Abstract
Summary
The effects of tryptophan and its metabolites were studied to determine whether the known inhibiting effect of tryptophan on emptying was due to local or systemic effects or due to tryptophan metabolites. In five dogs with chronic gastric fistulas, instillation of 300 ml of dl-kynurenine (5 mM), 5-hydroxytryptophan (5 mM), or 5-hydroxytryptamine (20 mM) into the gut did not slow gastric emptying. Furthermore, iv infusion of l-tryptophan (5, 20, 50 mM), dl-kynurenine (2, 5, 10 mM), 5-hydroxytryptamine (2 mM, 10 mM), and 3-indolepyruvic acid (2, 5, 10 mM) also did not slow gastric emptying.
These studies indicate that tryptophan slows gastric emptying by exciting a receptor in the gut and not by a direct effect on the stomach or brain or via its major metabolites.
This work was supported by Grant AM 15886 from the National Institutes of Health and Veterans Administration Research Funds.
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