Electrical potential dissipation induced by free fatty acids in pea stem mitochondria

Llnolcnic, linoleic, oleic, palmitic und stearic acids (FFA) collapse the electric4 polential of pea sicm mitochondria in the absence or in the presence of 0.5 mM M$\u201c. Higher concentrations of this cation (5 mM) lower the rate oi dissipation caused by linoleic, oleic and palmitic acids, while abolishing that induced by stearic acid. Cnrboxyatractyloside and ADP do no1 reverse the FFA-induced collapse both in the presence or absence of Meg2+, EDTA, EGTA or BHT do not influence the dissipation caused by FFA that, in addition, is not linked to lipid peroxidation evaluated as malondialdehyde or conjugated diene formation. Only linolenic acid sustains a peroxidation which. however. appears to be caused by its own oxidation catalysed by lipoxygenases rather lhan by membrane lipoperoxidation induced by this free fatty acid. These results suggest that neither the ATP/ADP exchanger nor lipid peroxidation appear to be involved in FFA-induced uncoupling in pea stem mitochondria