Inhalation and Incubation with Procaterol Increases Diaphragm Muscle Contractility in Mice

ABSTRACTBackgroundAlthough procaterol is used clinically as a β2-adrenergic receptor agonist to relax airway smooth muscle, it has not yet been clarified whether procaterol has inotropic effects on respiratory muscles.MethodsThree intervention groups were investigated: a procaterol inhalation only group; a procaterol inhalation plus endotoxin injection group (in vivo); and a procaterol incubation group (in vitro). The diaphragm muscle in all groups was dissected and measurements of its contractile properties were performed.ResultsThe effects of procaterol inhalation shifted the force-frequency curves upward at 30 minutes after inhalation, and inhibited the decline of force-frequency curves due to endotoxin injection in vivo. In vitro administration of procaterol resulted in an increase in the force-frequency curves in a dose-dependent manner.ConclusionsIt can be concluded that procaterol has an inotropic effect on the diaphragmatic muscles taken from normal animals as well as on the diaphragm muscles in a septic animal model.