Interaction of physalaemin, substance P, and eledoisin with specific membrane receptors on pancreatic acinar cells.

Abstract

We have prepared '251-labeled physalaemin and have examined the kinetics, stoichiometry, and chemical specificity with which the labeled peptide binds to dispersed acini from guinea pig pancreas. Binding of '25I-labeled physalaemin was saturable, temperature-ependent, and reversible and reflected interaction of the labeled peptide with We (1, 2) and others (3, 4) have found that peptides isolated from amphibian skin (caerulein, bombesin, litorin, and physalaemin) as well as eledoisin, a peptide isolated from the salivary gland of a Mediterranean octopod,t produce changes in the function of pancreatic acinar cells similar to those caused by muscarinic cholinergic agents and cholecystokinin (CCK). In pancreatic fragments as well as dispersed acinar cells, each of these amphibian peptides increases amylase secretion, cellular cyclic GMP, and outflux of exchangeable cellular calcium but does not alter cellular cyclic AMP (1). These effects of amphibian peptides are not inhibited by atropine (1, 4), and therefore are not mediated by muscarinic cholinergic receptors. The effects of caerulein appear to be mediated by receptors that also interact with CCK because the actions of caerulein and CCK, but not those of other pancreatic secretagogues, can be inhibited competitively by dibutyryl cyclic GMP (5). The effects of bombesin and litorin on pancreatic acinar cells appear to be mediated by a common receptor that does not interact with other secretagogues. Binding of 125I-labeled [Tyr4] bombesin (125I-[Tyr4]bombesin) to pancreatic acini in vitro can be inhibited by bombesin and litorin but not by other secretagogues (6) and there is a close correlation between the abilities of bombesin and litorin to inhibit binding of 1251-[Tyr4]bombesin and their abilities to alter the function of pancreatic acini (6). Because physalaemin and eledoisin have similar COOHterminal amino acid sequences and do not interact with receptors for other pancreatic secretagogues, we have proposed (1) that these peptides might interact with a common class of receptors.To explore further the interaction of physalaemin and structurally similar peptides with pancreatic acini, we have prepared 125I-labeled physalaemin (125I-physalaemin) and have examined its ability to bind to dispersed pancreatic acini. We have also explored the abilities of various peptides to inhibit this binding, and the relationship between a peptide's ability to inhibit binding of 125I-physalaemin and its ability to alter acinar cell function. Our results indicate that pancreatic acini possess a single class of receptors that interact reversibly with physalaemin, eledoisin, and substance P and that occupation of approximately 45% of these receptors is sufficient to cause a maximal change in acinar cell function.MATERIALS AND METHODS Materials. Male guinea pigs (175-225 g) were obtained from the Small Animals Section, Veterinary Resources Branch, National Institutes of Health. Hepes and cyclic somatostatin were obtained from Calbiochem; synthetic human gastrin was from ...

Specific Binding of a 125I‐Substance P Derivative to Rat Brain Synaptosomes

“…It was also temperature dependent, since the initial rate of the labeled ligand association was accelerated at 37°C whereas maximal binding was markedly reduced at 4°C. Similar results were obtained by Sjiidin et al (1980) and Jensen and Gardner (1979) ( 1251-Tyr*)substance P and of 12sI-physalaemin to pancreatic acinar cells normally seen at 20°C. As shown by kinetic studies, equilibrium for IZsI-BHSP specific binding to synaptosomes was rapidly reached at 20°C (5 min), and this binding was reversible.…”

“…As already noted, this could be attributed to a modification with age of substance P receptor properties, their sensitivity being decreased when substance P neurons are fully developed and functionally in contact with their target cells. Confirming results obtained in other binding studies on substance P receptors (Jensen and Gardner, 1979;Hanley et al, 1980b;Liang and Cascieri, 1981), several peptides unrelated to substance P did not inhibit l"-BHSP binding to synaptosomes.…”

“…Dispersed cells or membrane preparations were used for this purpose. Specific high-affinity binding sites were found on pancreatic or parotid acinar cells using l z 5 Iphysalaemin (Jensen and Gardner, 1979;Putney et al, 1980), (1251-TyrR)substance P (Sjodin et al, 1980), and the 1251-labeled Bolton and Hunter derivative of substance P ( lZ5I-BHSP) as ligands. Recently, a specific binding of 1251-BHSP to mesencephalic cultures prepared from embryonic mouse brain was demonstrated in our laboratory (Beaujouan et al, 1982).…”

Expression of NK-1 and NK-3 tachykinin receptors in pancreatic acinar cells after acute experimental pancreatitis in rats

“…TKs acting on NK-1 and NK-2 receptors have been reported to stimulate in vitro pancreatic amylase secretion (12-14, 16, 20, 33), and NK-1 and NK-2 receptors have been detected in the pancreatic acinar cells of guinea pig and mouse (6,11,29,30,32). No information is available on whether acinar cells in the pancreas of these and other animal species express the NK-3 receptor, and little is known on the effects of NK-3 receptor agonists on pancreatic exocrine secretion (7,12,18,20,33). In our recent studies, using in vitro functional (19) and immunocytochemical (4) assays, we reported that guinea pig pancreatic acinar cells contain homogeneously distributed NK-1 and NK-3 receptors that mediate a direct stimulatory action on amylase release.…”

The EFFECTS OF SUBSTANCE P AND RELATED PEPTIDES ON Α‐AMYLASE RELEASE FROM RAT PAROTID GLAND SLICES

“…The relative potencies of tachykinins have been proposed as a means of discriminating between types of substance P receptor (Erspamer etal., 1980;Lee, 1981). For example, whilst eledoisin is equipotent with substance P in eliciting amylase release from parotid slices, it is about 1/50th as potent as substance P in producing the same response from pancreatic acinar cells (Jensen & Gardner, 1979). It may be that the amylase response to substance Prelated peptides is composed of more than one type of pharmacological receptor.…”