Atrial natriuretic peptide in the ventricles of patients with dilated cardiomyopathy and human foetuses.

Immunohistochemical examination of atrial natriuretic peptide (ANP) was performed on endomyocardial biopsy specimens from 8 patients with dilated cardiomyopathy (DCM), 10 human foetal hearts obtained from legal abortions, and 8 adult hearts from autopsy control subjects without cardiovascular diseases. The indirect immunoperoxidase method, using specific monoclonal antibody to alpha-human ANP was employed. Immunoreactivity was observed at the light microscope level in the working ventricular cardiocytes of all patients with DCM as dark-brown, granular deposits. Peripheral plasma levels of ANP in these patients were also increased. In control adult hearts without cardiovascular diseases, immunoreactivity was detected both in the atria and in the ventricular impulse-conducting system, although the working ventricular cardiocytes were not immunoreactive. In foetal hearts, immunoreactivity was detected not only in the atria and ventricular impulse-conducting system, but also in the working ventricular cardiocytes. We conclude that ANP is present in the ventricular impulse-conducting system of the human hearts, and that ANP is also present in the working ventricular cardiocytes in patients with DCM as well as in human foetuses.