Gastrin

GASTRIN

Ⅰ．緒言

　Gastrinは1964年Gregory＆Tracyらによって始めて純粋に抽出されそのアミノ酸構造が明らかにされ，その全合成にも成功し，さらに生理的活性基（active site）であるC末端tetrapeptideが決定されるという画期的な業績が発表された．ここにいたってEdkins（1905年）以来，60年におよぶgastrinの歴史は新しい時代を迎えた．gastrinの持つ強力なしかも生理的な胃酸分泌刺激作用はhistamineに代る新しい胃酸分泌刺激剤として登揚し，またGastrinの持つ多方面にわたる生理作用は消化器疾患の治療に新しく導入されるであろう．またgastrinのbioassayあるいはimmunoassayが確立されるならば，生体内におけるgastrinの動態が明らかにされ，消化器疾患の病態生理の解明および診断に新しい分野が開拓されようとしている．著者は1965年以来鯨の胃のgastrinの研究に従事し，1967年gastrinのbioassay法を確立し現在手術胃材料よりgastrinの抽出量を測定し若干の知見を得，一方immunoassay法についても検討を重ねているので，この方面の解説を試みることにした．

Gastrin and Gastrone-like Substance extracted from Human Antral Mucosa

　Gregory and Tracy have described the isolation from hog antral mucosa of two heptadecapetide amides which are believed to represent the antral hormon gastrin. Also, Ghosh and Shild have isolated gastrin from the human antral mucosa and the sheep antral mucosa, and have elucidated their respective structures.

　The authors earlier extracted gastrin and gastrone-like substance (or gastric inhibitory substanee) from the whale by the method devised by Gregory and Tracy. Later, the authors also succeeded in extracting gastrin and gastrone-like substance from human and canine antral mucosa.

　It is considered clinically important to have succeeded in extracting from the human antral mucosa these two hormonal substances, which are antagonistic against gastrin secretion and motility.

　The bioassay of these two substances is discussed in the presnt report.

Results

　1) In the bioassay of gastrin, examination was made by the Shil's rat method with synthetic tetragastrin as the standard, in regard to its area of pH reduction. As a result, the measurement of the extracted gastrin was made possible by the four-point assay method.

　2) By this means, its was found that the activity of the gastrin extracted from the normal human antral mucosa is 1.56+-0.16 tetragastrin μg Eq/tissue extract mg and that the activity of the gastrin from the antral mucosa of the human stomach suffering from cancer is 0.54 tetragastrin μg Eq/tissue extract mg, much lower than the former case.

　3) It was found that the gastrin and the gastrone-like substance extracted simultaneously from the human antral mucosa are clearly antagonistic in their reactions to gastric secretion and motility.

　4) In the bioassay of the gastrone-like substance, the Shild's rat method was used instead of the Shay's rat method, which is considered rather inadequate in this case. It was found that the inhibitory percentage obtained by the use of the standard gastrin 30 minutes after the injection of gastrone is most suitable for the bioassav of the gastrone-like substance.