Changes in muscle mitochondrial lipid composition resulting from training and exhaustive exercise

Abstract

This study was undertaken to determine if the changes in mitochondrial structure and function that occur in muscle with exhaustive exercise could be caused by alterations in lipid composition of mitochondrial membranes. Further, the effect of training on lipid composition was studied to ascertain if lipid changes accompany the adaptation in the level of mitochondrial protein. Training decreased free fatty acids and triglycerides. Exhaustion of untrained animals resulted in increases of total phospholipid and phosphatidyl choline while exhaustion of trained rats caused a lowering of total phospholipid and phosphatidyl choline. Alterations in membrane lipid composition are most likely not the cause of changes in mitochondrial structure and function after exhaustive exercise since mitochondrial yield and lipid levels did not change in concert; i.e. muscle mitochondrial yield was decreased in both untrained and trained rats while total phospholipids were increased in untrained rats and decreased in trained rats as a result of exhaustive exercise. Although the physiological significance of the effects observed remains to be determined, this study does demonstrate that the lipid composition of mitochondria is not a constant parameter but can change in response to a chronic (training) or acute (exhaustive exercise) physiological condition.