Potassium channel KVα1 subunit expression and function in human detrusor muscle

Purpose: We determined whether voltage gated K+ (K-V) channels are expressed and functional in human detrusor smooth muscle. Materials and Methods: Information on K-V channels was obtained using electrophysiological patch clamp, immunofluorescence, Western blot and isometric tension recording techniques. Results: Patch clamp recordings from detrusor cells revealed a Ca2+ independent K+ current that was activated by depolarization in a voltage range near the resting potential of detrusor smooth muscle. The current was inhibited by 3,4-diaminopyridine, a blocker of K-V channels. Antibodies targeted to K(V)alpha1 subunits revealed K(V)1.3 and K(V)1.6 expression in whole bladder tissue samples and specifically in detrusor smooth muscle cells. New specific blockers of K(V)alpha1 channel currents (correolide and recombinant agitoxin-2) had a myogenic effect, characterized by increased amplitude of spontaneous contractions without an effect on the frequency of contractions or on resting baseline tension. Conclusions: K(V)alpha1 subunits are expressed and functionally important in human detrusor muscle.