Insulin radioreceptor assay for human erythrocytes. [/sup 125/I tracer technique]

Conference · Thu Sep 01 04:00:00 EDT 1977 · Clin. Chem.; (United States)

OSTI ID:7294577

Gambhir, K K; Archer, J A; Carter, L

Human erythrocytes have specific insulin receptors. Radioreceptor assay for the determination of insulin binding to these receptors is presented. After two passages over a Boyum-type gradient, erythrocytes from freshly collected heparinized blood were isolated and 3.5 x 10/sup 9/ erythrocytes per milliliter were incubated for 2.5 h in a modified pH 8.0 4-(2-hydroxyethyl)-1-piperazine ethane sulfonate buffer, iodinated insulin (80 pg/ml), and a range of unlabeled insulin concentrations(0 to 1 x 10/sup 5/ ng/ml). Incubation was terminated by pipetting 200 ..mu..l of the incubated suspension onto 200 ..mu..l of buffer and 200 ..mu..l of dibutyl phthalate in pre-chilled microcentrifuge tubes. After centrifugation, supernatant fluid was aspirated, leaving about 0.1 of the dibutyl phthalate on the cell pellets. Percentage of (/sup 125/I) insulin bound was determined after radioactivity of the cell pellets was measured in a gamma counter. Under these conditions 11 normal volunteers demonstrated a mean of 7.2 +- 0.44% insulin bound specifically to 3.5 x 10/sup 9/ cells. The nonspecific binding varied from 8 to 17% of the total insulin bound. Further, a linear increase of specific binding from 1.35 to 13.55% was observed when the cell concentration was increased from 0.72 to 7.2 x 10/sup 9/ cells per milliliter, respectively. Insulin, 100 ng/ml, from several animal species inhibited more than half of the binding of porcine /sup 125/I-labeled insulin. Bovine glucagon inhibited 9.8% and bovine somatotropin inhibited 1.1%, whereas desalanine-desasparagine insulin and human choriogonadotropin (10 int. units) did not inhibit binding of /sup 125/I-labeled insulin. For seven duplicates done on a single assay, the CV was 16.1%, whereas that for 11 assays done on different subjects and on different days was 10.7%. Receptor assays utilizing this technique thus have sufficient specificity and sensitivity to be used for further clinical diagnostic and investigative studies of insulin receptors on human erythrocytes.

• Research Organization: Howard Univ., Washington, DC
• OSTI ID: 7294577
• Conference Information: Journal Name: Clin. Chem.; (United States) Journal Volume: 23:9
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
BETA DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ERYTHROCYTES
HORMONES
INSULIN
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
PEPTIDE HORMONES
RADIOASSAY
RADIOISOTOPES
TRACER TECHNIQUES