Inhibitory effects of propiverine on rat and guinea-pig urinary bladder muscle

In muscle strips isolated from guinea-pig and rat urinary bladder, propiverine (3-10 microM) inhibited carbachol-induced contractions in the presence of verapamil and Ca(2+)-induced contractions in excess K+ medium containing atropine, suggesting it has both anticholinergic and Ca2+ channel blocking actions. The Ca2+ channel blocking action was also demonstrated by recording inward Ca2+ currents in single cells dispersed from both species. The inhibition of inward currents by propiverine was three times stronger in the rat than the guinea-pig, ID50 being 7 microM for rat and 21 microM for guinea-pig. The recovery of the current after washout was faster than that of mechanical inhibition. It is concluded that propiverine blocks not only muscarinic receptors, but also Ca2+ channels at similar concentrations.