Effects of trialkyllead compounds on mitochondrial energy conservation

The effects of triethyllead acetate and tri-n-butyllead acetate on rat liver mitochondrial ATPase, succinate-driven ATP synthase and mitochondrial membrane potential have been compared with those of the equivalent organotin compounds. ATP synthase I₅₀ values were approximately four times the ATPase I₅₀ values for organotin compounds but the reverse pattern of activity is observed with trialkyllead compounds, which are 5-10 times more effective inhibitors of ATP synthase than of ATPase activity. The primary effects of trialkyltins are as inhibitors of the ATPase complex with relatively minor effects on mitochondrial membrane potential ($PS). In contrast, trialkylleads are potent uncoupling agents, which accounts for their potent inhibition of ATP synthesis. The uncoupling action of trialkylleads and trialkyltins is independent of chloride concentration and is unlikely to be due to Cl^?/OH^? exchange.