Lipid peroxidation in Ehrlich ascites cell mitochondria is not determined by the polyunsaturated fatty acid content of the membrane

Lipid peroxidation intensity is compared in Ehrlich Ascites Cell and in liver mitochondria, prepared from tumor bearing mice. Malondialdehyde formation is negligible in intact ascites tumour mitochondria, but it is significantly increased in permeabilised mitochondria and in isolated mitochondrial membranes. We suggest that the resistance against oxidative stress is a consequence of efficient protective mechanisms operating in the intact tumour mitochondria and the low level of polyunsaturated fatty acids under these circumstances cannot be the rate limiting factor in lipid peroxidation. Succinate, an effective inhibitor of mitochondrial lipid peroxidation in liver, cannot determine malondialdehyde formation in ascites tumour mitochondria.