Phenol, A Potent Stimulator of Adenylate Cyclase in Human Thyroid Membranes

Abstract

Among several commercial hCG preparations tested for their ability to stimulate adenylate cyclase in a human thyroid particulate fraction, only a pharmaceutical preparation (APL) was active. Activity of this preparation was lost during dialysis, but could be restored fully by the addition of phenol and partially by the addition of benzyl alcohol, the two additives present in APL. Phenol itself (0.040–2.0 mg/ml) induced a potent, dose-dependent stimulation of adenylate cyclase activity in a human thyroid particulate fraction and was also active in plasma membranes from rat liver and kidney cortex. Phenol exerted a biphasic effect on [¹²⁵I]-bTSH binding to human thyroid membranes. Concentrations between 0.33 and 3.3 mg/ml were stimulatory to binding, while higher concentrations were inhibitory.