PHARMACOLOGICAL REGULATION OF GASTRIC MUCOUS GLYCOPROTEIN-SECRETION

Gastric mucous glycoproteins (CMGs) are an important protective compon ent of the gastric 'mucus bicarbonate barrier'. The characterization o f drug effects on GMG metabolism is difficult because the quantificati on of GMGs poses analytical problems and because indirect drug effects (e.g, on other gastric secretory functions) can influence GMC metabol ism or quantification and thereby complicate the interpretation of in- vivo experiments. The use of suitable in-vitro systems, in particular of isolated gastric mucous cells, helped to resolve the latter problem and enabled the characterization of direct effects of prostaglandins, gastric acid secretagogues, peptide hormones, growth factors, adrenoc eptor agonists, and synthetic compounds (e.g. teprenone) on GMG metabo lism. Furthermore, from these experiments, evidence has accumulated th at the cyclic AMP system, the inositol trisphosphate/calcium/protein k inase C system and the cyclic GMP system are involved in the intracell ular transmission of drug effects on CMG metabolism.