TY - JOUR
T1 - Tracheal tone and the role of ionotropic glutamate receptors in the nucleus ambiguus
AU - Mueller, Patrick J.
AU - Buckwalter, John B.
AU - Clifford, Philip S.
PY - 2004/9/17
Y1 - 2004/9/17
N2 - Excitatory amino acid (EAA) transmission in the rostral portion of the ventrolateral medulla (RVLM) appears to be required for reflex airway constriction. The purpose of the present study was to determine whether our prior observations of right sided dominance are also reflected at the level of the RVLM, particularly at the right nucleus ambiguus (NA). Microinjection of glutamate (109 nl, 100 mM) into the right NA of anesthetized dogs produced significant increases in tracheal smooth muscle tone as assessed by pressure changes in a saline filled cuff of the endotracheal tube (Δ15±2 mm Hg). Increasing inspired CO 2 increased tracheal cuff pressure (Δ33±2 mm Hg) which was abolished by microinjections of the EAA antagonist kynurenic acid (109 nl, 100 mM) or the non-NMDA antagonist 6-nitro-7-sulfamobenzoquinoxaline-2,3-dione (NBQX, 109 nl, 10 mM) into the right NA. These results confirm that EAA receptors in the right NA are capable of modulating tracheal tone and suggest that non-NMDA receptors in the right NA are required for reflex airway constriction produced by systemic hypercapnia. Furthermore, the effects of right-sided NA microinjections in the present study, although not completely definitive, are consistent with previous studies that suggest dominant control of canine tracheal tone by the right vagus.
AB - Excitatory amino acid (EAA) transmission in the rostral portion of the ventrolateral medulla (RVLM) appears to be required for reflex airway constriction. The purpose of the present study was to determine whether our prior observations of right sided dominance are also reflected at the level of the RVLM, particularly at the right nucleus ambiguus (NA). Microinjection of glutamate (109 nl, 100 mM) into the right NA of anesthetized dogs produced significant increases in tracheal smooth muscle tone as assessed by pressure changes in a saline filled cuff of the endotracheal tube (Δ15±2 mm Hg). Increasing inspired CO 2 increased tracheal cuff pressure (Δ33±2 mm Hg) which was abolished by microinjections of the EAA antagonist kynurenic acid (109 nl, 100 mM) or the non-NMDA antagonist 6-nitro-7-sulfamobenzoquinoxaline-2,3-dione (NBQX, 109 nl, 10 mM) into the right NA. These results confirm that EAA receptors in the right NA are capable of modulating tracheal tone and suggest that non-NMDA receptors in the right NA are required for reflex airway constriction produced by systemic hypercapnia. Furthermore, the effects of right-sided NA microinjections in the present study, although not completely definitive, are consistent with previous studies that suggest dominant control of canine tracheal tone by the right vagus.
KW - Airway smooth muscle
KW - Bronchoconstriction
KW - Glutamate
KW - Parasympathetic control
UR - http://www.scopus.com/inward/record.url?scp=4344589936&partnerID=8YFLogxK
U2 - 10.1016/j.brainres.2004.06.036
DO - 10.1016/j.brainres.2004.06.036
M3 - Article
C2 - 15328031
AN - SCOPUS:4344589936
SN - 0006-8993
VL - 1021
SP - 54
EP - 62
JO - Brain Research
JF - Brain Research
IS - 1
ER -