title: Interaction of steroids with the transport system of glucose in human erythrocytes.
abstract: Steroids inhibit the exchange transport of glucose in human erythrocytes. The extent of inhibition is roughly correlated to the affinity of the steroids to the membrane lipids. All C-21-steroids tested show a competitive inhibition while the C-19-steriods show different types of inhibition. 5Beta-androstane-3,17-dione acts as a competitive inhibitor. The inhibition by testosterone is of mixed type, while with androst-4-ene-3,17-dione and 5alpha-androstane-3,17-dione a non-competitive inhibition is observed. In this case two inhibitor molecules can be bound per transport molecule. The "non-competitive" inhibitors compete also to some extent with the glucose binding. This effect, however, is at high inhibitor concentrations masked by the more powerful non-competitive inhibition. Competitive and non-competitive inhibitors compete with each other. The structural requirements for the different types of inhibition are discussed.
mesh_terms: D015068:17-Ketosteroids / Q000494:pharmacology*; D000450:Aldosterone / Q000494:pharmacology; D000731:Androstanes / Q000494:pharmacology*; D000735:Androstenedione / Q000494:pharmacology; D001665:Binding Sites; D001667:Binding, Competitive; D001693:Biological Transport, Active / Q000187:drug effects; D003345:Corticosterone / Q000494:pharmacology; D003348:Cortisone / Q000494:pharmacology; D003350:Cortodoxone / Q000494:pharmacology; D004912:Erythrocytes / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology; D007700:Kinetics; D011283:Pregnenes / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013739:Testosterone / Q000494:pharmacology
chemical_list: D015068:17-Ketosteroids; D000731:Androstanes; D011283:Pregnenes; D013739:Testosterone; D000735:Androstenedione; D000450:Aldosterone; D005947:Glucose; D003348:Cortisone; D003345:Corticosterone; D003350:Cortodoxone; D006854:Hydrocortisone