title: Calcium channels are present in the apical plasma membranes of the hepatopancreatic B-cells of Marsupenaeus japonicus.
abstract: This study demonstrates the existence of calcium channels in the apical membranes of the hepatopancreatic blister (B) cells of Marsupenaeus japonicus. Using brush-border membrane vesicles we demonstrated that the channel-mediated calcium passive flux was saturable and was stimulated by a transmembrane electrical potential difference and inhibited by barium. We raised a monoclonal antibody (Mab 24A4) against the calcium channel, which allowed us to inhibit the channel-mediated calcium uptake. By immunocytochemistry, using Mab 24A4, we demonstrated that these channels are located at the apical membrane of hepatopancreatic B cells. Finally, by measuring the calcium uptake in R- and B-enriched cell suspensions, we showed that only the plasma membrane of the B cells expresses a channel-mediated calcium uptake inhibited by barium, verapamil and the monoclonal antibody 24A4. The plasma membrane of R cells did not show calcium channels.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism / Q000494:pharmacology*; D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects* / Q000276:immunology; D002132:Calcium Radioisotopes; D002462:Cell Membrane / Q000187:drug effects*; D003445:Crustacea / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D043143:Hepatopancreas / Q000166:cytology*; D007150:Immunohistochemistry; D008564:Membrane Potentials / Q000187:drug effects; D008871:Microvilli / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002132:Calcium Radioisotopes; D001464:Barium; D014700:Verapamil; D002118:Calcium