In vitro effects of β3-adrenoceptor agonist mirabegron on the human ureter.

INTRODUCTION: This study aimed to investigate the effect of mirabegron, a β3-adrenoceptor agonist with widespread clinical use for treating overactive bladder disease, on isolated healthy human ureter strips.

MATERIALS AND METHODS: This was a prospective study employing a series of in vitro organ bath experiments using ureteral tissues of kidney grafts from 10 healthy donors. The ureteral strips were subjected to cumulative mirabegron concentrations (10-9 -10-4.5  M). Effects on frequency or amplitude of spontaneous, 10 mM KCl- or EFS-induced contractions were evaluated.

RESULTS: Mirabegron decreased the frequency of spontaneous ureteric contraction in a concentration-dependent manner. Statistically significant decrease in the frequency of spontaneous contraction was observed at 10-8 -10-4.5  M. In 10 mM KCl medium, statistically significant change in frequency was observed at 10-9 -10-4.5  M. Statistically significant decrease in the amplitudes of spontaneous contraction was observed at 10-7 -10-4.5  M. In a 10 mM KCl medium, statistically significant change in amplitudes was observed at 10-8 -10-4.5  M.

CONCLUSIONS: Mirabegron reduced the amplitude and frequency of human ureter activity in in vitro organ bath studies. This effect was achieved in a dose-dependent manner on isolated tissue strips. Although monotherapy with mirabegron remains uncertain, this study has the potential to elucidate the mechanism underlying the effectiveness of mirabegron, particularly in combination therapy for ureteral stones.