Mitochondrial Swelling and Uncoupling Activity of Long-Chain Fatty Acids

The effect of various fatty acids on the swelling-contraction and oxidative phosphorylation of mitochondria from rat liver and Ehrlich ascites tumor cell have been studied and the results are as follows: 1. The swelling of rat liver mitochondria is induced by fatty acid. The extent of this uncoupling action is in the descending order of myristate, laurate, parlmitate, stearate and behenate in saturated fatty acid and linoleate, linoleneate, richinoleate and oleate in the unsaturated fatty acid. This swelling action is stronger with unsaturated fatty acids than that of saturated ones and cis form is stronger than trans form. 2. The uncoupling oxidative phosphorylation of rat liver mitochondria is also observed with these fatty acids and the activities are proportional to the degree of the swelling action. 3. The degree of swelling of rat liver mitochondria is proportional to the concentration of oleate and is inhibited by anaerobiosis and respiratory inhibitor except amytal. 4. The mitochondria swollen by fatty acid can be recontracted reversibly by ATP, Mg++ and bovine serum albumin. 5. The swelling action of sodium oleate is the strongest on mitochondria from rat liver, followed by those from the liver of Ehrlich ascites tumor bearing mouse, Ehrlich ascites tumor cells and solid Ehrlich tumor cells. 6. Sodium oleate inhibits the incorporation of 32p into ATP, ADP, GTP and UDPG in mitochondria.