Two regions in the isolated brainstem of the frog that modulate respiratory-related activity |
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Authors: | H A McLean S F Perry J E Remmers |
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Institution: | (1) Departments of Medicine and Physiology, Faculty of Medicine, University of Calgary, T2N 4N1 Calgary, AB, Canada;(2) Present address: INSERM Unité 29, Hôpital de Port-Royal, 123 Boulevard de Port-Royal, F-75674 Paris Cedex 14, France;(3) Present address: Zoologisches Institut der Universität Bonn, D-53115 Bonn, Germany |
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Abstract: | Using microinjection techniques, we have explored the isolated, complete midline sectioned brainstem of the frog (Rana catesbeiana) to identify regions that influence the endogenous respiratory-related motor activity. Ten-nanoliter injections of lidocaine (1%), GABA (100 mM) and glutamate (10 and 100 mM) into discrete regions of the rostral and the caudal brainstem produced different effects on the phasic neural discharge. In the rostral site lidocaine, GABA and glutamate injections altered neural burst frequency with little or no effect on burst amplitude. In the caudal site, responses to lidocaine and GABA injections consisted primarily of decreases in neural burst amplitude, often, but not always associated with minor decreases in burst frequency. In this same region, the response to glutamate was characterized by a temporary interruption of the rhythmic neural burst activity. The largest responses to substance injection in both regions were obtained at sites ranging between 200 and 500 m from the ventral surface, in the ventral medullary reticular formation. The results reveal the existence of two areas in the frog brainstem that influence respiratory motor output, one related to the respiratory burst frequency and the other related to the amplitude of the motor output.Abbreviations
V
trigeminal nerve
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VI
abducens nerve
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VII
facial nerve
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VIII
auditory nerve
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X
vagal nerve
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H
hypoglossal nerve
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VRG
ventral respiratory group
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NTS
nucleus of the solitary tract |
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Keywords: | Pressure injection Neural control of breathing Amphibian Respiratory rhythmogenesis |
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