Are alpha-adrenergic antagonists potent tocolytics? In vivo experiments on postpartum rats

The aim of this study was to investigate the effects of alpha-adrenergic antagonists on the motor activity of the postpartum uterus of the rat in vivo. Intrauterine pressure was assessed by means of a Millar catheter fitted with a latex microballoon. Some of the tested compounds (urapidil, yohimbine, phentolamine, benoxathian and prazosin) decreased the uterine activity to a significant extent (57.4-67.4%). However, none of the investigated alpha receptor blockers exerted the same effect as beta-adrenergic agonists. Our results suggest that alpha-adrenergic antagonists could possibly be used as an alternative to beta-adrenergic agonists in clinical tocolysis after an appropriate clinical evaluation.