[Effect of antioxidants and complexons on mitochondrial swelling induced by thyroxine]

The rate of thyroxin-induced swelling of rat liver mitochondria depended but little on the cation compositions of the medium (KCl, NaCl or choline chloride), this indicating that the enhancement of mitochondrial membrane permeability for cations in the presence of thyroxin was of negligible selectivity. The antioxidants alpha-tocopherol and beta-ionol in concentrations completely inhibiting the lipid perioxidation failed to affect the thyroxin-induced mitochondrial swelling; hence the latter could not be attributed to the lipoperoxidation. The kinetics of the swelling and the fact of its inhibition by EGTA imply the necessity of calcium ions in the activation of the process and make possible a postulation that the thyroxin-based mitochondrial swelling was based on the process of activation of the membrane phospholipase in these organellae.