KCNQ Currents and Their Contribution to Resting Membrane Potential and the Excitability of Interstitial Cells of Cajal From the Guinea Pig Bladder

Purpose: The presence of novel KCNQ currents was investigated in guinea pig bladder interstitial cells of Cajal and their contribution to the maintenance of the resting membrane potential was assessed.Materials and Methods: Enzymatically dispersed interstitial cells of Cajal were patch clamped with K+ filled pipettes in voltage clamp and current clamp modes. Pharmacological modulators of KCNQ channels were tested on membrane currents and the resting membrane potential.Results: Cells were stepped from −60 to 40 mV to evoke voltage dependent currents using a modified K+ pipette solution containing ethylene glycol tetraacetic acid (5 mM) and adenosine triphosphate (3 mM) to eliminate large conductance Ca activated K channel and Kadenosine triphosphate currents. Application of the KCNQ blockers XE991, linopirdine (Tocris Bioscience, Ellisville, Missouri) and chromanol 293B (Sigma®) decreased the outward current in concentration dependent fashion. The current-voltage relationship of XE991 sensitive current rev...