Big-conductance Ca2+-activated K+channels in physiological and pathophysiological urinary bladder smooth muscle cells.
Contraction and relaxation of urinary bladder smooth muscle cells (UBSMCs) represent the important physiological functions of the bladder. Contractile responses in UBSMCs are regulated by a number of ion channels including big-conductance Ca2+- activated K+(BK) channels. Great progress has been made in studies of BK channels in UBSMCs. The intent of this review is to summarize recent exciting findings with respect to the functional interactions of BK channels with muscarinic receptors, ryanodine receptors (RyRs) and inositol triphosphate receptors (IP3Rs) as well as their functional importance under normal and pathophysiological conditions. BK channels are highly expressed in UBSMCs. Activation of muscarinic M3receptors inhibits the BK channel activity, facilitates opening of voltage-dependent Ca2+(CaV) channels, and thereby enhances excitability and contractility of UBSMCs. Signaling molecules and regulatory mechanisms involving RyRs and IP3Rs have a significant effect on functions of BK channels and thereby regulate cellular responses in UBSMCs under normal and pathophysiological conditions including overactive bladders. Moreover, BK channels may represent a novel target for the treatment of bladder dysfunctions.
a Center for Cardiovascular Sciences, Albany Medical College , Albany , NY , USA.
Shankar P
SP
Parajuli
a Center for Cardiovascular Sciences, Albany Medical College , Albany , NY , USA.
Yun-Min
YM
Zheng
b Stratton VA Medical Center , Albany , NY , USA.
Robert
R
Levin
a Center for Cardiovascular Sciences, Albany Medical College , Albany , NY , USA.
Yong-Xiao
YX
Wang
D000818:Animals; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000502:physiology; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000502:physiology; D019837:Ryanodine Receptor Calcium Release Channel / Q000502:physiology; D001743:Urinary Bladder / Q000502:physiology* / Q000503:physiopathology
D053496:Inositol 1,4,5-Trisphosphate Receptors; D051036:Large-Conductance Calcium-Activated Potassium Channels; D011976:Receptors, Muscarinic; D019837:Ryanodine Receptor Calcium Release Channel
big-conductance Ca2+-activated K+ channel; inositol triphosphate receptor; muscarinic receptor; overactive bladder; ryanodine receptor; urinary bladder smooth muscle cell