title: Role of prostaglandin-mediated cyclic AMP formation in protein kinase C-dependent secretion of atrial natriuretic peptide in rat cardiomyocytes.
abstract: The role of endogenous prostaglandin production in phorbol diester-induced myocardial atrial natriuretic peptide (ANP) secretion was investigated in cultured spontaneously beating ventricular rat cardiomyocytes. Incubation of cells with 4 beta-phorbol 12-myristate 13-acetate (PMA; 0.1 microM) led to a rapid response in ANP release, a response accompanied by increases in cellular prostacyclin (PGI2) production, cyclic AMP (cAMP) formation and spontaneous contraction frequency. Although PMA-induced ANP secretion exhibited the pharmacological profile of a protein kinase C (PKC)-mediated event, the response was abolished in the presence of the cyclo-oxygenase inhibitors indomethacin (10 microM) and diclofenac (1 microM), indicating that endogenous prostaglandin production is responsible for PMA-induced ANP secretion in this system. Confirming this, PMA-induced ANP secretion was strongly correlated with endogenous formation of 6-oxo-prostaglandin F1 alpha (r = 0.93, P < 0.0005, n = 11), and exogenously applied PGI2, prostaglandin E2 (PGE2) or prostaglandin F2 alpha (PGF2 alpha) elicited simultaneous increases in cAMP formation, contraction frequency and ANP secretion in these cells. Furthermore, PMA-induced cAMP formation was abolished in the presence of either diclofenac or indomethacin, whereas the cAMP-elevating agent forskolin (0.1 microM) mimicked the secretory and chronotropic effect of PMA in these cells. A role for cAMP in PMA-induced ANP secretion was also apparent insofar as PMA-induced ANP release was substantially decreased in the presence of the Rp-diastereomer of 3',5'-cyclic adenosine monophosphorothioate (Rp-cAMPS; 10 microM), whereas the cAMP-mimetic agent dibutyryl cAMP (10 microM) provoked a rapid increase in ANP secretion in this system. Finally, the Ca(2+)-channel antagonist nifedipine (0.1 microM) severely decreased PGI2-, PGE2- and PMA-induced ANP secretion without affecting PGF2 alpha-induced peptide release, suggesting that PGI2 and/or PGE2, but not PGF2 alpha, are the prostanoids involved in PMA-induced ANP release. Taken together, these results suggest that PKC activation induces ANP secretion in spontaneously beating rat ventricular cardiomyocytes via an autocrine pathway involving increased PGI2 and/or PGE2 formation, a response leading to the activation of a myocardial adenylate cyclase and, subsequently, to that of a nifedipine-sensitive Ca2+ channel.
authors.affiliation: Department of Medicine, Geneva University Hospital, Switzerland.
authors.forename: D J
authors.initials: DJ
authors.lastname: Church
authors.forename: V
authors.initials: V
authors.lastname: Van der Bent
authors.forename: M B
authors.initials: MB
authors.lastname: Vallotton
authors.forename: U
authors.initials: U
authors.lastname: Lang
mesh_terms: D015121:6-Ketoprostaglandin F1 alpha / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D009320:Atrial Natriuretic Factor / Q000096:biosynthesis* / Q000378:metabolism; D003994:Bucladesine / Q000494:pharmacology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D004008:Diclofenac / Q000494:pharmacology; D015237:Dinoprost / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D011464:Epoprostenol / Q000378:metabolism / Q000494:pharmacology; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006352:Heart Ventricles; D007213:Indomethacin / Q000494:pharmacology; D007700:Kinetics; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D011453:Prostaglandins / Q000494:pharmacology* / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D011453:Prostaglandins; D013873:Thionucleotides; D004008:Diclofenac; C016957:adenosine-3',5'-cyclic phosphorothioate; D015121:6-Ketoprostaglandin F1 alpha; D003994:Bucladesine; D009320:Atrial Natriuretic Factor; D015237:Dinoprost; D011464:Epoprostenol; D000242:Cyclic AMP; D011493:Protein Kinase C; D009543:Nifedipine; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate; D007213:Indomethacin