Gastric mucin secretion from cultured rat epithelial cells

In order to establish the measurement of gastric mucin secreted from cultured mucous cells, rat gastric mucin was purified from secreted mucus with Sepharose CL-4B column chromatography. Gastric mucin was measured by dot blot analysis using an enzyme-linked lectin (soybean agglutinin) assay in a good concentration-dependent manner. Surface epithelial cells were dispersed by limited digestion of a rat everted stomach and collected by density gradient centrifugation with Percoll. These cells were inoculated onto gelled collagen dishes, then cultured in a medium supplemented with 10% fetal calf serum under a 5% CO2 atmosphere in air. Changing the medium after a 2-d culture, the cells were cultured for another 3 d. During the culture, the numbers of cells each day were almost equal, but mucin contents in the cells increased, and then dropped at day 5 after inoculation. At that time, the edge of the cell layer peeled off and the cells adhered to each other. Using 2-d cultured cells, the effects of some secretagogues on mucin secretion were investigated. Carbachol, secretin, CCK-8 and prostaglandin E2 (PGE2) strongly stimulated mucin secretion, and gastrin I weakly did. However, histamine offered no stimulation.