Baclofen eliminates cluster lung breathing of the tadpole brainstem, in vitro.
Intermittent lung ventilation is a respiratory pattern wherein breaths occur in clusters. Intermittent lung ventilation is common in amphibians and can occur in mammals. Isolated brainstems from postmetamorphic tadpoles exhibiting episodic lung ventilatory bursts were superfused with baclofen, a potent gamma-aminobutyric acid (GABA)(B) receptor agonist. At moderate concentrations (0.125 to 0.5 microM), the number of lung bursts per episode decreased but their overall frequency was unchanged. At 0.5 microM, only 1.22+/-0.24 lung bursts occurred per episode, indicating virtually no clustering. Only at higher concentrations was overall breathing frequency decreased. Therefore, at moderate concentrations of baclofen continuous ventilation replaced episodic ventilation, suggesting that a GABA(B) receptor-dependent pathway may regulate the clustering of lung breaths.
Straus
C
C
Respiratory Research Group, Department of Medical Physiology, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Alberta, T2N 4N1, Calgary, Canada. christian.straus@psl.ap-hop-paris.fr
Wilson
R J
RJ
Tezenas du Montcel
S
S
Remmers
J E
JE
D000818:Animals; D001418:Baclofen / Q000494:pharmacology*; D001933:Brain Stem / Q000187:drug effects* / Q000502:physiology; D018755:GABA Agonists / Q000494:pharmacology; D066298:In Vitro Techniques; D007814:Larva / Q000502:physiology; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D011892:Rana catesbeiana; D018080:Receptors, GABA-B / Q000378:metabolism; D015656:Respiratory Mechanics / Q000187:drug effects* / Q000502:physiology
D018755:GABA Agonists; D009125:Muscle Relaxants, Central; D018080:Receptors, GABA-B; D001418:Baclofen