Atrial natriuretic peptide deposited as atrial amyloid fibrils.

Deposition of amyloid in the atria is exceedingly common in the aging heart. We have extracted amyloid fibrils from atria and purified a major protein which had N-terminal amino acid sequence identical to that of atrial natriuretic peptide (ANP). Antisera to ANP and to the amyloid fibril protein both labelled atrial muscle cells and atrial amyloid in an identical way.