Delpierre S, Balzamo E, Jammes Y
Laboratoire de Physiologie Respiratoire, Faculté de Médecine Timone, Marseille, France.
Neurosci Lett. 1998 Oct 9;255(1):29-32. doi: 10.1016/s0304-3940(98)00705-8.
Breathing through an inspiratory resistance induces a hypoventilation in mammals despite an increased diaphragmatic activity. We showed in previous works that an increase in GABA and endogenous opioid release in the central respiratory network could explain in part the inadequate increase in the inspiratory drive during inspiratory loading. In the present experiment, we speculated about an additional role of glycine, another inhibitory neurotransmitter. The ventilatory effects of the glycine antagonist strychnine were evaluated in two groups of anesthetized rabbits, breathing either through an inspiratory resistive load (IRL) or not (control group). In the control group, strychnine raised (+7%, P < 0.05) the minute ventilation, V, and the rate of increase in integrated diaphragmatic discharge (Edi peak/T peak: +29%, P < 0.01). In the IRL group, strychnine did not change V and produced a lesser increase in Edi peak/T peak (+9%, P < 0.05). In both groups, strychnine induced a tonic diaphragmatic discharge. These data show that there is a weak inhibition of inspiration by glycine during resistive loading, but the effect is modest compared with that observed during unloaded ventilation. Thus, it seems that IRL breathing reduces the efficacy and/or the release of this neurotransmitter in the central nervous system, in this experimental situation.
在哺乳动物中，通过吸气阻力进行呼吸会导致通气不足，尽管膈肌活动增强。我们在先前的研究中表明，中枢呼吸网络中γ-氨基丁酸（GABA）和内源性阿片类物质释放的增加可以部分解释吸气负荷期间吸气驱动增加不足的现象。在本实验中，我们推测了另一种抑制性神经递质甘氨酸的额外作用。在两组麻醉兔中评估了甘氨酸拮抗剂士的宁的通气效应，一组通过吸气阻力负荷（IRL）呼吸，另一组不通过吸气阻力负荷呼吸（对照组）。在对照组中，士的宁使分钟通气量（V）增加了7%（P < 0.05），膈肌放电积分增加率（Edi峰值/T峰值）增加了29%（P < 0.01）。在IRL组中，士的宁没有改变V，并且Edi峰值/T峰值的增加幅度较小（+9%，P < 0.05）。在两组中，士的宁均诱导了持续性膈肌放电。这些数据表明，在阻力负荷期间甘氨酸对吸气有微弱的抑制作用，但与无负荷通气时观察到的效果相比，这种作用较小。因此，在这种实验情况下，IRL呼吸似乎降低了中枢神经系统中这种神经递质的效能和/或释放。
