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(199) Test battery for distinguishing various mechanisms of toxicity on energy production. Escher, Beate 1, Hunziker, René1, Schwarzenbach, René 1, 1 ABSTRACT- The production of energy, i.e., the conversion of light or other forms of energy into ATP, is a vital process in any cell. There are various ways in which environmental pollutants interfere with energy transduction in mitochondria and chloroplasts. Among them are uncoupling of the electrochemical proton gradient, inhibition of the electron transport chain, or inhibition of the ATP synthesis. For these modes of toxic action there are several tests systems already available. However, it is often difficult to compare the results due to differences in test organisms, cells, or cell fragments used. This problem is of particular importance for pollutants, which act according to several mechanisms concomitantly. We propose a novel test system consisting of a modularly built spectrophotometer/luminometer that allows one to quantitatively distinguish the mechanisms described above. Chromatophores of Rhodobacter sphaeroides are used as model systems for energy-transducing membranes. The test system was applied to investigate the acute toxicity of triorganotin compounds. Besides exhibiting the well-known hydroxide/chloride shuttle, triorganotins may also act as inhibitors of the cytochrome b complexes of the electron transfer chain and of the ATP synthase, and are suspected to act as protonophoric uncouplers. Application of the novel test system revealed inhibitory activity on the electron transfer chain only at high concentrations but protonophoric uncoupling and inhibition of the ATP synthesis occurred at comparable concentration ranges. Key words: uncoupling, inhibition, ATP synthesis, triorganotin |
