QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online August 30, 2006
Journal of Experimental Biology 209, 3685-3694 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02418

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fournier, S. Articles by Kinkead, R. Search for Related Content PubMed PubMed Citation Articles by Fournier, S. Articles by Kinkead, R.

Noradrenergic modulation of respiratory motor output during tadpole development: role of -adrenoceptors

Stéphanie Fournier and Richard Kinkead^*

Department of Pediatrics, Université Laval, Centre de Recherche du Centre Hospitalier Universitaire de Québec, 10 rue de l'Espinay, Québec City, QC G1L 3L5, Canada

View larger version (17K): [in a new window]   Fig. 1. Trigeminal neurograms comparing changes in lung- and buccal-related motor output with bath application of 5 µmol l-1 noradrenaline (NA) concentrations. These recordings illustrate the distinction between the two patterns of respiratory-related neural activity, and show the stage-dependent effects of NA on the neural correlates of respiratory activity. Recordings were obtained from isolated brainstem preparations from pre- and metamorphic tadpoles, and an adult bullfrog.

View larger version (21K): [in a new window]   Fig. 2. Stage-dependent changes in fictive lung burst frequency during noradrenaline (NA) application at different concentration. NA application was followed by a 30-90 min wash-out period. (A) Absolute lung burst frequency, (B) data expressed as a percentage change from baseline values. In A and B, responses were measured in pre-(triangles; N=12) and metamorphic tadpoles (squares; N=10), and adult frogs (circles; N=9). Values are expressed as means ± s.e.m. *Values statistically different from baseline at P<0.05. Values statistically different from corresponding pre-metamorphic value at P<0.05.

View larger version (18K): [in a new window]   Fig. 3. The effects of NA bath application (5 µmol l-1) on fictive lung (A,C) and buccal (B,D) ventilation frequencies in the presence of the selective -adrenoceptor antagonist prazosine (Pra; 0.5 µmol l-1; A,B) or the selective 2-adrenoceptor antagonist RX821002 (RX; 25 µmol l-1; C,D). These experiments were performed on brainstem preparations from pre-metamorphic tadpoles (grey bars) and adult bullfrogs (black bars). *Values statistically different from baseline at P<0.05. **Values statistically different from baseline at P<0.10.

View larger version (20K): [in a new window]   Fig. 4. Dose-dependent changes in fictive buccal burst frequency during noradrenaline (NA) application at different concentrations. NA application was followed by a 30-90 min wash-out period. (A) Absolute buccal burst frequency, (B) frequency data expressed as a percentage change from baseline values. In A and B, data were obtained in pre-(triangles; N=11) and metamorphic tadpoles (squares; N=7), and adult frogs (circles; N=4). Values are expressed as means ± s.e.m. *Values statistically different from baseline at P<0.05.

View larger version (23K): [in a new window]   Fig. 5. Dose-dependent changes in fictive lung and buccal burst frequency during application of increasing concentration of the 1-adrenoceptor agonist phenylephrine (Phe). Phe application was followed by a 30-90 min wash-out period. (A) Data expressed as a percentage change from lung baseline values, and (B) data expressed as a percentage change from buccal baseline values. In A, lung burst frequency responses were measured in pre-(triangles; N=6) and metamorphic tadpoles (squares; N=12), and adult frogs (circles; N=10). For fictive buccal burst frequency responses (B), mean data were obtained in pre-(N=8) and metamorphic tadpoles (N=13), but not in adult frogs (N=1). Adults were excluded from the statistical analysis since the number of replicates was too low; for this group, data are displayed without error bars. Values are expressed as means ± s.e.m. *Values statistically different from baseline at P<0.05. **Values statistically different from baseline at P<0.10. Values statistically different from corresponding values from the pre-metamorphic group at P<0.05.

View larger version (21K): [in a new window]   Fig. 6. Dose- and stage-dependent changes in fictive lung and buccal burst frequency during application of increasing concentration of the 2-adrenoceptor agonist clonidine (Clo). Clo application was followed by a 30-90 min wash-out period. (A) Data expressed as a percentage change from baseline lung values, and (B) data expressed as a percentage change from baseline buccal values. In A, lung burst frequency responses were measured in pre-(triangles; N=9) and metamorphic tadpoles (squares; N=7), and adult frogs (circles; N=12). For fictive buccal burst frequency responses (B), mean data were obtained in pre-(N=9) and metamorphic tadpoles (N=6), and adult frogs (N=2). Adults were excluded from the statistical analysis since the number of replicates was too low; for this group, data are displayed without error bars. Values are expressed as means ± s.e.m. *Values statistically different from baseline, P<0.05. **Values statistically different from baseline, P<0.10. Values statistically different from corresponding values from the pre-metamorphic group, P<0.05.