HYPOTHYROIDISM RENDERS LIVER-MITOCHONDRIA RESISTANT TO THE OPENING OFMEMBRANE-PERMEABILITY TRANSITION PORE

Membrane permeability was examined in liver mitochondria isolated from hypothyroid rats. It was found that such a thyroid status provides su bstantial protection from membrane leakiness as induced by Ca2+ loadin g. Thus, these mitochondria are less prone to undergoing permeability transition than mitochondria from euthyroid rats. The above conclusion was reached on the basis of the following two facts: (1) hypothyroid mitochondria are not strictly dependent on the addition of ADP to reta in high matrix Ca2+ concentrations, and (2) carboxyatractyloside, anti mycin A or carbonyl cyanide-m-chlorophenyl hydrazone failed to promote Ca2+ afflux. We discuss the possible relevance of the low content of membrane cardiolipin as well as the low expression of the adenine nucl eotide translocase as responsible for the resistance to membrane damag e. (C) 1998 Elsevier Science B.V. All rights reserved.