Gastrocnemius Muscle Lipids in Relation to Diet in Two Mouse Mutants, 129Re-dy and A2G-adr, with Abnormal Muscle Function

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Abstract
The lipids of gastrocnemius muscle from normal and dystrophic (dy) mice of the Bar Harbor, 129Re strain were studied. Animals were fed diets containing either 3.1% or 1.1% of total calories as linoleic acid. Lipid analyses were also done on muscle from a new mouse mutant, A2G-adr, which has abnormal muscle function, characterized by an arrested development of the righting response. These animals were fed the high linoleic acid diet only. Total lipid, triacylglycerol and cholesterol were elevated in the 129Re-dy irrespective of the diet; A2G-adr possessed significantly higher levels of cholesterol. Total phosphorus (.mu.g P/g muscle) and cholesterol/phospholipid ratios were elevated in the dy strains only. Cardiolipin was raised in the dy (low linoleic diet) and adr muscle; phosphatidylcholine was lower in the adr strain only. Linoleic acid esterified to phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine was elevated; arachidonic acid in phosphatidylserine was decreased in both mutants. Docosahexanoic acid (22:6) in all 3 dy phospholipids was decreased, independent of dietary treatment. The adr strain possessed normal levels of this fatty acid. The results specifically point to an abnormality in long-chain polyunsaturated fatty acid metabolism in gastrocnemius muscle in the 129Re-dy mutant; in the adr mutant they could reflect an abnormal increase in the number of muscle mitochondria.