Pimobendan inhibits the production of proinflammatory cytokines and gene expression of inducible nitric oxide synthase in a murine model of viral myocarditis
Atsushi Iwasaki, MDa,
Akira Matsumori, MD, PhD, FACCa,
Takehiko Yamada, MD, PhDa,
Tetsuo Shioi, MD, PhDa,
Weizhong Wang, MD, PhDa,
Koh Ono, MD, PhDa,
Ryosuke Nishio, MDa,
Masaharu Okada, MDa and
Shigetake Sasayama, MD, PhD, FACCa
a Department of Cardiovascular Medicine, Kyoto University, Kyoto, Japan
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Figure 1 Effect of pimobendan on survival rate after EMC virus inoculation. Beyond seven days, the survival rate was improved in a dose-dependent manner. Treatment with pimobendan, 1 mg/kg/day, significantly reduced mortality on day 14. * = p < 0.02 versus control. Each group consists of thirty mice.
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Figure 2 Typical histopathologic changes found seven days after EMC virus inoculation. A and B: Heart from a control mouse. C and D: Heart from a mouse treated with pimobendan 1 mg/kg. Extensive myocardial necrosis and cellular infiltration are found in the control preparation. In the mouse treated with pimobendan, less myocardial cellular infiltration exists despite an equivalent amount of myocardial necrosis. Hematoxylin and eosin stain—original magnification: A and C, x 40, reduced by 65%; B and D, x 200, reduced by 65%.
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Figure 4 Effect of pimobendan on intracardiac NO production. The concentrations of nitrite/nitrate, stable endproducts of NO, in the pimobendan 1 mg/kg group (n = 5) were 43% lower than in the control group (n = 5). * = p < 0.01 versus control.
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Figure 5 Quantification of iNOS mRNA in the hearts using RT-PCR. A: Total RNA was extracted from the hearts in the pimobendan 1 mg/kg group and the control group. Each PCR product was separated by electrophoresis on a 5% polyacrylamide gel. The gels were dried and autoradiographed. nh-DNA = nonhomologous DNA. B: The log of the ratio of iNOS or G3PDH target radioactivity to the nh-DNA fragment radioactivity was plotted against the log of the number of the nh-DNA fragment molecules added to each PCR reaction. The number of iNOS or G3PDH cDNA molecules was obtained from the point where log (iNOS or G3PDH/the nh-DNA fragment) was equal to zero. C: The number of iNOS or G3PDH cDNA was expressed as attomoles/µg of total RNA. The iNOS gene expression in the pimobendan 1 mg/kg group was 74% lower than that of the control group. * = p < 0.01 versus control.
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, IL-1ß, and IL-6 measured on day seven after EMC virus inoculation. The intracardiac TNF-