Excitatory effect of propiverine hydrochloride on urethral activity in rats

Objectives: To investigate the effects of the antimuscarinic agent, propiverine, on the bladder and urethra in rats. Methods: A total of 54 female rats were given propiverine, imidafenacin (an antimuscarinic agent), or distilled water by gavage once or twice daily. After 2 weeks, bladder and urethral activity were recorded under urethane anesthesia. In the propiverine group, the changes of bladder and urethral activity before and after intravenous injection of α1‐adrenergic antagonists (prazosin, silodosin and naftopidil) were also recorded. Furthermore, the leak point pressure after electrical stimulation of abdominal wall muscles was measured in rats with vaginal distension from the control and propiverine groups. Results: Intravesical baseline pressure was significantly lower in the propiverine and imidafenacin groups compared with the control group, whereas the urethral baseline pressure was significantly higher in the propiverine group compared with the control or imidafenacin groups. Intravenous injection of prazosin (an α1‐receptor antagonist) significantly decreased the urethral baseline pressure in both of the propiverine and control groups. Intravenous injection of silodosin and naftopidil (α1A‐ and α1D‐receptor antagonists, respectively) significantly decreased the maximum contraction pressure and the urethral baseline pressure in the propiverine group. The leak point pressure of the propiverine group was significantly higher than that of the control group. Conclusions: An increase of catecholamines after propiverine administration might activate smooth muscle of the proximal urethra via α1A‐ and α1D‐adrenergic receptors, as well as activating urethral and pelvic floor striated muscle via the spinal motoneurons.