Mucin is a critical component of the protective layer secreted by gastrointestinal mucous cells. A detailed understanding of the molecular processing of gastric mucin and the physiology of its secretion has been limited by the lack of an adequate model for their study. We have developed a primary culture system of canine gastric mucous cells that has permitted us to study their synthetic and secretory functions. It was found that [3H]glucosamine used for metabolic labeling studies was incorporated into both mucin and lipid components of gastric mucus. To measure mucin with this model, a new immunoassay was developed to quantitate canine gastric mucin. Mucin was purified from the canine stomach, a polyclonal antibody was generated, and an enzyme-linked immunosorbent assay for gastric mucin was established. Mast cells were frequent contaminants of the gastric mucous cell preparation, and two methods were developed to limit their contamination. A new culture system has been developed for the study of gastric mucous cells. These cells synthesize and secrete both mucin and phospholipids. This system will permit us to study the molecular processing of mucin and the physiology of its production and release.
