Action of antioxidants and chelating agents on thyroxine-induced swelling of mitochondria

The rate of swelling of rat liver mitochondria in the presence of thyroxine depended only a little on the cationic composition of the medium (KCl, NaCl, or choline chloride), which suggests an unselective increase in mitochondrial membrane permeability for cations in the presence of thyroxine. The antioxidant -tocopherol and -ionol, in concentrations completely suppressing peroxidation of lipids, did not affect thyroxine-induced swelling of the mitochondria, which is thus not connected with lipid peroxidation. The kinetics of swelling and its inhibition by the Ca-chelating agent EGTA are evidence that Ca²⁺ is essential for induction of this process. Thyroxine swelling of mitochondria is evidently based on activation of membrane phospholipase in these organelles.N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. N. Orekhovich.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 10, pp. 426–428, October, 1977