title: Gastric inhibitory peptide, serotonin, and glucagon are unexpected chloride secretagogues in the rectal gland of the skate (Leucoraja erinacea).
abstract: Since the discovery of the rectal gland of the dogfish shark 50 years ago, experiments with this tissue have greatly aided our understanding of secondary active chloride secretion and the secretagogues responsible for this function. In contrast, very little is known about the rectal gland of skates. In the present experiments, we performed the first studies in the perfused rectal gland of the little skate (Leucoraja erinacea), an organ weighing less than one-tenth of the shark rectal gland. Our results indicate that the skate gland can be studied by modified perfusion techniques and in primary culture monolayers, and that secretion is blocked by the inhibitors of membrane proteins required for secondary active chloride secretion. Our major finding is that three G protein-coupled receptor agonists, the incretin gastric inhibitory polypeptide (GIP), also known as glucose-dependent insulinotropic peptide, as well as glucagon and serotonin, are unexpected potent chloride secretagogues in the skate but not the shark. Glucagon stimulated chloride secretion to a mean value of 1,661 ± 587 μeq·h(-1)·g(-1) and serotonin stimulated to 2,893 ± 699 μeq·h(-1)·g(-1). GIP stimulated chloride secretion to 3,733 ± 679 μeq·h(-1)·g(-1) and significantly increased tissue cAMP content compared with basal conditions. This is the first report of GIP functioning as a chloride secretagogue in any species or tissue.
authors.affiliation: Nephrology Division, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut;
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Kelley
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Decker
authors.forename: Patricio
authors.initials: P
authors.lastname: Silva
authors.forename: John N
authors.initials: JN
authors.lastname: Forrest
mesh_terms: D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D005749:Gastric Inhibitory Polypeptide / Q000494:pharmacology*; D005934:Glucagon / Q000494:pharmacology*; D008564:Membrane Potentials; D010477:Perfusion; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D012491:Salt Gland / Q000187:drug effects* / Q000378:metabolism; D012701:Serotonin / Q000494:pharmacology*; D012754:Sharks / Q000378:metabolism; D012860:Skates, Fish / Q000378:metabolism*; D049994:Sodium Potassium Chloride Symporter Inhibitors / Q000494:pharmacology; D028021:Sodium-Potassium-Chloride Symporters / Q000187:drug effects / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism; D013045:Species Specificity; D013997:Time Factors; D015854:Up-Regulation
chemical_list: D002712:Chlorides; D004791:Enzyme Inhibitors; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D049994:Sodium Potassium Chloride Symporter Inhibitors; D028021:Sodium-Potassium-Chloride Symporters; D012701:Serotonin; D005749:Gastric Inhibitory Polypeptide; D005934:Glucagon; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000254:Sodium-Potassium-Exchanging ATPase
keywords: GIP; cAMP; glucagon; little skate (Leucoraja erinacea); rectal gland; serotonin