RANTES and platelet-activating factor open Ca2+-activated K+ channels in eosinophils.
RANTES is a member of the low molecular cytokines and appears to be strictly a chemotactic and activating factor for eosinophils. We studied the effect of RANTES on the channel activity of the eosinophilic cell line (EoL-1 cells) using patch clamp techniques. Under cell-attached patch conditions, RANTES (20 ng/ml) activated channels in EoL-1 cells when applied to the recording pipette or to the bath. This channel was permeable to K+ with a unit conductance of 14 pS, and the reversal potential was close to the equilibrium potential for K+. The current-voltage relationship for this K+ channel was almost linear, showing little or no rectification. The open time and closed time histograms could he fitted to a single exponential function with time constants of 6.4 and 2.7 ms, respectively. Extracellular application of the calcium ionophore A23187 (1 microM) under cell-attached patch conditions or an increase in intracellular Ca2+ concentration under inside-out patch conditions increased K+ channel activity in a manner similar to that caused by RANTES, indicating that the RANTES-activated channel was the Ca2+ -activated K+ channel. Intracellular application of GTP gamma S (10 microM) opened the Ca2+V-activated K+ channels under inside-out patch conditions. Furthermore, RANTES failed to activate the K+ channels after the cells had been treated with pertussis toxin (100 ng/ml) for 2 h at 37 degrees C. These results suggest that RANTES opens the Ca2+ -activated K+ channels of EoL-1 cells through activation of G-proteins.
Saito
M
M
Department of Molecular Pharamacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60611-3008, USA.
Sato
R
R
Hisatome
I
I
Narahashi
T
T
D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D018946:Chemokine CCL5 / Q000502:physiology*; D004804:Eosinophils / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D010972:Platelet Activating Factor / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology*
D018946:Chemokine CCL5; D010972:Platelet Activating Factor; D015221:Potassium Channels; D019204:GTP-Binding Proteins; D002118:Calcium