Abstract
With isolation, the parietal cell is removed from the effects of the many endogenous substances that may modulate its function in intact mucosa, even in the basal state. The isolated canine parietal cell responds to the major endogenous regulators of secretion: histamine, acetylcholine and gastrin. These agents act on specific receptors as evidenced by (1) the specificity of antagonists (H
2
antagonists, atropine, and dibutyryl cyclic GMP respectively), (2) the binding of radiolabelled ligands, and (3) the existence of separate second messenger systems (cyclic AMP for histamine, calcium influx for acetylcholine, and an unidentified mechanism for gastrin). Potentiating interactions, which occur between histamine and acetylcholine or histamine and gastrin, do not involve extra production of second messenger. When histamine and acetylcholine are given together, the amounts of cyclic AMP generated and of calcium entering the cell are not greater than when each is acting alone. The apparent non-specific effects of inhibitors acting
in vivo
, such as the inhibition of all forms of stimulation by H
2
antagonists, could reflect withdrawal of the potentiating action of the background histamine always present in the mucosa.
Subject
Industrial and Manufacturing Engineering,General Agricultural and Biological Sciences,General Business, Management and Accounting,Materials Science (miscellaneous),Business and International Management
Cited by
18 articles.
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