Effects of Phosphate, Arsenate, and Other Substances on Swelling and Lipid Peroxide Formation When Mitochondria Are Treated with Oxidized and Reduced Glutathione.

As we have previously reported (1, 2) and as Neubert, Woj trzak, and Lehninger have confirmed (3), large amounts of lipid peroxide, as measured by the thiobarbit#uric acid color reaction (4), are formed during swelling and lysis of di1ut.e suspensions of liver mitochondria in the presence of oxidized and reduced glutathione (GSSG + GSH). This swelling has quite different characteristics from that produced by phosphate (2). Many substances inhibit swelling produced by GSSG + GSH (2, 5-7), but of special intrrcst arc effects seen with phosphate, arsenate, and thyrosinc. When phosphate or arsenate in rather low concentration is added with mixtures of GSSG and GSH, the phosphate-induced type of swelling seems to take precedence over glutathione-induced lysis, and the formation of lipid peroxide that is ordinarily induced by glutathione does not occur. This report deals wit,21 the detailed interrelationships of these phenomena. Such cffccts of phosphate and arsenate arc of interest. because several workers, including Calvin (8), Fluharty and Sanadi (9), and Sewton (lo), have suggested that disulfide cleavage might play a role in osidative phosphorylation. In the preceding palmer (a), we have pointed out that lipid pcrosides might arise from some intermediate of osidative phosphorylation under certain conditions. The terms “swelling-1ysis” or “lysis” are used here to describe the changes produced in liver mit,ochondria by GSSG + GSH in order to relate this work to literature on GSH-induced “swelling” of mitochondria. Actually, at least three different kinds of “swelling” occur with isolated liver mitochondria (2): (a) swelling, with very little loss of matrix protein, as seen with phosphate or thyroxine + substmte; (b) lysis, with loss of 50 to 60% of the protein in aolublc form but with retention of membrane structures which may be “ghosts,” a change seen with low Fe++ ion; and (c) disintegrntion, which is lysis with disintegration of the membrane into very small part.icles and soluble proteins. As indicated in the preceding paper (2), the action of GSSG + GSH probably involves all t,hree.