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In contrast to excitable tissues where calcium channels are well characterized, the nature of the B lymphocyte calcium channel is unresolved. Here, we demonstrate by single cell analysis of freshly isolated rat B cells that the anti-immunoglobulin (Ig)-induced calcium influx takes place through a channel which shares pharmacologic and serologic properties with the L-type calcium channel found in excitable tissues. It is sensitive to the dihydropyridines nicardipine and Bay K 8644, to calciseptine, and to an anti-peptide antibody raised against the alpha1 subunit of the L-type calcium channel, but is voltage-insensitive. Anti-alpha1 and anti-alpha2 antibodies stain B but not T lymphocytes. Application of a cGMP agonist, measurement of cGMP levels in anti-Ig-stimulated B cells, and examining the effect of a guanylyl cyclase inhibitor on the anti-Ig response show that cGMP mediates the influx. This possibly involves a cGMP-dependent protein kinase. The anti-Ig-induced response is not abolished by prior treatment of B cells with a high dose of thapsigargin. These findings undermine the widely held belief of a categorical divide between excitable and non-excitable tissue calcium channels, demonstrate the limitations of the capacitative calcium influx theory, and point to a distinction between the calcium response mechanisms utilized by B and T lymphocytes.

Original publication

DOI

10.1074/jbc.271.13.7297

Type

Journal article

Journal

J Biol Chem

Publication Date

29/03/1996

Volume

271

Pages

7297 - 7300

Keywords

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester, 8-Bromo Cyclic Adenosine Monophosphate, Animals, Antibodies, B-Lymphocytes, Calcium, Calcium Channel Blockers, Calcium Channels, Calcium Channels, L-Type, Cell Membrane, Cell Separation, Cells, Cultured, Cyclic GMP, Cyclic GMP-Dependent Protein Kinases, Egtazic Acid, Elapid Venoms, Immunoglobulin D, Immunoglobulin M, Kinetics, Lymph Nodes, Nicardipine, Rats