A voltage-independent K+ conductance activated by cell swelling in Ehrlich cells is modulated by a G-protein-mediated process.
Cell swelling following hypoosmotic stress leads to the activation of volume-sensitive ion channels that allow a K+ and Cl- efflux accompanied by water loss. A Ca2+-insensitive K+ channel (I(K,vol)) has been described in Ehrlich cells that can be activated by hypotonicity and leukotriene D4 and is inhibited by clofilium. We have studied the activation and deactivation by osmotic stimuli of this channel. A G-protein appears to be involved in these processes since GTP-gamma-S accelerates deactivation, while GDP-beta-S blocks the channel in the open state, a result mimicked by pertussis toxin (PTX). In addition, PTX accelerates the onset of I(K,vol). We propose that I(K,vol) is tonically inhibited by a PTX-sensitive G-protein.
Niemeyer
María Isabel
MI
Centro de Estudios Científicos (CECS), Valdivia, Chile. miniemeyer@cecs.cl
Stutzin
Andrés
A
Sepúlveda
Francisco V
FV
D000818:Animals; D002286:Carcinoma, Ehrlich Tumor; D002412:Cations / Q000737:chemistry; D048429:Cell Size; D002712:Chlorides / Q000737:chemistry*; D004533:Egtazic Acid; D004553:Electric Conductivity; D019204:GTP-Binding Proteins / Q000737:chemistry*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D007038:Hypotonic Solutions; D007473:Ion Channels / Q000737:chemistry* / Q000187:drug effects; D051379:Mice; D037342:Pertussis Toxin; D011188:Potassium / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D002412:Cations; D002712:Chlorides; D007038:Hypotonic Solutions; D007473:Ion Channels; D000644:Quaternary Ammonium Compounds; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D006153:Guanosine Diphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D004533:Egtazic Acid; C023427:guanosine 5'-O-(2-thiodiphosphate); C022799:clofilium; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D011188:Potassium