Immunohistochemical and immunocytochemical localization of atrial natriuretic polypeptide in human adult and fetal hearts.

Abstract

The localization of atrial natriuretic polypeptide (ANP) in human adult and fetal hearts was investigated by an immunoperoxidase procedure using anti-.alpha.-human ANP antiserum. Light microscopically, the reaction product for ANP was observed in atrial muscle cells and was well confined within both the atrium and atrial septum with the exception of the specialized conducting system of adult heart. No prominent difference in intensity of immunostaining was observed in any part of the atrium. Intracytoplasmic immunoreaction product for ANP was finely granular and generally concentrated at paranuclear sarcoplasm. Electron immunogold stain for ANP of the human adult atrium was also carried out. Ultrastructurally, gold particles were demonstrated in atrial specific granules. Immunoreactive-ANP was also demonstrated in all atria of fetuses at 7, 11, 12, 13, 16 and 17 weeks of gestation. The distribution of the reaction products was similar to those of the adult heart, and there was a tendency of increased staining intensity for ANP with gestational age.