N-acetylcysteine prevents the deleterious effect of tumor necrosis factor-(alpha) on calcium transients and contraction in adult rat cardiomyocytes

• Published in: Circulation (New York, N.Y.) Vol. 109; no. 3; p. 406
• Main Authors: Cailleret, Michel, Amadou, Aïssata, Andrieu-Abadie, Nathalie, Nawrocki, Artur, Adamy, Christophe, Ait-Mamar, Bouziane, Rocaries, François, Best-Belpomme, Martin, Levade, Thierry, Pavoine, Catherine, Pecker, Françoise
• Format: Journal Article
• Language: English
• Published: United States American Heart Association, Inc 27.01.2004
• Subjects: Acetylcysteine - pharmacology; Animals; Calcium - metabolism; Calcium-Binding Proteins - metabolism; Cells, Cultured; Glutathione - analogs & derivatives; Glutathione - metabolism; Glutathione - pharmacology; Male; Myocardial Contraction; Myocytes, Cardiac - drug effects; Myocytes, Cardiac - metabolism; Myocytes, Cardiac - physiology; Rats; Rats, Wistar; Reactive Oxygen Species - metabolism; Sphingomyelin Phosphodiesterase - metabolism; Tumor Necrosis Factor-alpha - antagonists & inhibitors; Tumor Necrosis Factor-alpha - toxicity
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.CIR.0000109499.00587.FF

The negative effect of tumor necrosis factor-alpha (TNF-alpha) on heart contraction, which is mediated by sphingosine, is a major component in heart failure. Because the cellular level of glutathione may limit sphingosine production via the inhibition of the Mg-dependent neutral sphingomyelinase (N-SMase), we hypothesized that cardiac glutathione status might determine the negative contractile response to TNF-alpha. We examined the effects of TNF-alpha in isolated cardiomyocytes obtained from control rats or rats that were given the glutathione precursor N-acetylcysteine (NAC, 100 mg IP per animal). In cardiomyocytes obtained from control rats, 25 ng/mL TNF-alpha increased reactive oxygen species generation and N-SMase activity (500% and 34% over basal, respectively) and decreased the amplitude of [Ca(2+)](i) in response to electrical stimulation (22% below basal). NAC treatment increased cardiac glutathione content by 42%. In cardiomyocytes obtained from NAC-treated rats, 25 ng/mL TNF-alpha had no effect on reactive oxygen species production or N-SMase activity but increased the amplitude of [Ca(2+)](i) transients and contraction in response to electrical stimulation by 40% to 50% over basal after 20 minutes. This was associated with a hastened relaxation (20% reduction in t(1/2) compared with basal) and an increased phosphorylation of both Ser(16)- and Thr(17)-phospholamban residues (260% and 115% of maximal isoproterenol effect, respectively). It is concluded that cardiac glutathione status, by controlling N-SMase activation, determines the severity of the adverse effects of TNF-alpha on heart contraction. Glutathione supplementation may therefore provide therapeutic benefits for vulnerable hearts.