Comparison of (/sup 125/I)somatomedin A and (/sup 125/I)somatomedin C radioreceptor assays for somatomedin peptide content in whole and acid-chromatographed plasma

Journal Article · Fri Dec 01 04:00:00 EST 1978 · J. Clin. Endocrinol. Metab.; (United States)

DOI:https://doi.org/10.1210/jcem-47-6-1287· OSTI ID:5760864

Horner, J M; Liu, F; Hintz, R L

The placental membrane radioreceptor assay was used to measure the levels of somatomedin (SM) peptides in plasma. Displacement of both (/sup 125/I)somatomedin A ((/sup 125/I)SM-A) and (/sup 125/I)somatomedin C ((/sup 125/I)SM-C) by normal whole plasma, the peptide fraction of acid-chromatographed plasma, and a partially purified, insulin-free SM preparation were compared. The peptide fraction of plasma was isolated by acid chromatography over Sephadex G-50 in 0.25 M formic acid with a yield of greater than or equal to 90%, as determined by bioassay and (/sup 125/I)SM. In the case of (/sup 125/I)SM-A, the dose-response curves for whole plasma, acid-chromatographed plasma, and the standard SM preparation were parallel (P > 0.2). In contrast, for (/sup 125/I)SM-C, the dose-response curves for acid-chromatographed plasma and the purified SM preparation were parallel (P > 0.2), but both differed significantly from that of whole plasma (P < 0.001). In addition, there was less variability in the assay of acid-chromatographed plasma compared to whole plasma. The results indicate that radioreceptor assay of unextracted normal plasma using (/sup 125/I)SM-A is a valid measure of SM peptide concentration, while radioreceptor assay of unextracted normal plasma using (/sup 125/I)SM-C, in our hands, is not. Acid chromatography of plasma before its assay is an uncomplicated procedure which allows valid and precise measurement of SM peptide content using either (/sup 125/I)SM-A or (/sup 125/I)SM-C.

• Research Organization: Stanford Univ. School of Medicine, CA
• OSTI ID: 5760864
• Journal Information: J. Clin. Endocrinol. Metab.; (United States), Journal Name: J. Clin. Endocrinol. Metab.; (United States) Vol. 47:6; ISSN JCEMA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BETA DECAY RADIOISOTOPES
BIOASSAY
BIOLOGICAL MATERIALS
BLOOD
BLOOD PLASMA
BODY FLUIDS
CARBOXYLIC ACIDS
CHROMATOGRAPHY
COMPARATIVE EVALUATIONS
DAYS LIVING RADIOISOTOPES
DIAGNOSTIC TECHNIQUES
DOSE-RESPONSE RELATIONSHIPS
ELECTRON CAPTURE RADIOISOTOPES
FETAL MEMBRANES
FORMIC ACID
HORMONES
INSULIN
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
LABELLED COMPOUNDS
LIQUID COLUMN CHROMATOGRAPHY
MALES
MAMMALS
MEMBRANES
MONOCARBOXYLIC ACIDS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PH VALUE
PITUITARY HORMONES
PLACENTA
RADIOASSAY
RADIOISOTOPES
RATS
RODENTS
SEPARATION PROCESSES
STH
VERTEBRATES