Phase switching of respiratory rhythm in bulbar respiratory neuronal network

点击翻译按钮获取中文摘要

To investigate the phase transitional process of respiratory rhythm generation, inspiratory off-switching (LOS) and on-switching (IonS), membrane potential and postsynaptic potentials were recorded from bulbar respiratory neurons in decerebrate, unanesthetized, vagotomized, artificially ventilated cats. The following results were obtained.1. Eupneic respiration was generated within the bulbar respiratory neuronal network without pulmonary afferent inputs and pontine pneumotaxic inputs.2. During IOS, a sequential excitation of late-I neurons and P1 neurons inhibited the inspiratory activity of aug-I neurons. Blockade of NMDA receptors resulted in apneusis by impairing this lOS mechanism. During apneusis, IOS was induced by excitation of E2 neurons through activation of non-NMDA receptors.3. During IOS, the final inhibitory transmission to aug-I neurons was mediated by the GABA-A receptor mechanism.4. Short latency postsynaptic potentials were evoked in bulbar respiratory neurons during IOS induced by vagal stimulation. These postsynaptic responses were similar to those during the vagally induced IonS.5. Low-threshold Ca currents involved in the rebound depolarization of respiratory neurons at the transitional phase from the inactive phase to the active phase.