title: The effect of lanthanum on electrophoretic mobility and passive cation movements of the Ehrlich ascites tumor cell.
abstract: We have investigated the effects of La+3 binding to the surface of Ehrlich ascites tumor cells on cell electrophoretic mobility and passive movements of Na+ and K+. Incubation of tumor cells in La+3-containing media results in a La+3 concentration-dependent decrease in net surface charge negativity. At [La+3] greater than 0.5 mM, the net surface charge becomes positive with maximum positivity occurring at [La+3] = 0.9 mM. The effects of La+3 binding on passive Na+ and K+ movements were investigated by following 22Na and K+ losses from ouabain-inhibited cells. Neither low (0.02) nor high (1.0 mM) [La+3] had any effect on the K+ efflux rate coefficient. 22Na losses from control and La+3-treated cells were consistent with washouts from two cellular compartments. Low [La+3] (0.02 mM) was without effect on Na+ losses from the cells. However, higher [La+3] (1.0 mM) resulted in a 48% inhibition of Na+ loss from the more slowly exchanging compartment. These results are not consistent with simple electrostatic interactions exerting a major influence on the passive movements of Na+ and K+. It is suggested that La+3 interacts with sites specific for Na+, perhaps involved in a carrier-mediated exchange system.
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004586:Electrophoresis; D007811:Lanthanum / Q000378:metabolism / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects*; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
chemical_list: D007811:Lanthanum; D012964:Sodium; D011188:Potassium