Contribution of NMDA receptors to activity of augmenting expiratory neurons in vagotomized cats.
To identify the NMDA receptor-mediated mechanism in augmenting expiratory (E2) neurons, the effects of systemic and local application of dizocilpine on spontaneous and evoked postsynaptic potentials (PSPs) were investigated in decerebrate and vagotomized cats. Intravenously applied dizocilpine reduced the inhibitory PSPs during inspiration and stage 1 expiration, but had little effect on the excitatory PSPs during stage 2 expiration. Iontophoresed dizocilpine caused a continuous hyperpolarization throughout the respiratory cycle. Dizocilpine had no effect on vagally evoked PSPs. These results suggest that the NMDA mechanisms are involved presynaptically in periodic postsynaptic inhibitions and postsynaptically in tonic excitation in E2 neurons.
Haji
A
A
Department of Pharmacology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan.
Okazaki
M
M
Takeda
R
R
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002415:Cats; D003655:Decerebrate State; D016291:Dizocilpine Maleate / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D007478:Iontophoresis; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000502:physiology*; D012143:Respiratory Physiological Phenomena / Q000187:drug effects; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D014628:Vagotomy; D014630:Vagus Nerve / Q000502:physiology
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D016202:N-Methylaspartate; D016291:Dizocilpine Maleate