A schematic summary of this study. Dimethyl sulfoxide (DMSO) strongly inhibits acetylcholinesterase (AChE) activities. This inhibition leads to suppress the degradation of acetylcholine (ACh) released from parasympathetic nerve in micturition, and thus increase the amount of ACh around urinary bladder smooth muscle (UBSM). The increased ACh becomes more likely to activate UBSM acetylcholine receptors, thereby enhancing UBSM contractions. DMSO also inhibits UBSM contractile intracellular signaling, but the enhancing effect on UBSM contractions through AChE inhibition is stronger than this inhibitory effect.