title: Cyclic GMP regulation of the L-type Ca(2+) channel current in human atrial myocytes.
abstract: 1. The regulation of the L-type Ca(2+) current (I(Ca)) by intracellular cGMP was investigated in human atrial myocytes using the whole-cell patch-clamp technique. 2. Intracellular application of 0.5 microM cGMP produced a strong stimulation of basal I(Ca) (+64 +/- 5 %, n = 60), whereas a 10-fold higher cGMP concentration induced a 2-fold smaller increase (+36 +/- 8 %, n = 35). 3. The biphasic response of I(Ca) to cGMP was not mimicked by the cGMP-dependent protein kinase (PKG) activator 8-bromoguanosine 3',5' cyclic monophosphate (8-bromo-cGMP, 0.5 or 5 microM), and was not affected by the PKG inhibitor KT 5823 (100 nM). 4. In contrast, cGMP stimulation of I(Ca) was abolished by intracellular perfusion with PKI (10 microM), a selective inhibitor of the cAMP-dependent protein kinase (PKA). 5. Selective inhibition of the cGMP-inhibited phosphodiesterase (PDE3) by extracellular cilostamide (100 nM) strongly enhanced basal I(Ca) in control conditions (+78 +/- 13 %, n = 7) but had only a marginal effect in the presence of intracellular cGMP (+22 +/- 7 % in addition to 0.5 microM cGMP, n = 11; +20 +/- 22 % in addition to 5 microM cGMP, n = 7). 6. Application of erythro-9-[2-hydroxy-3-nonyl]adenine (EHNA, 30 microM), a selective inhibitor of the cGMP-stimulated phosphodiesterase (PDE2), fully reversed the secondary inhibitory effect of 5 microM cGMP on I(Ca) (+99 +/- 16 % stimulation, n = 7). 7. Altogether, these data indicate that intracellular cGMP regulates basal I(Ca) in human atrial myocytes in a similar manner to NO donors. The effect of cGMP involves modulation of the cAMP level and PKA activity via opposite actions of the nucleotide on PDE2 and PDE3.
authors.affiliation: Laboratoire de Cardiologie Cellulaire et Moléculaire, INSERM U-446, Université de Paris-Sud, Faculté de Pharmacie, F-92296 Châtenay-Malabry, France.
authors.forename: G
authors.initials: G
authors.lastname: Vandecasteele
authors.forename: I
authors.initials: I
authors.lastname: Verde
authors.forename: C
authors.initials: C
authors.lastname: Rücker-Martin
authors.forename: P
authors.initials: P
authors.lastname: Donzeau-Gouge
authors.forename: R
authors.initials: R
authors.lastname: Fischmeister
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D002648:Child; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D006325:Heart Atria / Q000166:cytology; D006801:Humans; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000201:enzymology*; D009206:Myocardium / Q000166:cytology*; D018408:Patch-Clamp Techniques; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D015363:Quinolones / Q000494:pharmacology; D013268:Stimulation, Chemical
chemical_list: D020746:Calcium Channels, L-Type; D010726:Phosphodiesterase Inhibitors; D015363:Quinolones; C016276:8-bromocyclic GMP; C021294:cilostamide; D017868:Cyclic AMP-Dependent Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D010727:Phosphoric Diester Hydrolases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; C517275:PDE2A protein, human; D006152:Cyclic GMP