Premium
EFFECT OF SERUM ON SODIUM PUMP ACTIVITY AT VARIOUS CONCENTRATIONS OF INTERNAL AND EXTERNAL SODIUM IN MOUSE (3T3) AND HUMAN ( HeLa ) CELLS
Author(s) -
Lamb J. F.,
Ogden P.,
Singh J.
Publication year - 1986
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1986.sp002996
Subject(s) - sodium , ouabain , hela , chemistry , intracellular , stimulation , saturation (graph theory) , 3t3 cells , incubation , biophysics , endocrinology , cell , biochemistry , biology , transfection , mathematics , organic chemistry , combinatorics , gene
Serum causes a large rise in the ouabain‐sensitive K influx in 3T3 and other cells. It has been argued that this is secondary to the increased Na and K leaks which are also caused by serum. We have measured the K influx into 3T3 and HeLa cells at various values of intracellular Na concentration ([Na] i ), and from Na‐free medium in 1 and 20% (v/v) serum. Raising [Na] i increases the K influx, but saturation does not occur over the range of [Na] i studied. The estimated K m for [Na] i is around 130 mM and the V max some 10 times that of the resting K influx at normal (20 mM) [Na] i . Serum stimulates the K influx by a constant proportion at all values of [Na] i studied, and in Na‐free medium. These results are inconsistent with previous explanations of the serum stimulation of pumping.