INHIBITORY EFFECTS OF PROPIVERINE ON RAT AND GUINEA-PIG URINARY-BLADDER MUSCLE

In muscle strips isolated from guinea-pig and mt urinary bladder, prop iverine (3 - 10 muM) inhibited carbachol-induced contractions in the p resence of verapamil and Ca2+-induced contractions in excess K+ medium containing atropine, suggesting it has both anticholinergic and Ca2channel blocking actions. The Ca2+ channel blocking action was also de monstrated by recording inward Ca2+ currents in single cells dispersed from both species. The inhibition of inward currents by propiverine w as three times stronger in the rat than the guinea-pig, ID50 being 7 m uM for rat and 21 muM for guinea-pig. The recovery of the current afte r washout was faster than that of mechanical inhibition. It is conclud ed that propiverine blocks not only muscarinic receptors, but also Ca2 + channels at similar concentrations.