The aim of the present study is to characterize voltage-sensitive macroscopic K+ current (IK) components in freshly isolated @entity1 colonic smooth muscle cells. IK components were studied by the conventional whole-cell voltage clamp method. We found two main components of IK. A transient IK component with fast kinetics, IK(fi), activated upon a holding potential of Vh = -80 mV and inactivated completely following a 4-second-long prepulse to 0 mV. IK(fi) was abolished by Vh = -50 mV, as well as by a pipette solution containing 11 mM @entity4527 . The second, non-inactivating IK component, IK(ni), had comparable amplitudes at Vh = -80 mV and Vh = -50 mV and could not be inactivated completely, even by positive conditioning stimuli. The amplitudes of IK(ni) depended strongly on the @entity141 entry, while the amplitudes and the time course of IK(fi) were modulated mainly by the intracellular @entity141 concentration. About 80% of IK(ni) was selectively inhibited by 0.5 microM apamin. IK(fi) was insensitive to apamin and was totally abolished by 20 mM @entity5128 extracellularly. According to their voltage dependencies, inactivation properties and pharmacological sensitivity to various K+ channels antagonists, these IK components differ from those described in colonic smooth muscle cells of laboratory animals.

Main components of voltage-sensitive K+ currents of the XXXX colonic smooth muscle cells.

@entity1 :: ('9606', 'Species') :: ['human'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca2+'] @entity4527 :: ('MESH:D004533', 'Chemical') :: ['EGTA'] @entity5128 :: ('MESH:D019789', 'Chemical') :: ['tetraethyl ammonium']
@entity1 :: (9606,Species) :: ['human']
