['Although procaterol is used clinically as a beta(2)-adrenergic receptor agonist to relax airway smooth muscle, it has not yet been clarified whether procaterol has inotropic effects on respiratory muscles.', '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.', '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.'] Does inhalation and incubation with procaterol increase diaphragm muscle contractility in mice?