title: Comparison of VIP-secretin receptors in rat and human lung.
abstract: The binding of 125I-VIP (Vasoactive Intestinal Peptide) to a crude particulate fraction from a rat lung was reversible and 125-I-VIP dissociation was accelerated by guanine triphosphate nucleotides. The relative potency of VIP and related peptides to compete with 125-VIP for binding was similar to their ability to stimulate adenylate cyclase in the same preparation. Dose-effect curves were compatible with the existence of two classes of VIP-receptors: a high-affinity type with equal affinity for VIP and [Val5] secretin, and a low-affinity type with affinity decreasing in the order VIP greater than [Val5] secretin greater than secretin. The response of a crude particulate adenylate cyclase preparation from human lung was also investigated. The biphasic pattern of adenylate cyclase stimulation by VIP suggested the presence of high- and low-affinity VIP receptors coupled to the enzyme. In addition, the stimulation of adenylate cyclase by secretin and [Val5] secretin was also biphasic, suggesting the coexistence of high- and low-affinity secretin receptors, Secretin (7-27) inhibited completely the secretin-stimulated activity operating through high-affinity secretion receptors, so that these receptors appear to be genuine secretin-preferring receptors.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000328:Adult; D000818:Animals; D001667:Binding, Competitive; D004789:Enzyme Activation / Q000187:drug effects; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006801:Humans; D008168:Lung / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011453:Prostaglandins / Q000494:pharmacology; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D011964:Receptors, Gastrointestinal Hormone; D018005:Receptors, Vasoactive Intestinal Peptide; D012633:Secretin / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000318:Adrenergic beta-Agonists; D011453:Prostaglandins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D011964:Receptors, Gastrointestinal Hormone; D018005:Receptors, Vasoactive Intestinal Peptide; C029937:secretin receptor; D012633:Secretin; D014660:Vasoactive Intestinal Peptide; D006160:Guanosine Triphosphate; D000262:Adenylyl Cyclases