1. Detection of ligand-activated conductive Ca2+ channels in human B lymphocytes.
- Author
-
MacDougall SL, Grinstein S, and Gelfand EW
- Subjects
- Chelating Agents, Egtazic Acid analogs & derivatives, Humans, Indicators and Reagents, Ligands, Membrane Potentials, Potassium metabolism, B-Lymphocytes metabolism, Calcium metabolism, Ion Channels analysis
- Abstract
It has been assumed that uptake of extracellular Ca2+ occurs through ligand-activated Ca2+ channels in anti-IgM stimulated human B cells. If so, then uptake should be associated with a depolarizing inward current. Instead, a hyperpolarization due to Ca2+-sensitive K+ conductance is observed. To demonstrate conductive Ca2+ channels in human B lymphocytes, we loaded the cells with 1,2-bis-(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetate (BAPTA), an intracellular Ca2+ chelating agent. This increased the magnitude of the Ca2+ current and delayed the Ca2+-dependent K+ conductance. In BAPTA-loaded B cells suspended in Ca2+-free medium and activated with anti-IgM, reintroduction of Ca2+ resulted in a depolarization that was inhibited by high (microM) concentrations of verapamil and was observed when Ca2+ was replaced by Ba2+ but not Mg2+. These data demonstrate the opening of selective, Ca2+ conductive channels in human B cells following cross-linking of surface immunoglobulins.
- Published
- 1988
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