Gastrin, inozivikanwawo se pepsin, ihomoni yemudumbu inonyanya kuvharwa neG masero egastric antrum uye duodenum uye inoita basa rakakosha mukugadzirisa basa rekugaya uye kuchengetedza chimiro chakasimba chegumbo rekudya. Gastrin inogona kukurudzira gastric acid secretion, kufambisa kukura kwegastrointestinal mucosal masero, uye kuvandudza hutano uye kugovera kweropa kwemucosa. Mumuviri wemunhu, inopfuura 95% yebiologically active gastrin is α-amidated gastrin, iyo inonyanya kuve nemaisomer maviri: G-17 uye G-34. G-17 inoratidza iyo yepamusoro-soro yemukati mumuviri wemunhu (inenge 80% ~ 90%). Secretion yeG-17 inodzorwa zvakasimba nepH kukosha kwegastric antrum uye inoratidza maitiro asina kunaka emhinduro inoenderana negastric acid.