Atrial natriuretic factor. Immunohistochemical localization in the specific atrial granules of the rat heart.

Atrial natriuretic peptides (atrial natriuretic factor, ANF) were localized in rat heart atria using immunohistochemical methods. A large number of heavily stained granules were detected mainly in the vicinity of the nuclei of the atrial muscle cells, but some staining was also present in granules located near the sarcolemma. The results show that the specific atrial granules are loaded with atrial natriuretic peptides.