Maternal insulin and placental 3-O-methyl glucose transport.
The effects of insulin in the maternal circulation on the placental clearance of 3-O-methyl glucose were investigated in 7 animals in the presence of a constant maternal glucose concentration. While maternal insulin concentration changed from 12 +/- 4 to 175 +/- 33 mu Units/ml, the placental clearance remained constant at 16.2 +/- 1.2 (control) and 15 +/- 1.3 ml/min per kg fetus under the influence of the insulin. To test the secondary hypothesis that in the control condition the hexose transport system was saturated, we performed a further series of experiments in 6 fasted animals. In these animals the control maternal plasma insulin concentration was 2 +/- 0.3 mu Units/ml and after the infusion of insulin it increased to 562 +/- 26 mu Units/ml. Under conditions of constant maternal and fetal plasma glucose concentrations, this massive elevation of plasma insulin did not change the placental clearance of 3MeG which was 15.2 +/- 1.6 in the control condition and 13.3 +/- ml/min per kg under the influence of high insulin. We conclude that maternal insulin ranging from 2 mu Units/ml to supraphysiologic doses does not effect a physiologically significant change in placental hexose transfer. Placental glucose transfer can probably therefore, be changed only be changing the concentration of glucose in the maternal and fetal plasma.
D019325:3-O-Methylglucose; D000818:Animals; D001692:Biological Transport; D001786:Blood Glucose / Q000378:metabolism; D005215:Fasting; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D007328:Insulin / Q000097:blood*; D008757:Methylglucosides / Q000378:metabolism*; D008759:Methylglycosides / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood*; D012756:Sheep
D001786:Blood Glucose; D007328:Insulin; D008757:Methylglucosides; D008759:Methylglycosides; D019325:3-O-Methylglucose