PLASMA-MEMBRANE STUDIES ON DRUG SENSITIVE AND RESISTANT CELL-LINES .4. RUBIDIUM TRANSPORT AND OUABAIN BINDING

A comparison of the K+ pump sensitivity to ouabain inhibition has been made between ouabain-resistant cells and their wild-type counterparts and between oncogenic and non-oncogenic cell lines; all of them being derived from the murine plasmocytoma MOPC 173. In both instances a common mechanism of resistance might be involved: in resistant cell lines the Na+ K+ pump is less stimulated by a drop of [K+]i or an increase in [K+]0 than in susceptible cell lines. Moreover the apparent affinity for ouabain diminished far more in resistant than in susceptible cell lines both when [K+]0 increased and when [K+]i decreased. © 1979.