EFFECT OF LOCAL-ANESTHETICS ON ACCESSIBILITY AND THERMAL-STABILITY OFTHE RAT OVARIAN LH HCG RECEPTOR/

Perturbation of rat ovarian membranes induced by local anesthetics alt ered the accessibility and thermal stability of the LH/hCG receptor. I ncubation of ovarian membranes with tetracaine and benzyl alcohol resu lted in a dose-dependent loss of binding activity of the LH/hCG recept or. Possible structure-functional properties of the receptor in membra nes treated with local anesthetics were analyzed by the thermal pertur bation technique. The heat inactivation profile of the LH/hCG binding sites in 10 mM tetracaine and 20 mM benzyl alcohol treated membranes w as shifted to lower temperatures of about 15 degrees C and 4 degrees C (T-50 values), respectively. The thermal stability of the receptor de creased with an increasing concentration of the local anesthetics. The rmal destabilization of the LH/hCG receptor induced by the action of t etracaine was higher at pH 9.5 than at pH 5.5. Treatment of ovarian me mbranes with 5 mM tetracaine modified and with 20 mM benzyl alcohol fa iled to change the quenching of protein fluorescence, characteristic f or control membranes. Incubation of ovarian membranes with tetracaine and benzyl alcohol increased the membrane lipid fluidity, as determine d by fluorescence polarization of the 1,6-diphenyl-1,3,5-hexatriene pr obe (DPH).