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Title Insulin binding sites in various segments of the rabbit nephron
Creator/Author Nakamura, R. ; Emmanouel, D.S. ; Katz, A.I.
Publication Date1983 Jul 01
OSTI IdentifierOSTI ID: 5544893
Other Number(s)CODEN: JCINA
Resource TypeJournal Article
Resource RelationJ. Clin. Invest. ; Vol/Issue: 72:1
Research OrgDepartment of Medicine, University of Chicago, Pritzker School of Medicine, Illinois
Subject560172 -- Radiation Effects-- Nuclide Kinetics & Toxicology-- Animals-- (-1987); ;INSULIN-- LABELLING;INSULIN-- RECEPTORS;LABELLED COMPOUNDS-- CHEMICAL PREPARATION;TUBULES-- RECEPTORS; ELECTROLYTES;IODINE 125;RABBITS;RADIOCHEMISTRY;TRACER TECHNIQUES
Related SubjectANIMALS;BETA DECAY RADIOISOTOPES;BODY;CHEMISTRY;DAYS LIVING RADIOISOTOPES;ELECTRON CAPTURE RADIOISOTOPES;HORMONES;INTERMEDIATE MASS NUCLEI;IODINE ISOTOPES;ISOTOPE APPLICATIONS;ISOTOPES;KIDNEYS;MAMMALS;NUCLEI;ODD-EVEN NUCLEI;ORGANS;PEPTIDE HORMONES;RADIOISOTOPES;SYNTHESIS;VERTEBRATES
Description/Abstract Insulin binds specifically to basolateral renal cortical membranes and modifies tubular electrolyte transport, but the target sites of this hormone in the nephron have not been identified.^Using a microassay that permits measurement of hormone binding in discrete tubule segments we have determined the binding sites of /sup 125/I-insulin along the rabbit nephron.^Assays were performed under conditions that minimize insulin degradation, and specific binding was measured as the difference between /sup 125/I-insulin bound in the presence or absence of excess (10(-5) M) unlabeled hormone.^Insulin monoiodinated in position A14 was used in all assays.^Specific insulin binding (attomol . cm-1 +/- SE) was highest in the distal convoluted tubule (180.5 +/- 15.0) and medullary thick ascending limb of Henle`s loop (132.9 +/- 14.6), followed by the proximal convoluted and straight tubule.^When expressed per milligram protein, insulin binding capacity was highest along the entire thick ascending limb (medullary and cortical portions) and the distal convoluted tubule, i.e., the ``diluting segment`` (congruent to 10(-13) mol . mg protein-1), and was lower (congruent to 4 X 10(-14) mol . mg protein-1), and remarkably similar, in all other nephron segments.^Binding specificity was verified in competition studies with unlabeled insulin, insulin analogues (proinsulin and desoctapeptide insulin), and unrelated hormones (glucagon, 1-34 parathyroid hormone, prolactin, follicle-stimulating hormone).^In addition, serum containing antiinsulin receptor antibody from two patients with type B insulin resistance syndrome markedly inhibited insulin binding to isolated tubules.^Whether calculated per unit tubule length or protein content, insulin binding is highest in the thick ascending limb and the distal convoluted tubule, the same nephron sites where a regulatory role in sodium transport has been postulated for this hormone.
Country of PublicationUnited States
LanguageEnglish
FormatPages: 388-392
System Entry Date2001 May 13

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