Presence of immunoreactive endothelin in human saliva and rat parotid gland

Abstract The presence of immunoreactive endothelin (IR-ET) in human saliva and rat parotid gland was investigated by radioimmunoassay. The IR-ET concentration (mean±SEM) in saliva taken from normal volunteers was 2.0±0.2 pmol/l ( n =15 ). The IR-ET concentration in rat parotid gland was 19.2±2.2 fmol/g wet weight ( n =10 ). Fast protein liquid chromatography (FPLC) of human saliva extract revealed 6 peaks; one peak eluting in the void volume, one in a position between ET-1 and -3, and the other four in the positions of synthetic ET-1, -2, -3 and big ET(1–38), respectively. A similar pattern of rat parotid gland extract was noted with FPLC, except that there was no peak after the void volume. Presence of endothelin, a potent growth factor, in saliva and salivary gland points to a role in maintaining the integrity of the oral and gastrointestinal tract mucosa.