A forskolin and verapamil sensitive K+ current in human tracheal cells.
A voltage-dependent K+ current has been revealed in whole-cell recordings carried out on immortalized cells obtained from the human tracheal epithelium. At positive membrane potentials the current shows a time dependent inactivation which is accelerated by increasing the depolarizing step. Forskolin, a direct activator of adenylyl cyclase, and verapamil, a Ca2+ channel blocker, induce the K+ current to inactivate more rapidly. Control experiments show that the action of these two compounds is not mediated by cyclic AMP and Ca2+. The application of 1,9-dideoxyforskolin, an analogue which does not stimulate adenylate cyclase, inhibits the current in the same way as forskolin; on the contrary, the dibutyryl analogue of cyclic AMP is ineffective. Furthermore, eliminating extracellular Ca2+ does not affect K+ current kinetics. Tetraethylammonium is an effective blocker of this current with an IC50 of 0.3 mM.
Laboratorio di Genetica Molecolare, Istituto Giannina Gaslini, Genova, Italy.
L J
LJ
Galietta
A
A
Rasola
V
V
Barone
D C
DC
Gruenert
G
G
Romeo
D002460:Cell Line; D005576:Colforsin / Q000031:analogs & derivatives / Q000494:pharmacology*; D004848:Epithelium; D006801:Humans; D006982:Hypertonic Solutions; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D014132:Trachea; D014700:Verapamil / Q000494:pharmacology*
D006982:Hypertonic Solutions; D015221:Potassium Channels; D005576:Colforsin; D014700:Verapamil