Walter M St -John

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This study evaluated possible neuronal mechanisms responsible for the transition from normal breathing (eupnea) to gasping. We hypothesized that a blockade of both inhibitory glycinergic synaptic transmission and potassium channels, combined with an increase in extracellular concentration of potassium, would induce a switch from an eupneic respiratory(More)
During eupnea in an in situ perfused preparation of the rat, inspiratory activities of the hypoglossal and vagal nerves commence before the phrenic; the vagus also discharges in expiration. The hypoglossal discharge has a prominent "pre-inspiratory" component. Power spectral analysis indicated that peak frequencies of oscillations in phrenic, hypoglossal(More)
The perfused in situ juvenile rat preparation produces phrenic discharge patterns comparable to eupnea and gasping in vivo. These ventilatory patterns of eupnea and gasping differ in multiple aspects, including most prominently the rate of rise of inspiratory activity. Because gasping, but not eupnea, appeared similar after vagotomy in spontaneous breathing(More)
In vivo, the augmenting pattern of integrated phrenic nerve discharge of eupnea is altered to the decrementing pattern of gasping in severe hypoxia or ischaemia. Identical alterations in phrenic discharge are found in perfused in situ preparations of the juvenile rat. In this preparation, gasping was produced by equilibration of the perfusate with various(More)
To describe a pattern of rhythmic activity as "breathing" or "respiration" inevitably leads to the conclusion that this rhythmic activity is "normal" or "eupneic". Initially, it must be noted that, by strictest definition, "eupnea" can only be applied to "breathing" in an unanesthetized preparation. Any experimental perturbation, including anesthesia,(More)
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