PubMed1984
The paper is concerned with a study of the molecular mechanisms responsible for activation of B lymphocyte division by polyanions, polyacrylic acid (PAA) and dextran sulfate (DS). The mitogenic doses of PAA and DS were discovered to provoke an early increase in lymphocyte plasma membrane permeability. The cell membrane permeability for K+, Ca2+ and for labeled thymidine and uridine was measured in murine spleen cultures in vitro The K+ outflow from the cells was recorded according to variation in K+ concentration in the extracellular medium with the aid of a selective valinomycin electrode. The intensity of cell penetration by exogenous 45Ca, 3H-uridine or 3H-thymidine was determined by radioindicator analysis of the cytoplasma isotope pool. One to 2 min after adding the mitogenic doses of PAA or DS, the K+ outflow from lymphocytes markedly increased. It has been proved that this effect is not connected with inhibition of Na+, K+-ATPase of the plasma membrane. The increased membrane permeability for 45Ca and 3H-uridine was recorded 30-40 min after lymphocyte activation with the polyanion, that for 3H-thymidine was seen later (after 4-6 h). It is assumed that the differences between the time of recording high accumulation in the cytoplasm of 45Ca, 3H-uridine and 3H-thymidine and the time of recording high outflow of K+ from lymphocytes are determined by the differences in the sensitivity of the methods applied.