Calcium-Dependent K-Channels in Guinea Pig and Human Urinary Bladder

Abstract

This study provides evidence for the presence of large conductance Ca2+-dependent K-channels in guinea pig and human urinary bladder smooth muscle. A23187, a Ca2+-ionophore, increased charybdotoxin and iberiatoxin sensitive 42K efflux in human urinary bladder smooth muscle cells, suggesting that large conductance Ca2+-dependent K-channels are present in these cells. NS004, a large conductance Ca2+-dependent K-channel opener, relaxed guinea pig bladder strips precontracted with 15 mM KCl which is inhibited by iberiatoxin. In addition, NS004 also evoked an iberiatoxin sensitive increase in 86Rb/42K efflux in guinea pig and human urinary bladder smooth muscle cells, demonstrating that NS004 activates large conductance Ca2+-dependent K-channels to achieve its relaxation effect in the bladder.