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Blockade of synaptic inhibition within the pre‐Bötzinger complex in the cat suppresses respiratory rhythm generation in vivo
Author(s) -
Pierrefiche O.,
Schwarzacher S. W.,
Bischoff A. M.,
Richter D. W.
Publication year - 1998
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1998.245bo.x
Subject(s) - strychnine , bicuculline , phrenic nerve , tetrodotoxin , tonic (physiology) , glycine receptor , gaba receptor antagonist , neuroscience , blockade , chemistry , anesthesia , respiratory system , pharmacology , biology , medicine , glycine , receptor , gabaa receptor , biochemistry , amino acid
1 The role of synaptic inhibition in respiratory rhythm generation was analysed by microinjections of GABA A and glycine receptor antagonists into the bilateral pre‐Bötzinger complex (PBC) of anaesthetized cats. Central respiratory activity was monitored by phrenic nerve recordings. 2 Bilateral injections of bicuculline (50 or 100 μ m ) irreversibly slowed respiratory frequency and induced apneustic patterns. 3 Bilateral injections of strychnine (50 or 100 μ m ) greatly reduced phrenic burst amplitudes leading to increased burst frequency or irreversibly blocked rhythmic phrenic discharges. After unilateral tetrodotoxin (TTX) blockade in the PBC, strychnine injection into the contralateral PBC blocked rhythmic phrenic discharges. 4 Bilateral blockade of both GABAergic and glycinergic inhibition abolished rhythmic burst discharges and only tonic phrenic activity remained. Such tonic activity was blocked only by TTX (1 μ m ). 5 Potentiation of synaptic inhibition by the serotonin 1A receptor agonist 8‐hydroxydipropylaminotetralin (8‐OH‐DPAT; 50 μ m ) restored rhythmic activity only when given shortly after strychnine and bicuculline applications. It was, however, ineffective after blockade of synaptic inhibition was complete. 6 The study demonstrates the significance of synaptic inhibition in the process of respiratory generation in the adult cat in vivo .