In vivo effects of five secretin analogs on fluid and potassium secretion from the rat pancreas

1. Vasoactive intestinal peptide (VIP) receptors were identified in crude rat hepatic membranes by '^^Ilabelled VIP binding and by the ability of VIP to stimulate adenylate cyclase activity. The specificity of thèse receptors was evaluated by the capacity of secretin, synthetic secretin analogues, and secretin fragments to inhibit '^^I labelled VIP binding and to stimulate adenylate cyclase. 2. The results were compatible with the existence of two classes of VIP binding sites that could be distinguished according to their affinity for VIP and their specificity. Highaffinity sites were more spécifie for VIP as secretin was 175 times less potent than VIP for récognition of thèse sites while being only 33 times less potent than VIP for récognition of lowaffinity sites. 3. Secretin analo gues, monosubstituted in position 2, 3, 4 or 6 were less potent than secretin for adenylate cyclase stimulation as well as for the récognition of the two classes of receptors. [Val^ jSecretin was more potent than secretin and appeared definitely more VIPlike than secretin; [Ala'*,Val']secretin and [DAla'',Val']secretin were equipotent to secretin. 4. The fragment secretin (727) was unable to recognize VIP receptors and to stimulate adenylate cyclase. The substituted fragment [Gln',Asn'^]secretin (527) recognized thèse receptors with weak potency but could net activate the enzyme.

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In vivo effects of five secretin analogs on fluid and potassium secretion from the rat pancreas

Cited by 4 publications

References 14 publications

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Binding of vasoactive intestinal peptide and its stimulation of adenylate cyclase through two classes of receptors in rat liver membranes effects of 12 secretin analogues and 2 secretin fragments

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