title: New insights in gill/buccal rhythm spiking activity and CO(2) sensitivity in pre- and postmetamorphic tadpoles (Pelophylax ridibundus).
abstract: Central CO(2) chemosensitivity is crucial for all air-breathing vertebrates and raises the question of its role in ventilatory rhythmogenesis. In this study, neurograms of ventilatory motor outputs recorded in facial nerve of premetamorphic and postmetamorphic tadpole isolated brainstems, under normo- and hypercapnia, are investigated using Continuous Wavelet Transform spectral analysis for buccal activity and computation of number and amplitude of spikes during buccal and lung activities. Buccal bursts exhibit fast oscillations (20-30Hz) that are prominent in premetamorphic tadpoles: they result from the presence in periodic time windows of high amplitude spikes. Hypercapnia systematically decreases the frequency of buccal rhythm in both pre- and postmetamorphic tadpoles, by a lengthening of the interburst duration. In postmetamorphic tadpoles, hypercapnia reduces buccal burst amplitude and unmasks small fast oscillations. Our results suggest a common effect of the hypercapnia on the buccal part of the Central Pattern Generator in all tadpoles and a possible effect at the level of the motoneuron recruitment in postmetamorphic tadpoles.
authors.affiliation: ESPCI-ParisTech, Equipe de Statistique Appliquée, F-75005 Paris, France. Electronic address: Brigitte.quenet@espci.fr.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Quenet
authors.affiliation: UPMC Univ Paris 06, ER 10 UPMC, F-75013 Paris, France; Assistance Publique - Hôpitaux de Paris, Groupe Hospitalier Pitié-Salpêtrière, Service Central d'Explorations Fonctionnelles Respiratoires, F-75013 Paris, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Straus
authors.affiliation: UPMC Univ Paris 06, ER 10 UPMC, F-75013 Paris, France.
authors.forename: Marie-Noëlle
authors.initials: MN
authors.lastname: Fiamma
authors.affiliation: ESPCI-ParisTech, Equipe de Statistique Appliquée, F-75005 Paris, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Rivals
authors.affiliation: UPMC Univ Paris 06, ER 10 UPMC, F-75013 Paris, France; Assistance Publique - Hôpitaux de Paris, Groupe Hospitalier Pitié-Salpêtrière, Service de Pneumologie et Réanimation Médicale, F-75013 Paris, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Similowski
authors.affiliation: ESPCI-ParisTech, Equipe de Statistique Appliquée, F-75005 Paris, France.
authors.forename: Ginette
authors.initials: G
authors.lastname: Horcholle-Bossavit
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D005154:Facial Nerve / Q000502:physiology; D005583:Fourier Analysis; D005880:Gills / Q000502:physiology*; D006935:Hypercapnia / Q000503:physiopathology; D066298:In Vitro Techniques; D007814:Larva / Q000502:physiology; D008675:Metamorphosis, Biological / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D012119:Respiration; D012125:Respiratory Center / Q000166:cytology* / Q000254:growth & development; D013997:Time Factors
keywords: Amphibian buccal ventilation; CWT spectrum; Central CO(2) chemosensitivity; Fast oscillations; Spiking activity