Lipid Content and Phospholipid Metabolism of Subcellular Fractions from Testes of Control and Retinol-deficient Rats

Lipid composition and phospholipid metabolism were studied in the subcellular fractions of normal and retinol-deficient rat testes. The total lipid from normal subcellular particles was highest in mitochondria (138 ± 4.4 mg/100 mg protein) and lowest in microsomes (70 ± 2.5 mg/100 mg protein). Approximately 60% of mitochondrial and microsomal lipid was phospholipid. In all subcellular fractions total cholesterol constituted about 12% of total lipid. Retinol deficiency produced in mitochondria and microsomes an increased lipid associated with protein. This increase was primarily phospholipid and cholesterol. Phosphatidylcholine was the major phospholipid of all fractions. Control phospholipid fatty acid patterns were similar for microsomes and soluble fractions. Deficiency caused a decreased percentage of docosapentaenoate in both of these fractions, while microsomes also exhibited an increased percentage of stearate and oleate and soluble fraction an increased percentage of linoleate and arachidonate. The peak incorporation of 24C-choline into phospholipids was about 12 hours for all subcellular fractions. Deficient rats had about 2.5 times greater incorporation. Half-lives of control subcellular phospholipids were approximately 300 hours for mitochondrial and soluble fractions and 100 hours for microsomes. Retinol deficiency reduced the half-lives of the two former fractions to about 160 hours, but did not affect the half-life of microsomal phospholipids.