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SPECIFIC BINDING SITES OF [~(3)]CORTISOL AND 〔~(3)H] DEXAMETHASONE IN RAT LIVER CELL MEMBRANE

Cheng Zhiping

Department of Physiology harbin Medical University , harbin 150086

Abstract

By using[IH〕 cortisol and〔3H〕 dexamathasone (DEX)，a class of specific binding sites of glucocorticoids (GC) in rat liver cell membrane was observed. These binding sites had saturability，high affinity and low capacity. The kinetic parameters of [3H] cortisol and [3H〕 DEX were:Kd=12. 84士6. 58 nmol/L (n=4) and 40. 27士23. 44 nmol/L (n=3) respectively;Bmax=2.57士1. 84 pmol/mg protein and 0. 64士0. 18 pmol/mg protein respectively (X士SE).The Kd obtained from the kinetic studies was corresponding to the results.of Scatchard analysis. Scatchard plots from the equilibrium experiments showed the straight line. The Hill coefficients were 0. 9880 and 0. 9990 respectively. The competitive displacement experiments indicated that cortisol possessed the higher specificity for the [3H ] cortisol binding sites than other tested steroids (prednisolone，progesterone，RU486，DEX).The competitive ability of cortisol was at least 40 folds higher than mentioned steroids. By means of autoradiography technique，the existence of[3H〕 cortisol labelled particles on the liver cell membrane was found.

Key words: elucocorticoids ; liver cell membrane;

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Citing This Article：

Cheng Zhiping. SPECIFIC BINDING SITES OF [~(3)]CORTISOL AND 〔~(3)H] DEXAMETHASONE IN RAT LIVER CELL MEMBRANE. Acta Physiol Sin 1994; 46 (5): (in Chinese with English abstract).