Two types of Ca channel in rat pancreatic beta-cells.
Ba currents flowing through single Ca-channels were recorded from cell-attached patches on rat pancreatic beta-cells. Two types of voltage-activated Ca-channels were found. The first (T-type) had a single channel conductance of 8 pS in 100 mM Ba, was activated at a low threshold (around -50mV) and inactivated by holding potentials positive to -40 mV. These properties are similar to those described for T-type channels in other preparations. The second type of Ca-channel (L-type) had a single channel conductance of 20pS in 100 mM Ba, was activated at a higher threshold (greater than -30mV), showed little inactivation during a 250 ms pulse and could be activated from a holding potential of -40mV. The dihydropyridine agonist BAY K 8644 selectively prolonged L-type Ca-channel openings. These properties are characteristic of L-type Ca-channels.
University Laboratory of Physiology, Oxford, UK.
F M
FM
Ashcroft
R P
RP
Kelly
P A
PA
Smith
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000502:physiology; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D046508:Culture Techniques; D007515:Islets of Langerhans / Q000187:drug effects / Q000502:physiology*; D051381:Rats
D015220:Calcium Channels; D001464:Barium; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester