title: Nitric oxide-mediated inhibition of DNA synthesis was attenuated in hypertrophied neonatal rat ventricular myocytes.
abstract: The antiproliferative action of nitric oxide (NO) has been well established and increased production was reported in the infarcted rat heart. Concomitantly, increased DNA synthesis and hyperplasia of cardiac myocytes were documented in the hypertrophied myocardium. Despite these observations, the effect of NO on DNA synthesis in hypertrophied cardiac myocytes remains unexamined. Hypertrophy of the non-infarcted left ventricle (NILV) in 1-week post-MI rats was characterized by the increased prepro-ANP and reduction of alpha-myosin heavy chain protein expression. Inducible NO synthase was expressed in the NILV and associated with a concomitant attenuation of MnSuperoxide dismutase protein content. The latter data suggest that an antiproliferative action of NO in the hypertrophied NILV may proceed via either a cyclic GMP-dependent pathway and/or facilitated by a peroxynitrite-dependent mechanism. In neonatal rat ventricular myocytes (NNVM), the NO donor S-nitroso-N-acetyl-penicillamine (SNAP) promoted a dose-dependent attenuation of DNA synthesis via a cyclic GMP-independent pathway. The permeable superoxide dismutase mimetic and peroxynitrite scavenger MnTBAP abrogated SNAP-dependent attenuation of DNA synthesis in NNVM. MnTBAP failed to inhibit SNAP-mediated recruitment of extracellular signal regulated kinase 1/2 (ERK1/2) but partially attenuated p38 phosphorylation. In hypertrophied NNVM induced by norepinephrine, SNAP-mediated peroxynitrite-dependent inhibition of DNA synthesis, ERK1/2 and p38 phosphorylation were significantly attenuated. Collectively, these data suggest that despite a favourable environment for NO and subsequent peroxynitrite generation in the NILV, hypertrophied cardiac myocytes may be partially refractory to their biological actions.
authors.affiliation: Department of Physiology, University of Montreal, Montreal, Que., Canada.
authors.forename: Viviane
authors.initials: V
authors.lastname: El-Helou
authors.forename: Samar
authors.initials: S
authors.lastname: Bel-Hadj
authors.forename: Jessica
authors.initials: J
authors.lastname: Drapeau
authors.forename: Robert
authors.initials: R
authors.lastname: Clement
authors.forename: Hugues
authors.initials: H
authors.lastname: Gosselin
authors.forename: Angelino
authors.initials: A
authors.lastname: Calderone
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D006152:Cyclic GMP / Q000378:metabolism; D004247:DNA / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D006352:Heart Ventricles / Q000473:pathology; D006984:Hypertrophy; D017379:Hypertrophy, Left Ventricular / Q000473:pathology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D032342:Muscle Cells / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D030421:Peroxynitrous Acid / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000378:metabolism; D024723:Ventricular Myosins / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D020030:Nitric Oxide Donors; C110881:S-nitro-N-acetylpenicillamine; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D004247:DNA; D019001:Nitric Oxide Synthase; D013482:Superoxide Dismutase; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D024723:Ventricular Myosins; D010396:Penicillamine; D006152:Cyclic GMP