Evaluation of murine placental degradation and transfer of (/sup 125/I)iodo-epidermal growth factor

Journal Article · Sun Mar 01 04:00:00 EST 1987 · Endocrinology; (United States)

OSTI ID:6937452

DiAugustine, R P; Rosch, M J; Lannon, D E; Walker, M P; Pratt, R M

Since epidermal growth factor (EGF) has been postulated to play a role in embryonic and fetal growth, a study was undertaken to assess the placental degradation and transfer of maternally administered EGF. Approximately 5 ng of purified (/sup 125/I)iodo-EGF were injected iv into day 10, day 13, or day 17 pregnant CD-1 mice; radioactivity in plasma, placentas, and conceptuses was measured up to 2 h after injection. The time course analysis revealed an initial rapid decline in total plasma radioactivity followed by an increase that was maximal by approximately 30 min. Gel filtration (G-15, G-50) chromatography of plasma revealed that by 5 min, radioactivity was associated with free /sup 125/I and with material much larger than EGF. No apparent degradation of (/sup 125/I)iodo-EGF occurred after direct incubation with maternal plasma. Placental radioactivity had an initial phase of decay between 1 and 5 min followed by an increase that became maximal between 30 and 60 min. Extracts of placentas made with 4 M urea in 0.2 M Tris-HCl, pH 8.0, and taken 1-30 min after injection revealed radioactivity coeluting predominantly with (/sup 125/I)iodo-EGF at 1 min but shifting to mostly free /sup 125/I by 30 min. Uptake of radioactivity by conceptuses was not evident until about 15 min, and only free /sup 125/I was detected in extracts; the same results were obtained when 5 micrograms unlabeled EGF were injected simultaneously with (/sup 125/I)iodo-EGF. Incubation of placental mince with (/sup 125/I)iodo-EGF yielded (/sup 125/I)MIT as the apparent major radioactive degradation product. Formation of (/sup 125/I)MIT in vitro was both time- and temperature-dependent. At 37 C, marked formation of (/sup 125/I)MIT was observed; at 22 C, only a negligible amount was formed after incubation of mince with (/sup 125/I)iodo-EGF for 60 min. Incubation of (/sup 125/I)iodo-EGF with kidney mince yielded predominantly free /sup 125/I.

• Research Organization: National Institute of Environmental Health Sciences, Research Triangle Park, NC
• OSTI ID: 6937452
• Journal Information: Endocrinology; (United States), Journal Name: Endocrinology; (United States) Vol. 3; ISSN ENDOA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL GROWTH
ANIMALS
BETA DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BLOOD PLASMA
BODY FLUIDS
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
FETAL MEMBRANES
FETUSES
GROWTH
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
LABELLED COMPOUNDS
MAMMALS
MATERIALS
MEMBRANE TRANSPORT
MEMBRANES
MICE
NUCLEI
ODD-EVEN NUCLEI
PLACENTA
PREGNANCY
RADIOISOTOPES
RODENTS
SEPARATION PROCESSES
VERTEBRATES