Einfluß verschiedener Medikamente auf die Bindung von Schilddrüsenhormonen an Lebermitochondrien / Influence of Various Drugs on the Adsorption of Thyroid Hormones to Liver Mitochondria

1. [ I] ʟ-thyroxine (T ) or [ I] ʟ-triiodothyronine (T ) was added in 50 pᴍ - 25 nᴍ and 26 pᴍ -132 nᴍ concentrations to suspensions of rat liver mitochondria. In distribution equilibria between soluble proteins and mitochondria the adsorption of the thyroid hormones to the mito­ chondria followed an approximately linear function when the radioactive hormones were added within the range of physiological concentrations. At identical protein concentrations T was ad­sorbed to the mitochondria one tenth more strongly than T when neither serum proteins nor cell sap had been added. The adsorption of both T and T to mitochondria and soluble proteins is reversible. The distribution of the thyroid hormones between organelles and soluble proteins depends on the ratio of the protein concentration in the sedimented mitochondria to the protein concentration in the supernate after centrifugation. The desorption of T and T from the mito­ chondria by soluble proteins, however, represents no linear function. 2. The distribution equilibria of simultaneously added I -T and I -T can be shifted by certain drugs. Chlorpromazin and dinitrophenol displaced the thyroid hormones from their binding to soluble proteins onto the mitochondria. Vice versa, phenylbutazone, phenytoin, brom-sulfalein and silymarin displaced the hormones from the mitochondria more strongly than from soluble proteins. Sodium oleate displaced the hormones in both directions. Minor shifting effects or none at all could be detected when several other drugs were used. The described procedure apparently yields new information on some effects of drug action