Flux of 86Rb in activated human lymphocytes

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Abstract
Preparations of human peripheral blood lymphocytes were preloaded with 86Rb+ after which efflux of the radioisotope, a congener of K, was determined by spinning unwashed cells for 15 s through a nonaqueous solvent and then counting the pellet. Stimulation by phytohemagglutinin caused rapid increase in efflux, noticeable within 15 min of addition of mitogen. Efflux from control and stimulated cells was not affected by ouabain at a concentration which completely inhibited blastogenesis. Mean rates of cation exit rose from 4.2 .+-. 0.7 fmol[femtomoles]/cell per h to 9.9 .+-. 1.3 fmol/cell per h following stimulation by mitogen. The previously reported increase in influx of K+ into stimulated cells is balanced by an increase in the rate at which this ion and its congener 86Rb+ leak out, resulting in a constant concentration of K+ during initial activation, as reported by Segel and Lichtman. To determine whether efflux changed during actual volume change of blast formation, rates of 86Rb exit from preloaded cells were compared after 0.24 and 48 h incubation in presence of mitogen. Significant changes were not noted. While evidence of an increase in the ratio of influx:efflux was not found, either such a change does occur or there must be a large decrease in the K+ concentration within the cell water during blast formation.

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