Atrial natriuretic peptide (ANP) in rat gastrointestinal tract.

Acid extracts of rat stomach and small intestine contained 8.6 +/- 3.7 and 39 +/- 15 ng/g of immunoreactive atrial natriuretic peptide (ANP). When studied by gel filtration and reverse-phase high-performance liquid chromatography, the stomach immunoreactivity consisted of multiple components, whereas the small intestine contained mostly proANP and ANP 1-28-like material. These findings indicate that ANP may have a role in the physiology of the gastrointestinal tract, e.g. in the regulation of water and electrolyte absorption.