High-conductance chloride channels generate pacemaker currents in interstitial cells of Cajal.

Background & Aims: Interstitial cells of Cajal (ICCs) are responsible for slow, wave-driven, rhythmic, peristaltic motor patterns in the gastrointestinal tract. The aim was to identify and characterize the ion channels that generate the underlying pacemaker activity.

Methods: Single ion channel recordings were obtained from nonenzymatically isolated ICCs and studied by using the cell attached and inside-out configurations of the patch clamp technique.

Results: A high-conductance chloride channel was observed in ICCs that was spontaneously and rhythmically active at the same frequency as the rhythmic inward currents defining ICC pacemaker activity, 20-30 cycles/min at room temperature. Main conductance levels occurred between 122-144 pS and between 185-216 pS. Periodicity in the channel opening coincided with periodicity in membrane potential change, hence, at the single channel level, chloride channels were seen to be associated with the generation of rhythmic changes in membrane potential.

Conclusions: ICCs harbor high-conductance chloride channels that participate in the generation of pacemaker activity and may become a target for pharmacologic treatment of gut motor disorders.