Inwardly rectifying K+ channels and volume-regulated anion channels in multidrug-resistant small cell lung cancer cells.
Studies of multidrug-resistant H69AR cells which overexpress the multidrug resistance-associated protein, compared with drug-sensitive parental H69 cells and revertant H69PR cells, revealed an inwardly rectifying K+ channel current (conductance, 231 pS/pF) and increased volume-regulated anion current (limiting conductance, 2 nS/pF). The anion current was selective for Cl- ions and sensitive to 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (0.1-1 mM) but ATP was not required for initial current activation even in excised patch experiments. K+ current reversal potential varied 52 mV/10-fold change in the external K+ concentration and current was blocked by BaCl2 (0.1-1 mM). The results indicate that overexpression of multidrug resistance-associated protein is accompanied by increases in both K+ channel and volume-regulated Cl- channel current in the multidrug-resistant cell line H69AR.
Department of Physiology, Queen's University, Kingston, Canada.
J
J
Jirsch
R G
RG
Deeley
S P
SP
Cole
A J
AJ
Stewart
D
D
Fedida
D018288:Carcinoma, Small Cell / Q000378:metabolism*; D018118:Chloride Channels; D004351:Drug Resistance; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism*; D008565:Membrane Proteins / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology*; D014407:Tumor Cells, Cultured
D018118:Chloride Channels; D008565:Membrane Proteins; D015221:Potassium Channels