Cyclic AMP-dependent modulation of cardiac Ca channels expressed in Xenopus laevis oocytes.
Cyclic AMP-dependent modulation of cardiac L-type voltage-dependent Ca channel (VDCC) has been probed in Xenopus laevis oocytes injected with poly(A+) RNA from rat heart. A 2 to 3 fold increase of the Ba current amplitude was routinely obtained upon microinjection of cAMP (50-500 microM). Inhibition of protein kinase A (PKA) dramatically reduced the Ba current amplitude, indicating that cAMP-dependent modulation plays an important role in maintaining the basal activity of expressed Ca channels. Moreover, the effects of the DHP agonist Bay K 8644 on kinetic properties of expressed Ba current (IBa,C) were dependent on PKA activation. The results suggest that most expressed cardiac L-type VDCCs are phosphorylated and demonstrate that reconstitution in Xenopus oocytes is a suitable approach to address how phosphorylation regulates VDCC activity.
Lory
P
P
Centre de Recherche de Biochimie Macromoleculaire, UPR 8402 CNRS, U 249 INSERM, Montpellier, France.
Nargeot
J
J
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D000242:Cyclic AMP / Q000494:pharmacology*; D004594:Electrophysiology / Q000379:methods; D005260:Female; D006321:Heart / Q000502:physiology; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D009865:Oocytes / Q000502:physiology*; D011061:Poly A / Q000235:genetics; D047428:Protein Kinase Inhibitors; D012313:RNA / Q000235:genetics; D012333:RNA, Messenger; D051381:Rats; D013997:Time Factors; D014982:Xenopus laevis
D015220:Calcium Channels; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D011061:Poly A; D012313:RNA; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000242:Cyclic AMP; D007545:Isoproterenol