Novel mechanism of hydrogen sulfide - induced guinea pig urinary bladder smooth 1 muscle contraction : The role of BK channels and cholinergic neurotransmission

26 Hydrogen sulfide (H 2 S) is a key signalling molecule regulating important physiological 27 processes, including smooth muscle function. However, the mechanisms underlying H 2 S-28 induced detrusor smooth muscle (DSM) contractions are not well understood. This study 29 investigates the cellular and tissue mechanisms by which H 2 S regulates DSM contractility, 30 excitatory neurotransmission, and large-conductance voltage-and Ca 2+-activated K + (BK) 31 channels in freshly-isolated guinea pig DSM. We used a multidisciplinary experimental 32 approach including isometric DSM tension recordings, colorimetric ACh measurement, Ca 2+ 33 imaging, and patch-clamp electrophysiology. In isolated DSM strips, the novel slow release 34