Alkaline phosphatase isoenzymes in intestinal metaplasia and carcinoma of rat stomach induced by N-methyl-N'-nitro-N-nitrosoguanidine.

Intestinal metaplasia and carcinoma of the stomach were produced in Wistar strain rats by oral administration of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Alkaline phosphatase (AlP) isoenzymes of tissues from intestinal metaplastic mucosa and carcinoma of the stomach were studied. The ALP activity from all carcinoma tissues was several times higher than that of the surrounding gastric mucosa, and two of the tissues has over 100 times higher activity. An AlP zymogram from carcinoma tissues of the stomach showed one broad active band on 5% polyacrylamide-gel disc electrophoresis. This band was separated into 2 sharp active bands after treatment with neuraminidase: A-band (Rf = 19%) and B-band (Rf = 32%). From the enzymological and immunological study, B-band had properties similar to those of AlP isoenzyme from the intestinal metaplastic mucosa of the stomach, as well as intestinal AlP isoenzyme, while A-band had different ones. Anm AlP zymogram from glandular mucosa of the stomach showed 2 types of active band (A and B band) after treatment with neuraminidase, which were identical with those appearing in carcinoma tissues. The properties of AlP isoenzyme from the intestinal metaplastic mucosa of rat stomach induced by MNNG were similar to those of humans, and the carcinoma tissues of rat stomach were suspected of producing high amounts of AlP, especially the intestinal-type AlP isoenzyme.