Gaba receptors in the phrenic nucleus of the rat.
Chitravanshi, V. C., and H. N. Sapru.
Section of Neurological Surgery, New Jersey Medical School, Newark,
NJ 07103, (U.S.A.)
APStracts 5:0383R, 1998.
The phrenic nucleus was identified by microinjections of NMDA in
urethane-anesthetized adult, male Wistar rats. Microinjections of
GABAA and GABAB- receptor agonists (muscimol and baclofen,
respectively) at the same site decreased the phrenic nerve burst
-amplitude. Microinjections of GABAA and GABAB- receptor antagonists
(bicuculline and 2-hydroxysaclofen, respectively) blocked as well as
reversed the effects of their respective agonists. These results were
confirmed by recording extracellular action potentials from single
phrenic neurons. Micropressure applications of muscimol and baclofen
decreased the activity of single neurons in the phrenic nucleus; this
effect was blocked as well as reversed by micropressure applications
of bicuculline and 2-hydroxysaclofen, respectively. These results
demonstrated the presence of GABA receptors on the neurons in the
phrenic nucleus and suggested that their activation results in the
decrease of the phrenic nerve burst-amplitude. The importance of
these results in the identification of neural circuits mediating
inhibition of phrenic neurons is discussed.
Received 8 April 1998; accepted in final form 16 October 1998.
APS Manuscript Number R218-8.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 10 November 1998