Abstract
We investigated the effect of tryptophan (Trp) on exocrine secretory function, using isolated rat pancreatic acini. Trp inhibited cholecystokinin-octapeptide (CCK-8)-stimulated amylase secretion, causing a downward shift in the dose-response curve. The inhibitory effect of Trp was dose-dependent and was observed only on the sustained secretion, there being no effect on the initial phase of amylase secretion. Trp (10mM) also inhibited amylase secretion in response to carbachol and bombesin, as well as fluoride, a potent activator of guanine-nucleotide binding proteins. Since Ca2+ influx is necessary for sustained secretion, we examined the effect of Trp on Ca2+ influx and efflux. Trp increased the CCK-8-stimulated Ca2+ influx rate without affecting Ca2+ efflux, suggesting that Trp elevates intracellular Ca2+ levels. Increasing intracellular Ca2+ levels with A23187 resulted in the inhibition of CCK-8-stimulated amylase secretion. These results indicate that Trp inhibits CCK-stimulated sustained amylase secretion, in part by increasing Ca2+ influx into acinar cells.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
