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Metiamide: more than an H2-receptor antagonist
The American Journal of Digestive Diseases
|February 1, 1978
Summary
Metiamide effectively inhibits gastric acid secretion stimulated by various agents, including those acting intracellularly. This histamine H2 receptor antagonist also increases calcium influx into parietal cells, suggesting a novel inhibition mechanism.
Area of Science:
- Gastroenterology
- Pharmacology
- Cell Physiology
Background:
- Gastric acid secretion is a complex process regulated by various signaling pathways.
- Histamine H2 receptor antagonists are key in managing acid-related disorders.
- Understanding the precise cellular mechanisms of these antagonists is crucial for therapeutic development.
Purpose of the Study:
- To investigate the inhibitory effects of metiamide on gastric acid secretion.
- To explore the impact of metiamide on calcium uptake in gastric parietal cells.
- To elucidate the cellular site of action for metiamide beyond the histamine H2 receptor.
Main Methods:
- Experiments were conducted on isolated frog gastric mucosa.
- Metiamide's effects were assessed alone and with histamine, pentagastrin, aminophylline, and dibutyryl cyclic AMP (db cAMP).
- Acid secretion and calcium uptake were measured to quantify metiamide's impact.
Main Results:
- Metiamide demonstrated inhibitory effects on all tested stimulants of acid secretion.
- The inhibition extended to dibutyryl cyclic AMP (db cAMP), indicating an intracellular site of action.
- Metiamide was observed to increase calcium influx into parietal cells.
Conclusions:
- Metiamide inhibits gastric acid secretion by acting intracellularly, downstream of the adenylate cyclase complex.
- The observed increase in calcium influx suggests a potential secondary mechanism of acid secretion inhibition by metiamide.
- These findings provide deeper insights into the pharmacological actions of histamine H2 receptor antagonists.