DISTRIBUTION AND EXPRESSION OF ADRENOMEDULLIN IN HUMAN GASTROINTESTINAL TISSUE

Adrenomedullin (AM) is a biologically active peptide recently isolated from phaeochromocytoma. We report here the distribution and character ization of immunoreactive AM and gene expression of AM in human gastro intestinal tissue. Using a sensitive radioimmunoassay system for the p eptide, immunoreactive human AM was detected in the stomach, duodenum, jejunum, ileum and colon. The AM concentration of these tissues was a bout 0.4-0.8 pmol/g wet tissue. Reverse phase and gel filtration high- performance liquid chromatographies showed that most of the immunoreac tive AM in stomach and jejunum was identical to authentic human AM. By northern blot analysis, human AM mRNA was found to be expressed ubiqu itously in the human gastrointestinal tissues. Furthermore, an immunoh istochemical study revealed that immunoreactive AM cells were present in the gastrointestinal glands. These results suggest that AM may E-la y some role as a gastrointestinal hormone.