Studies of oxidative and phosphorylative systems in mitochondria. II. In vitro studies of the effects of various organic mercury compounds and heavy metals on rat-liver mitochondria.

Abstract

The effects of organic mercury compounds: methyl-, ethyl-, propyl-, butyl-, and phenylmercury, and of the heavy metals: Hg++, Pb++, Cd++, Cu++, Zn++, Co++, and Ni++, on oxidative phosphorylation were investigated with rat-liver mitochondria in vitro. At low concentrations of 10-6 to 10-5M both the organic mercury compounds and heavy metals tested had detrimental effects on mitochondrial functions accompanied by decreases in the P/O ratio. Of the organic mercury compounds tested, methylmercury showed unique results. When its concentration increased to a certain level, it restored respiration while strongly inhibiting phosphorylation. At some concentrations, organic mercury compounds and heavy metals produced basically the same effects, i.e., an uncoupling effect and the stimulation of ATP hydrolysis, resulting in the production of AMP. These results were the same as those obtained with DNP. The production of AMP was remarkable in every case when the inhibitors tested acted to lower the P/O ratio and to accelerate ATP hydrolysis. However, it is not clear how and why such a relatively large amount of AMP is produced.