[Triiodothyronine binding and norepinephrine uptake in the heart and liver]

Administration of norepinephrine to thyroidectomized rats activates sharply the [125I]triiodothyronine binding by heart mitochondria and liver nuclei. Epinephrine stimulates the binding by the heart mitochondria and decreases the intensity of this process in the liver and heart nuclei and liver mitochondria As compared to norepinephrine, adrenoxyl is weaker in activation of [125I] triiodothyronine binding by the heart mitochondria and stronger in intensification of binding by the liver nuclei. Physiological concentrations of thyroxine like adrenoxyl administered to intact animals 2h before investigations intensify the uptake of [3H] norepinephrine by sections of the auricles, myocardium and liver. Hyperthyroidization induces contrary changes inthe uptake of [3H] norepinephrine. Norepinephrine administration decreases sharply the uptake of [3H] norepinephrine by sections of the auricles and myocardium. The blocking of beta-adrenoreceptors weakens the uptake.