Membrane potential changes during IgE-mediated histamine release from rat basophilic leukemia cells

The membrane potential of rat basophilic leukemia cells (RBL-2H3 cell line) has been determined by monitoring the distribution of the lipophilic [³H] tetraphenylphosphonium cation between the cells and the extracellular medium. By this method, the determined potential of these cells, passively sensitized with IgE, is -93±5 mV (mean±sem, interior negative). Almost 40% of this membrane potential is rapidly collapsed upon the addition of the proton carrier, carbonyl cyanide p-trifluoromethoxyphenyl hydrazone (FCCP). It is suggested that the FCCP-sensitive fraction of the total membrane potential results from the accumulation of this cation by the mitochondria, which mantains a negative membrane potential. Thus, the resting plasma membrane potential of these cells equals -55±6 mV. During the process of immunological stimulation by antibodies directed against cell membrane bound IgE, the membrane potential decreases. Moreover, there is a correlation between the extent of degranulation of the cells and the depolarization. It is concluded that in common with other secretory systems, depolarization of the plasma membrane is involved in the stimulus-secretion coupling of the histamine secreting RBL cells.