The regulation of L-type Ca2+ currents in rat cardiac myocytes.
The regulation of L-type Ca2+ current in isolated rat cardiac cells was studied using the perforated patch-clamp technique. A dual effect of the cAMP-dependent phosphorylation activator, isoproterenol, at different holding potentials (V(h)) was shown. The currents increased at V(h) = -50 mV and decreased at V(h) = -30 mV. A dihydropyridine agonist, BAY K 8644, and isoproterenol had an additive effect on the activation of Ca2+ channels at holding potentials close to the resting potential. The additivity was disturbed at more positive V(h). The activating effect of BAY K 8644 did not virtually change in the presence of a protein kinase blocker, H8, and a phosphatase activator, acetylcholine. The results were interpreted within the framework of a two-site phosphorylation model with two independent pathways of Ca2+ current regulation.
Markevich
N I
NI
Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region.
Korystova
A F
AF
Grichenko
A S
AS
Lankina
D A
DA
Kokoz
Y M
YM
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000109:Acetylcholine / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002120:Calcium Channel Agonists / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000502:physiology*; D002478:Cells, Cultured; D004553:Electric Conductivity; D004594:Electrophysiology; D007545:Isoproterenol / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D007700:Kinetics; D009206:Myocardium / Q000166:cytology; D010766:Phosphorylation; D051381:Rats
D000318:Adrenergic beta-Agonists; D002120:Calcium Channel Agonists; D020746:Calcium Channels, L-Type; D007546:Isoquinolines; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; C053177:N-(2-(methylamino)ethyl)-5-isoquinolinesulfonamide; D007545:Isoproterenol; D000109:Acetylcholine