PRESENCE OF ATRIAL-NATRIURETIC-FACTOR PROHORMONE IN ENTEROCHROMAFFIN CELLS OF THE HUMAN LARGE-INTESTINE

Atrial natriuretic factor is a hormone intimately involved in water and salt homeostasis. The heart constitutes the major but not exclusive site of synthesis of this hormone. Among other functions, the gastrointestinal tract has endocrine functions, plays an important role in volume regulation of the body, and seems to be a target organ for atrial natriuretic factor. Therefore, the presence of atrial natriuretic factor was investigated in the human gut. Immunoreactive atrial natriuretic factor was found in intraoperatively obtained samples of normal human colon. Acidic extracts of human large intestine contained about 0.4 pmol/g wet wt of atrial natriuretic factor. Analysis of atrial natriuretic factor immunoreactivity by gel-filtration and reversephase high-performance liquid chromatography showed that about 65% of the immunoreactivity corresponded to the atrial natriuretic factor prohormone and about 35% corresponded to the C-terminal ANF99-126. Immunohistochemistry showed atrial natriuretic factor prohormone location in enterochromaffin cells of the colon mucosa. Altogether, these findings show the presence of atrial natriuretic factor prohormone in enterochromaffin cells of the human large intestine and may suggest this organ as a site of atrial natriuretic factor synthesis in humans. © 1991.