[Effect of electrical and L-glutamate stimulation of nucleus raphe obscurus on phrenic nerve activity in rabbits].
Experiments were performed on 45 urethane-anesthetized, vagotomized and spontaneously breathing rabbits. By electrical stimulation of or microinjection of L-glutamate into nucleus raphe obscurus (NRO), the following results were observed: (1) A long stimulus train (50-200 microA, 100Hz, 4-6 s) delivered to NRO resulted in a decrease in integrated phrenic amplitude (IPA) or complete cessation of phrenic nerve discharge. The decrease of IPA was dependent upon current intensity and frequency of stimulation. (2) Short train stimulation (100-200 microA, 50-100 Hz, 5-20 pulses) delivered to NRO during the inspiratory phase terminated this phase prematurely, i.e., inspiratory off-switch (IO-S). The IO-S time varied according to the current intensity and the delivery time of stimulation in the inspiratory phase. (3) Microinjection of L-glutamate (1 mol/L, 1 microliter) into NRO caused a transient depression of phrenic nerve activity followed by a shortening of inspiratory time (Ti) and a lengthening of expiratory time (Te).
Man
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Department of Physiology, Shandong Medical University, Jinan.
Liu
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D000818:Animals; D004558:Electric Stimulation; D004594:Electrophysiology; D008845:Microinjections; D010791:Phrenic Nerve / Q000502:physiology*; D011817:Rabbits; D011903:Raphe Nuclei / Q000502:physiology*; D012119:Respiration / Q000502:physiology*; D012970:Sodium Glutamate / Q000494:pharmacology*
D012970:Sodium Glutamate