Maxi K+ channel mediates regulatory volume decrease response in a human bronchial epithelial cell line.
The cell regulatory volume decrease (RVD) response triggered by hypotonic solutions is mainly achieved by the coordinated activity of Cl- and K+ channels. We now describe the molecular nature of the K(+) channels involved in the RVD response of the human bronchial epithelial (HBE) cell line 16HBE14o-. These cells, under isotonic conditions, present a K+ current consistent with the activity of maxi K+ channels, confirmed by RT-PCR and Western blot. Single-channel and whole cell maxi K+ currents were readily and reversibly activated following the exposure of HBE cells to a 28% hypotonic solution. Both maxi K+ current activation and RVD response showed calcium dependency, inhibition by TEA, Ba2+, iberiotoxin, and the cationic channel blocker Gd3+ but were insensitive to clofilium, clotrimazole, and apamin. The presence of the recently cloned swelling-activated, Gd3+-sensitive cation channels (TRPV4, also known as OTRPC4, TRP12, or VR-OAC) was detected by RT-PCR in HBE cells. This channel, TRPV4, which senses changes in volume, might provide the pathway for Ca2+ influx under hypotonic solutions and, consequently, for the activation of maxi K+ channels.
Fernández-Fernández
José M
JM
Unitat de Senyalització Cellular, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, 08003 Barcelona, Spain.
Nobles
Muriel
M
Currid
Aoife
A
Vázquez
Esther
E
Valverde
Miguel A
MA
D001980:Bronchi / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D002460:Cell Line; D004553:Electric Conductivity; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007038:Hypotonic Solutions / Q000494:pharmacology; D051036:Large-Conductance Calcium-Activated Potassium Channels; D024681:Potassium Channels, Calcium-Activated / Q000502:physiology*
D007038:Hypotonic Solutions; D051036:Large-Conductance Calcium-Activated Potassium Channels; D024681:Potassium Channels, Calcium-Activated