HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 89/5/623    most recent expphysiol.2004.027706v1 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 Google Scholar Google Scholar Articles by Bazán-Perkins, B. Articles by Montaño, L. M. Search for Related Content PubMed PubMed Citation Articles by Bazán-Perkins, B. Articles by Montaño, L. M. Related Collections Respiratory

¹ Departamento de Investigación en Hiperreactividad Bronquial, Instituto Nacional de Enfermedades Respiratorias, Tlalpan 4502, CP 14080, México DF, México² Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, CP 04510, México DF, México

Barometric plethysmography for unrestrained animals is a non-invasive method that allows repetitive measurements of pulmonary function, but habituation of the conscious animal to this technique has not been explored. Respiratory frequency (f_R) and ‘enhanced pause’ (P_enh) were measured by barometric plethysmography for a period of 8 h in guinea-pigs. Compared with basal values, during the first hour of recording a progressive increase in P_enh (up to 25–50%) and a corresponding decrease in f_R were recorded, followed by a relative plateau in each for up to 8 h. These changes were avoided by a 30-min pretreatment with propranolol and L-NAME (nitric oxide synthase inhibitor), with P_enh values as high as this plateau phase since the beginning of recording. Atropine, salbutamol or budesonide did not modify the progressive increment in P_enh. We concluded that catecholamines and nitric oxide are released when guinea-pigs are introduced into the plethysmographic chamber, leading to initial low P_enh values. These mediators probably diminish owing to habituation of the animal to the new environment, with an apparent progressive increment in P_enh. These spontaneous changes in P_enh and f_R must be taken into account during barometric plethysmography in order to avoid misinterpretation of the results.

(Received 25 March 2004; accepted after revision 8 July 2004; first published online 15 July 2004)
Corresponding author M. H. Vargas: Departamento de Investigación en Hiperreactividad Bronquial, Instituto Nacional de Enfermedades Respiratorias, Tlalpan 4502, CP 14080, México DF, México. Email: mhvargasb{at}yahoo.com.mx