Inhalation and incubation with procaterol increases diaphragm muscle contractility in mice

Background: Although 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. Methods: Three 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. Results: The 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. Conclusions: It 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.