The effect of temperature on the competitive inhibition of glucose transfer in human erythrocytes by phenolphthalein, phloretin and stilboestrol.
1. Phenolphthalein, like other diphenols, has been shown to be a competitive inhibitor of the facilitated transfer system for glucose in the human erythrocyte.2. The concentration producing 50% inhibition is lower at low temperatures and increases steadily over the temperature range 10-40 degrees C. An Arrhenius plot of the results gives a slope of 19,300 cal/mole.3. The effect of temperature on inhibition by phloretin and stilboestrol has also been studied. The temperature variation of the concentration of phloretin giving 50% inhibition is similar to that for phenolphthalein, but that for stilboestrol is much less.4. There is a high cell/medium distribution ratio for stilboestrol, and the possibility that this may affect the temperature dependence of the aqueous concentrations required to give 50% inhibition is discussed.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects*; D002247:Carbon Isotopes; D004054:Diethylstilbestrol / Q000378:metabolism / Q000494:pharmacology*; D004912:Erythrocytes / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006168:Guinea Pigs; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010635:Phenolphthaleins / Q000494:pharmacology*; D010693:Phloretin / Q000494:pharmacology; D010696:Phloroglucinol / Q000494:pharmacology*; D011427:Propiophenones / Q000494:pharmacology*; D013696:Temperature
D002247:Carbon Isotopes; D010635:Phenolphthaleins; D011427:Propiophenones; D004054:Diethylstilbestrol; D010696:Phloroglucinol; D005947:Glucose; D010693:Phloretin