Cross-linking of surface immunoglobulin on B lymphocytes induces both intracellular Ca2+ release and Ca2+ influx: analysis with indo-1.
The new Ca2+-probe indo-1 has a high fluorescence intensity, which allows low intracellular dye loadings. Stimulation of indo-1-loaded mouse B cells with anti-Ig antibodies provoked rapid rise of free cytoplasmic Ca2+ from 100 nM to greater than 1 microM, followed by a decline to a plateau at 300-400 nM. The initial rapid rise was not detected in quin2-loaded cells, presumably due to the Ca2+-buffering effects of the dye. The sustained Ca2+ increase was due to influx, whereas the initial rise was caused by release from intracellular stores. The magnitudes of Ca2+ release and inositol trisphosphate release were closely correlated. Concanavalin A does not provoke inositol trisphosphate release in mouse B cells. It did not induce a rapid initial Ca2+ rise in indo-1-loaded B cells either, but only a sustained increase to 200-300 nM. Finally, Ca2+ influx induced by both anti-Ig and concanavalin A were not affected by membrane depolarization.
D000634:Aminoquinolines; D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D003208:Concanavalin A / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D007211:Indoles; D007295:Inositol Phosphates / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D011188:Potassium / Q000494:pharmacology; D011947:Receptors, Antigen, B-Cell / Q000502:physiology*
D000634:Aminoquinolines; D007211:Indoles; D007295:Inositol Phosphates; D011947:Receptors, Antigen, B-Cell; D003208:Concanavalin A; C035738:Quin2-acetoxymethyl ester; C048960:indo-1; D011188:Potassium; D002118:Calcium