IN-VITRO EFFECTS OF ENDOTHELIN-1 ON SOMATOSTATIN AND THYROTROPIN-RELEASING-HORMONE RELEASE FROM THE RAT STOMACH

The effects of endothelin (ET) 1 on the release of somatostatin (SS) a nd thyrotropin-releasing hormone (TRH) from the rat stomach were studi ed in vitro. The rat stomach was incubated in medium 199 with 1.0 mg/m l of bacitracin (pH 7.4) for 20 min. The amounts of SS and TRH release d into the medium were measured by individual radioimmunoassays. With the addition of ET-1, the release of SS from the rat stomach was inhib ited significantly in a dose-relatedmanner, hereas TRH leased from the stomach was enhanced significantly. These effects of ET-1 on SS or TR H release were blocked by BQ-485, a blocker of ETA receptor. These fin dings suggest that ET-1 inhibits SS and stimulates TRH release from th e rat stomach in vitro, and that these effects are mediate via ETA rec eptor.