title: Broxaterol increases force output of fatigued canine diaphragm more than salbutamol.
abstract: We previously demonstrated that broxaterol enhanced recovery of fatigued canine diaphragm. The aim of this study was to compare the inotropic effects of salbutamol and broxaterol on fatigued canine diaphragm. Low-frequency fatigue was induced in 14 mongrel dogs by electrophrenic stimulation, which was continued until transdiaphragmatic pressure (Pdi) at 20 Hz was reduced by 50% or for 1 h. After stabilization of fatigue, the animals received a bolus (18.5 microg/kg) of either broxaterol or salbutamol, followed by a continuous infusion (0.43 microg/kg/min). A second bolus of 74.0 microg/kg, followed by a continuous infusion of 1.72 microg/kg/min, was given after 90 min. Both drugs significantly increased twitch Pdi. Twitch Pdi measured 90 min after the first and second doses of broxaterol increased by 28 +/- 23% and 42 +/- 34%, respectively, whereas the salbutamol-induced increase was clearly smaller (9 +/- 10% and 17 +/- 15%, respectively). Broxaterol increased Pdi at 20 Hz by 25 +/- 28% with the first dose and by 29 +/- 21% with the second dose. In contrast, salbutamol did not alter Pdi at 20 Hz. Neither drug affected Pdi at 100 Hz. We conclude that broxaterol promoted recovery of low-frequency fatigue of the canine diaphragm in vivo in a dose-dependent manner, whereas salbutamol only minimally improved force production by the fatigued diaphragm.
authors.affiliation: Respiratory Muscle Research Unit, Laboratory of Pneumology, Katholieke Universiteit Leuven, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Derom
authors.forename: G
authors.initials: G
authors.lastname: Gayan-Ramirez
authors.forename: G
authors.initials: G
authors.lastname: Gurrieri
authors.forename: V
authors.initials: V
authors.lastname: de Bock
authors.forename: M
authors.initials: M
authors.lastname: Decramer
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000420:Albuterol / Q000494:pharmacology*; D000818:Animals; D003964:Diaphragm / Q000187:drug effects* / Q000502:physiology; D004285:Dogs; D007555:Isoxazoles / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D018763:Muscle Fatigue / Q000187:drug effects*
chemical_list: D000318:Adrenergic beta-Agonists; D007555:Isoxazoles; D000420:Albuterol; C045916:broxaterol