This study shows that incubation of rat liver mitochondria in the presence of the thiol/amino reagent 4,4-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) is followed by inhibition of both succinate supported respiration and oxidative phosphorylation, Half-maximal inhibition of succinic dehydrogenase activity and succinate oxidation by mitochondria was attained at 55.3 and 60.8 mu M DIDS, respectively. DIDS did inhibit the net ATP synthesis and ATP double left right arrow [P-32]Pi exchange reaction catalyzed by submitochondrial particles in a dose-dependent manner (K-i = 31.7 mu M and K-i = 32.7 mu M), respectively. The hydrolytic activities of uncoupled heart submitochondrial particles and purified F-1-ATPase were also inhibited 50% by 31.9 and 20.9 mu M DIDS, respectively.5241984799806