Erythroid differentiation and the Na+,K+-pump in ouabain-sensitive and ouabain-resistant Friend erythroleukemia cell lines.
The selection and biochemical characterization of ouabain-resistant erythroleukemia cell lines are described. Treatment of ouabain-resistant Friend erythroleukemia cell (FLC) lines with 1 mM ouabain demonstrated a reduced ouabain-sensitive 86Rb+-uptake after Na+-preloading in comparison with ouabain-sensitive cells. The ouabain- and diuretic (piretanide)-insensitive component of the 86Rb+-uptake (residual influx) was significantly enhanced in the ouabain-resistant FLC clones. Measurements of the Na+,K+-ATPase activity (E.C. 3.6.1.3) in plasma membrane preparations of the ouabain-resistant FLC clone B6/2 indicated that a ouabain-resistant Na+,K+-ATPase activity of about 20% of the total enzyme activity existed in the presence of 1 mM ouabain. Further experiments showed that the Na+,K+-ion-gradient in ouabain-resistant B6/2 cells was unaffected by ouabain exposure whereas the gradient collapsed in wild type 12 N cells. Another property of the ouabain-resistant cell lines was a decrease of the 86Rb+-uptake due to the Na+,K+, 2Cl(-)-cotransport system measured as piretanide-sensitive 86Rb+-uptake. The data on ion transport mechanisms in QuaR and QuaS FLC are discussed with respect to mutagen-induced and spontaneous cellular ouabain resistance. In addition, the role of altered ion transport mechanisms is considered for induced erythroid differentiation.
Munter
K H
KH
Steinheider
G
G
Schaefer
A
A
Koch
G
G
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D004912:Erythrocytes / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D007473:Ion Channels / Q000032:analysis / Q000378:metabolism*; D004915:Leukemia, Erythroblastic, Acute / Q000473:pathology*; D051379:Mice; D010042:Ouabain / Q000494:pharmacology*; D011868:Radioisotopes; D012413:Rubidium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood
D007473:Ion Channels; D011868:Radioisotopes; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium