Light and Electron Microscopic localization of inducible nitric oxide synthase in the heart of rats with myocarditis

Nitric oxide synthase (NOS) is an enzyme involved in the synthesis of nitric oxide (NO). The inducible form of NOS (iNOS) is induced in the presence of cytokines and produces massive amounts of NO which may be harmful to living tissue. In acute myocarditis, a serious disease which can be fatal, extensive myocardial cell damage associated with massive inflammatory cell infiltration is usually observed and large amounts of cytokines are released from inflammatory cells. However, the mechanism of the heart tissue injury is still unclear. In this study, we investigated the role of iNOS in the myocardial tissue injury in acute myocarditis.The heart tissue specimens were taken from Lewis rats with experimentally induced autoimmune myocarditis. An immunohistochemical study was performed using iNOS antibody raised in New Zealand white rabbits immunized with synthetic peptides (17 amino acids) corresponding to the C-terminal of macrophage iNOS. The specificity of the antibody was confirmed by Western blot analysis. Immunoelectron microscopic studies were carried out by the gold-labeled IgG method using ultrathin sections of LR white resin-embedded material.