Depletion of intracellular calcium stores activates an outward potassium current in mast and RBL-1 cells that is correlated with CRAC channel activation.
Highly Ca2+ selective Ca2+ channels activated by store depletion have been recently described in several cell types and have been termed CRAC channels (for calcium release-activated calcium). The present study shows that following store depletion in mast and RBL-1 cells, monovalent outward currents could be recorded if the internal solution contained K+ but not Cs+. The activation of the outward K+ current correlated with the activation of ICRAC, in both time and amplitude, suggesting that the K+ current might be carried by CRAC channels. The amplitude of the outward current was increased if external Ca2+ was reduced or replaced by external Ba2+. The outward K+ conductance might have a physiological role in maintaining the driving force for Ca2+ entry during the activation of CRAC channels.
Hoth
M
M
Department of Membrane Biophysics, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany. mhoth@leland.stanford.edu
D000818:Animals; D001464:Barium / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D002586:Cesium / Q000378:metabolism; D008407:Mast Cells / Q000378:metabolism*; D008564:Membrane Potentials; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D014407:Tumor Cells, Cultured
D015220:Calcium Channels; D002586:Cesium; D001464:Barium; D011188:Potassium; D002118:Calcium