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Updated: Oct 9, 2026

Combined Intravital Microscopy and Contrast-enhanced Ultrasonography of the Mouse Hindlimb to Study Insulin-induced Vasodilation and Muscle Perfusion
08:22

Combined Intravital Microscopy and Contrast-enhanced Ultrasonography of the Mouse Hindlimb to Study Insulin-induced Vasodilation and Muscle Perfusion

Published on: March 20, 2017

Insulin and placenta: degradation and stabilization, binding to microvillous membrane receptors, and amino acid

R B Steel, J D Mosley, C H Smith

    American Journal of Obstetrics and Gynecology
    |October 15, 1979
    PubMed

    Human placenta possesses insulin receptors, yet whether insulin affects uptake of substrate or other placental functions is still controversial. A potential problem in the study of this issue is degradation of insulin by placental tissue. We found insulin degradation to be rapid and temperature dependent. At 10 mU/ml and 37 degrees C, 40% became trichloroacetic acid soluble within 15 minutes. Degradation was decreased by preincubation of tissue, followed by change of medium and by addition of 0.5% to 2.0% bovine albumin. Receptor assay with isolated microvillous membrane, which bound insulin with the characteristics of known target tissues, demonstrated biologically active insulin (5 to 6 mU/ml) to persist under incubation conditions. The presence of insulin did not influence the uptake of amino acids by the three neutral amino acid transport systems of the human placenta. Thus the transport of an essential fetal nutrient is is apparently independent of fluctuations in maternal insulin with dietary carbohydrate intake and disease.

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