ATRIAL-NATRIURETIC-PEPTIDE GENE-EXPRESSION IN THE RAT GASTROINTESTINAL-TRACT

The presence of ANP prohormone immunoreactivity in rat GI tract sugges ts that it may be an extracardiac site of ANP synthesis. The aim of th is study was to investigate the expression of ANP mRNA in the adult ra t GI tract. ANP mRNA was detected by ribonuclease protection analysis in stomach, small and large intestines, and rectum/anus. The highest c oncentrations of ANP transcripts were found in the proximal stomach, a ntrum, proximal colon, and rectum/anus at levels that ranged from 1 to 10% of that found in cardiac ventricle. Northern blot analysis of tot al RNA from these tissues identified a single 0.9 kb ANP transcript si milar to that detected in heart. Gel filtration chromatography of tiss ue extracts provided evidence for the presence of the complete ANP pro hormone in proximal stomach, antrum, proximal colon and rectum/anus. T hese results demonstrate that the gene for ANP is expressed in specifi c regions of the rat GI tract,suggesting that tissue-specific differen tial regulation of ANP synthesis occurs within the GI tract. (C) 1994 Academic Press, Inc.