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Figure 5 Immunohistochemical localization of endothelial-type NOS III in human heart. (A) Staining of blood vessels within the myocardium. The anti-NOS III antibody selectively stained vascular endothelium (dCMP = idiopathic dilated cardiomyopathy; iCMP = ischemic cardiomyopathy; mCMP = postmyocarditis cardiomyopathy and NF = nonfailing heart). (B) Staining of cardiomyocytes (NF, dCMP, iCMP and mCMP) on the same slices as the blood vessels in A. Incubations with a rabbit nonimmune serum gave no staining in the myocardium (Neg, negative control, slice object: mCMP). The average diameter of cardiomyocytes from failing hearts was increased compared to NF hearts. Magnification in A and B 400x. Photomicrographs are representative of at least four experiments with identical results.