Cell growth and quabain-sensitive 86Rg+ uptake and (Na++K+)-ATPase activity in 3T3 and SV40 transformed 3T3 fibroblasts.

The uptake of ouabain-sensitive 86Rb+ uptake measured at 5 min and the uptake measured at 60 min was 4.5- and 2.7-fold greater respectively for SV40 transformed 3T3 cells compared to 3T3 cells during the late log phase of growth. This uptake, however, varied markedly with cell growth. Ouabain-sensitive 86Rb+ uptake was found to be a sensitive indicator of protein synthesis as measured by total protein content. Cessation of cell growth as measured by total protein content was associated with a decline in ouabain-sensitive 86Rb+ uptake in both cell types. This increase ouabain-sensitive cation transport was reflected in increased levels of (Na++K)-ATPase activity for SV40 3T3 cells, which showed a 2.5-fold increase V but the same Km as 3T3 cells. These results are compared with the results of related work. Possible mechanisms for these effects are discussed and how changes in cation transport might be related to alterations in cell growth.