[Uptake of 125I-triiodothyronine by the thyroid gland: effect of adrenergic agents and low temperatures].

A study was made of the binding of 125I-triiodothyronine with the sections, nuclei and mitochondria of the euthyroid thyroid under the conditions of adding adrenergic agents, cooling to 0 degree C and freezing to--196 degrees C. It was noted that 125I-T3 got no less with adding unlabeled T3 and thyroxine that might suggest the unsaturated nature of the process. Among the studied adrenergic agents (noradrenaline, neoepinephrine, propranolol, pyrroxane in the concentration of 1 X 10(-4) M) noradrenaline only influenced this process. It stimulated binding and pyrroxane inhibited it. 125I-T3 binding got less at 0 degree C, after freezing to--196 degrees C the preservation of the basal activity of the process and disappearance of the noradrenaline stimulating effect were noted. The results obtained do not confirm assumptions as to the mechanism of thyroid autoregulation function with T3 by the short feedback type.