Alterations in rat intestinal mucin patterns following luminal infusion of acetylsalicylic acid and prostaglandin derivatives.

The secretion of gastrointestinal mucin and/or the formation of mucoid caps have been implicated in cytoprotective or repair mechanisms related to mucosal injury models. In this study, rats were treated with acetylsalicylic acid (ASA) or prostaglandins (PG), and their effects on the synthesis and secretion of small intestinal mucin were examined. A newly developed polyclonal antibody to rat intestinal mucin was used for immunoassay of rat intestinal luminal and tissue mucin. The mucin antigen source was obtained by vacuum aspiration of luminal mucus. A high-molecular-weight glycoprotein (2 x 10(6) Da) fraction injected into rabbits produced a primary mucin antibody. A sensitive and quantitative enzyme-linked immunosorbent assay (ELISA) was developed that yielded a highly reproducible and linear response with mucin aliquots containing 0-20 ng of protein/ml. Incorporation of the plasma tracers ([3H]glucose and [35S]sodium sulfate) into mucin derived from hexadecyltrimethylammonium bromide precipitation after treatment with ASA (100 mg/kg body wt) decreased, although administration of dimethylprostaglandin E2 (100 micrograms/kg body wt) significantly increased the specific tracer incorporation values for the sialomucin and sulfomucin indices in luminal mucin fractions. The immunoassay data pattern for the ELISA technique was virtually identical to the results of the radiolabeled tracer method obtained for the same pharmacologic treatments. These experiments demonstrate that the estimation of synthesized mucin (tissue source) or secreted mucin (luminal source) as determined by the ELISA technique is similar to that obtained by the time-consuming and labor-intensive tracer incorporation methodology.