Affiliation:
1. From the VA Medical Center and the Cardiovascular Research Institute and Department of Medicine, University of California, San Francisco, Calif. Present address of D.G.R. is Department of Medicine, University of Louisville, Louisville, Ky.
Abstract
Abstract
—Cultured neonatal rat cardiac myocytes have been used extensively to study cellular and molecular mechanisms of cardiac hypertrophy. However, there are only a few studies in cultured mouse myocytes despite the increasing use of genetically engineered mouse models of cardiac hypertrophy. Therefore, we characterized hypertrophic responses in low-density, serum-free cultures of neonatal mouse cardiac myocytes and compared them with rat myocytes. In mouse myocyte cultures, triiodothyronine (T3), norepinephrine (NE) through a β-adrenergic receptor, and leukemia inhibitory factor induced hypertrophy by a 20% to 30% increase in [
3
H]phenylalanine-labeled protein content. T3 and NE also increased α-myosin heavy chain (MyHC) mRNA and reduced β-MyHC. In contrast, hypertrophic stimuli in rat myocytes, including α
1
-adrenergic agonists, endothelin-1, prostaglandin F
2α
, interleukin 1β, and phorbol 12-myristate 13-acetate (PMA), had no effect on mouse myocyte protein content. In further contrast with the rat, none of these agents increased atrial natriuretic factor or β-MyHC mRNAs. Acute PMA signaling was intact by extracellular signal–regulated kinase (ERK1/2) and immediate-early gene (fos/jun) activation. Remarkably, mouse but not rat myocytes had hypertrophy in the absence of added growth factors, with increases in cell area, protein content, and the mRNAs for atrial natriuretic factor and β-MyHC. We conclude that mouse myocytes have a unique autonomous hypertrophy. On this background, T3, NE, and leukemia inhibitory factor activate hypertrophy with different mRNA phenotypes, but certain Gq- and protein kinase C–coupled agonists do not.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Cardiology and Cardiovascular Medicine,Physiology
Cited by
94 articles.
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