Membrane phospholipid and fatty acid changes in the mitochondrial and sarcolemmal fractions of the heart in adjuvant arthritic rats.

Adjuvant arthritis was found to induce changes in phospholipid and fatty acid composition as well as in membrane fluidity of mitochondrial and sarcolemmal fractions in the rat heart. In the sarcolemmal fraction, phosphatidylcholine content was decreased, while phosphatidylserine, phosphatidylinositol and the lysocompounds of phospholipids were increased. Mitochondria isolated from the heart of rats with adjuvant disease contained less linoleic acid than control samples. Docosatetraenoic acid and docosahexaenoic acid levels were shown to be increased in both mitochondrial and sarcolemmal fractions of the heart in treated animals. Electron spin resonance studies indicated that the break points of the curves obtained by plotting the order parameters against temperature changes were slightly shifted to lower temperature region in both subcellular fractions of arthritic rat hearts. As compared to the control values, membrane fluidity was increased both in mitochondrial and sarcolemmal fractions. The relationship of these alterations to our previous findings that adjuvant arthritis protected the rats against fatal post-infarctions arrhythmias needs further elucidation.