Single Ca channel currents in mouse pancreatic B-cells.
Barium currents flowing through single Ca2+ channels were recorded from outside-out patches isolated from mouse pancreatic B-cells. Only one type of Ca2+ channels was observed. In 110 mM Ba2+, the single channel conductance was 24pS (at negative membrane potentials) and the current amplitude at 0 mV was -0.7 pA. Channel openings were activated by depolarisations more positive than -30 mV and showed little inactivation during 200 ms pulses. Open times were increased by BAY K 8644 an decreased by micromolar Cd2+. Channel activity was subject to rundown in excised patches and little activity remained after 10 min. These properties resemble those of L-type Ca2+ channels in other tissues. It is suggested that this Ca2+ channel participates in the generation of the B-cell action potential and mediates the increase in Ca2+ influx required for insulin secretion.
Rorsman
P
P
Department of Medical Physics, Göteborg, Sweden.
Ashcroft
F M
FM
Trube
G
G
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000200:Action Potentials; D000818:Animals; D001464:Barium / Q000378:metabolism; D002104:Cadmium / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004553:Electric Conductivity; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D051379:Mice
D015220:Calcium Channels; D002104:Cadmium; D001464:Barium; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester