Differential nitric oxide synthase activity in ischemic and idiopathic dilated cardiomyopathy

Dilated cardiomyopathy is a heart muscle disease with unknown cause or asso ciation characterized by ventricular dilatation and impaired systolic funct ion.(1) Several immunologic phenomena have been implicated as triggers incl uding viruses,(2) autoimmunity, and endotoxin.(3) What is clear is that "in flammation," either acute or chronic, appears to be the common denominator leading to a state of persistent myocardial dysfunction. Previous work from this institution has for the first time shown the association between a pr oinflammatory cytokine and nitric oxide in dilated cardiomyopathy by demons trating the immunohistochemical tissue expression of tumor necrosis factor alpha and inducible nitric oxide synthase in human cardiac tissue.(4) To in vestigate cytokine-induced nitric oxide synthase activity as a possible pat hogenetic mechanism, we measured plasma nitrite and interleukin 1 beta (IL1 beta) levels in patients with idiopathic dilated cardiomyopathy (IDC), isc hemic cardiomyopathy (IC), and in normal controls by measuring levels of cy tokine antigen and nitrite in the circulation.