Role of membrane potential in the regulation of lectin-induced calcium uptake.
Incubation of lymphocytes with mitogenic lectins triggers Ca2+ uptake. This increase in free cytoplasmic Ca2+ is postulated to be an important signal in the initiation of DNA synthesis. Transmembrane fluxes of monovalent ions and changes in membrane potential are also associated with lectin-induced activation of lymphocytes. We have examined the relationship between extra-cellular monovalent ion substitution, the associated electrical potential changes (measured with cyanine dyes), phytohemagglutinin-induced Ca2+ uptake (measured with Quin-2) and proliferation in human T cells. The results show that (1) the magnitude of the increase in free cytoplasmic Ca2+ concentration is correlated with the extent of the lymphoproliferative response, (2) lectin-induced Ca2+ fluxes are sensitive to membrane potential, decreasing with depolarization, and are likely conductive, and (3) the presence of extra-cellular Na+ during incubation with phytohemagglutinin is not essential to mitogenic triggering.
D002118:Calcium / Q000378:metabolism*; D002412:Cations / Q000494:pharmacology; D002414:Cations, Monovalent / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D003593:Cytoplasm / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D006801:Humans; D037102:Lectins / Q000494:pharmacology*; D008214:Lymphocytes / Q000166:cytology / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D010835:Phytohemagglutinins / Q000494:pharmacology
D002412:Cations; D002414:Cations, Monovalent; D037102:Lectins; D010835:Phytohemagglutinins; D004247:DNA; D002118:Calcium