Kitano S, Komatsu A
Department of Physiology, Tokyo Women's Medical College, Japan.
Brain Res. 1988 Jan 26;439(1-2):19-30. doi: 10.1016/0006-8993(88)91457-6.
To investigate properties of the central respiratory oscillator, phrenic nerve activity, perturbed by electrical stimulation of the middle external intercostal nerve, was analyzed in rabbit by using a phase-response curve (PRC). During inspiration, the stimuli (4-8 pulses) caused all-or-none responses, i.e. a phase advance or no phase shift, and strong stimuli (10 pulses) induced only phase advances. During expiration only graded phase delays were observed. The overall slope of PRC was 0 for 2 pulses and 1 for 10 pulses. At the transition from expiration (E) to inspiration (I), the PRC was discontinuous. This discontinuity corresponds to a phase singularity. In contrast, at the transition from I to E, the PRC was continuous. Therefore, our findings indicate that E-I switching may differ from I-E switching in nature. The respiratory rhythm could not be stopped by perturbation at the phase singularity as predicted from the PRCs. Similarities between the reported PRCs, obtained by inhibitory stimulation of an endogenous bursting neuron and the PRCs in the present study, suggest a possibility that endogenous bursting neurons take part in the function of a mammalian central respiratory oscillator.
为了研究中枢呼吸振荡器的特性，通过使用相位响应曲线（PRC），对兔中因肋间外肌中间神经电刺激而受到扰动的膈神经活动进行了分析。在吸气期间，刺激（4 - 8个脉冲）引起全或无反应，即相位提前或无相位偏移，而强刺激（10个脉冲）仅诱导相位提前。在呼气期间仅观察到分级相位延迟。PRC的整体斜率对于2个脉冲为0，对于10个脉冲为1。在从呼气（E）到吸气（I）的转变过程中，PRC是不连续的。这种不连续性对应于一个相位奇点。相反，在从I到E的转变过程中，PRC是连续的。因此，我们的研究结果表明，E - I转换在本质上可能与I - E转换不同。如从PRC所预测的那样，在相位奇点处的扰动并不能停止呼吸节律。通过对一个内源性爆发神经元的抑制性刺激获得的所报道的PRC与本研究中的PRC之间的相似性表明，内源性爆发神经元可能参与哺乳动物中枢呼吸振荡器功能的可能性。
