Author + information
- Received September 8, 1995
- Revision received August 5, 1996
- Accepted August 9, 1996
- Published online November 15, 1996.
- Yuji Hiraoka, MD, PhD∗,
- Chiharu Kishimoto, MD, PhD,
- Hitoshi Takada, MD,
- Michiyo Nakamura, BA,
- Masahiko Kurokawa, PhD,
- Hiroshi Ochiai, MD, PhD and
- Kimiyasu Shiraki, MD, PhD
- ↵∗Address for correspondence:: Dr. Chiharu Kishimoto, The Second Department of Internal Medicine, Faculty of Medicine, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-01, Japan.
Objectives. This study sought to investigate the effects of nitric oxide inhibition in a murine model of coxsackievirus B3 myocarditis.
Background. Little is known about the contribution of nitric oxide to the pathophysiology of myocarditis.
Methods. Antiviral activity was tested in vitro using nitric oxide inhibition by treatment with activated macrophages of NG-nitro-l-arginine methyl ester and NG-nitro-d-arginine methyl ester (both at 100 μg/ml) were administered to C3H/He mice early (days 0 to 14) and late (days 14 to 35) after infection with coxsackievirus B3.
Results. In the in vitro experiments with interferon-gamma-and lipopolysaccharide-induced activated murine macrophages, treatment with the nitric oxide synthase inhibitor NG-nitro-l-arginine methyl ester, but not its inactive enantiomer NG-nitro-d-arginine methyl ester, restored coxsackievirus B3 titers. In the in vivo experiments in the early treatment group, myocardial virus titers were higher in NG-nitro-l-arginine methyl ester-treated than infected untreated animals, and both inflammatory cell infiltration and necrosis were more severe. In the late treatment group, more severe necrosis and more dense myocardial and perivascular fibrosis were observed in NG-nitro-l-arginine methyl ester-treated than in infected untreated animals. NG-Nitro-d-arginine methyl ester administration was ineffective.
Conclusions. Nitric oxide inhibition increases myocardial virus titers, resulting in the aggravation of cardiac pathology in the early stage of coxsackievirus B3 myocarditis. In the late stage, it induces more severe cardiomyopathic lesions. Nitric oxide plays a defensive role in the pathogenesis of coxsackievirus B3 myocarditis.
☆ This work was supported in part by research grants from the Japanese Heart Foundation, Conference on Coronary Artery Disease, Tokyo; an Education Fellowship from Toyama Medical and Pharmaceutical University; an Iwaki Fellowship, Tokyo; a Toyama First Bank Fellowship; Grants 01570478, 03670445 and 06670702 from the Japanese Education of Science and Welfare, Tokyo; the Uehara Memorial Foundation, Tokyo; and the Kanae Shinyaku Foundation, Osaka. This study was presented in part at the 68th Scientific Sessions of the American Heart Association, Anaheim, California, November 1995.
- Received September 8, 1995.
- Revision received August 5, 1996.
- Accepted August 9, 1996.