Abstract
We examined the effects of methyl-β-cyclodextrin (MβCD) on Ca2+-induced Ca2+ release (CICR) in smooth muscle cells (SMCs) of mouse urinary bladder (UB). Short depolarization of UBSMCs under voltage-clamp elicited several local Ca2+ transients (Ca2+ hot spots) via CICR within 20 ms in discrete sub-sarcolemmal areas. Then, the Ca2+ wave spread to whole areas. The pretreatment with 10 mM MβCD significantly attenuated Ca2+ hot spots in UBSMCs and reduced contraction by single direct electrical pulse stimulation in UBSM strips. MβCD may prevent CICR by attenuating the coupling between voltage-dependent Ca2+ channels and ryanodine receptors in Ca2+ hot spot areas.
