Methyl-beta-cyclodextrin prevents Ca2+-induced Ca2+ release in smooth muscle cells of mouse urinary bladder

We examined the effects of methyl-beta-cyclodextrin (MbetaCD) on Ca(2+)-induced Ca(2+) release (CICR) in smooth muscle cells (SMCs) of mouse urinary bladder (UB). Short depolarization of UBSMCs under voltage-clamp elicited several local Ca(2+) transients (Ca(2+) hot spots) via CICR within 20 ms in discrete sub-sarcolemmal areas. Then, the Ca(2+) wave spread to whole areas. The pretreatment with 10 mM MbetaCD significantly attenuated Ca(2+) hot spots in UBSMCs and reduced contraction by single direct electrical pulse stimulation in UBSM strips. MbetaCD may prevent CICR by attenuating the coupling between voltage-dependent Ca(2+) channels and ryanodine receptors in Ca(2+) hot spot areas.