activity. These results suggest that there is a well-organized pontomedullary pattern generator for respiratory-like activity in this preparation, which can be modulated by temperature. The characteristics of these electromyographic (EMG) recordings allow comparison with previous in vitro studies of respiratory-like activity using nerve activity and in vivo studies using EMG activity. These results provide basic information on the spontaneous activity of this preparation as a prelude to the study of the effects of electrical stimulation of the spinal cord to induce respiratory-like activity, as described in the companion article.
本报告描述了在新生大鼠体外脑干 - 脊髓、附肋制备物中肋间肌记录到的类似呼吸的活动。在这种取自1至4日龄大鼠的制备物中，胸廓自发的节律性同步向上运动与记录到的肌肉活动同时出现。自发的类似呼吸的活动频率在0.05 - 0.2赫兹范围内，具有单爆发、双爆发和混合爆发模式。自发活动随时间下降，但随着温度升高频率增加。多级记录显示肋间肌爆发存在头 - 尾顺序。脑桥前水平的脑干横切不影响自发频率，而延髓前横切导致自发呼吸频率增加。高位脊髓横切消除了自发的类似呼吸的活动。这些结果表明，在这种制备物中存在一个组织良好的脑桥 - 延髓模式发生器用于类似呼吸的活动，其可受温度调节。这些肌电图（EMG）记录的特征允许与先前使用神经活动进行的类似呼吸活动的体外研究以及使用EMG活动进行的体内研究进行比较。这些结果提供了关于这种制备物自发活动的基本信息，作为如配套文章中所述研究脊髓电刺激诱导类似呼吸活动效果的前奏。
