Membrane potential changes during mitogenic stimulation of mouse spleen lymphocytes

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Abstract
By monitoring differences in accumulation of the lipophilic cation [3H]tetraphenylphosphonium in media containing low or high K concentrations, the membrane potential of lymphocytes from various sources has been estimated. On the basis of this method, the potential of normal mouse spleen lymphocytes (T [thymus-derived] and B [bone marrow-derived] cells) is -65 .+-. 2 mV (mean .+-. SEM [standard error of the mean], interior negative). During the course of mitogenic stimulation of concanavalin [Con] A, [Escherichia coli] lipopolysaccharide or fetal calf serum, the membrane potential of murine spleen lymphocytes changes systematically according to the following pattern: early depolarization lasting 2-3 h, repolarization over the next 7 h, a final hyperpolarization phase during the last 24-48 h. During repolarization and hyperpolarization there is a direct correlation between membrane potential and DNA synthesis, as judged by [3H]thymidine incorporation. By using isolated T and B cells, it is observed that Con A depolarizes T cells only; lipopolysaccharide depolarizes B cells only. Both mitogens exhibit the same specificity for depolarization as for mitogenic stimulation. The transition of lymphocytes from a resting state to mitotic activity is probably initiated by depolarization of the plasma membrane.