Insulin-like growth factors in amniotic fluid.
The concentrations of insulin-like growth factors I and II (IGF-I and IGF-II) in amniotic fluid were determined by specific immunoassays in 58 women. IGF-I concentrations were constant throughout gestation at approximately 20 ng/ml; the mean IGF-II concentration was 114 +/- 13 (+/- SE) ng/ml at the earliest period of gestation studied and remained unchanged at 26 to 33 weeks despite a greater than 50% decrease in amniotic fluid total protein. A precipitous decrease in IGF-II concentration occurred at term which was not explainable by alterations in total amniotic fluid protein concentration. The concentrations of IGF-I and IGF-II in amniotic fluid did not correlate with concentrations of these factors in maternal serum (r = 0.08 and 0.09, respectively). [125I]IGF-I and [125I]IGF-II, after incubation with amniotic fluid, bound to a 40-45 K protein (or proteins). A carrier protein of greater mol wt, as in serum, was not detected. These findings indicate that there is dynamic control of IGF in amniotic fluid during normal pregnancy.
D000653:Amniotic Fluid / Q000032:analysis*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007328:Insulin / Q000032:analysis*; D010455:Peptides / Q000032:analysis*; D011247:Pregnancy; D011485:Protein Binding; D013002:Somatomedins / Q000032:analysis*
D007328:Insulin; D010455:Peptides; D013002:Somatomedins