[In vitro effects of anesthetics on hydrogen peroxide generating system of the thyroid gland]

Effects of anesthetics on thyroidal hydrogen peroxide generating system was studied using porcine thyroid follicles. This system is indispensable in thyroid hormone synthesis and seems also to play an important role in regulation of thyroid hormone release. The results indicated that H2O2 generation was controlled by Ca2+ ion mobilization and protein kinase-C linked signal transduction system. It was also demonstrated that thiopental, halothane, and enflurane had inhibitory effects on H2O2 generation system in thyroid follicle cells, and 50% inhibitory concentrations (IC50) of each anesthetic drug were 60 microM, 2.5% and 4.0%, respectively. Other anesthetic agents, such as local anesthetics and major tranquilizers did not show any inhibitory effects on porcine thyroid peroxidase activity as well as on the regulation of thyroid hormone release. Other than inhaled anesthetic agents, thiopental only is thought to have an antithyroid effects in clinical situation.