Vajreswari Ayyalasomayajula, Rupalatha Maddala, Rao Pyata Srinivasa
National Institute of Nutrition, Indian Council of Medical Research, Jamai Osmania PO, Hyderbad-500007, A.P. India.
J Nutr Sci Vitaminol (Tokyo). 2002 Oct;48(5):365-70. doi: 10.3177/jnsv.48.365.
Three experimental diets with varied n-6-to-n-3 fatty acid ratios (120, 40 and 8) were prepared by a suitable blending of safflower oil containing 72.5% linoleic (18:2 n-6) acid and non-detectable levels of alpha-linolenic (18:3 n-3) acid, and soybean oil having 56.1% linoleic (18:2 n-6) acid and 7.9% alpha-linolenic (18:3 n-3) acid. These diets were fed to weanling female Wistar/NIN (inbred) rats for 16 wk to assess the impact of altered dietary n-6-to-n-3 fatty acid ratio on erythrocyte membrane (EMS) cholesterol, phospholipids, fatty acid composition and activities of membrane-bound enzymes such as Na+,K+-ATPase, Ca2+, Mg2+-ATPase and acetylcholinesterase. Activities of total and ouabain-sensitive-ATPases were significantly higher in the erythrocyte membranes of rats fed diets with a n-6-to-n-3 fatty acid ratio of 40 compared to other groups, whereas the erythrocyte membrane-bound acetylcholinesterase was significantly different among the three groups. The highest and lowest activities for this enzyme were observed in the dietary groups with n-6-to-n-3 fatty acid ratios of 8 and 40 respectively. However, the EMS of rats fed diets with a n-6-to-n-3 fatty acid ratio of 40 alone had significantly higher Ca2+,Mg2+-ATPase compared to those of other two groups. Significant increases were observed in absolute amounts of cholesterol, phospholipids and molar ratio of cholesterol to phospholipids in the EMS of rats fed a diet with a very high 18:2 n-6-to-18:3 n-3 fatty acid ratio (120) as compared to those from the dietary group with 18:2 n-6-to-18:3 n-3 fatty acid ratio (40), which had the lowest levels of cholesterol, phospholipids and cholesterol-to-phospholipid molar ratio. On the other hand, the EMS from rats fed a diet with a very low n-6-to-n-3 fatty acid ratio (8) had significantly lower cholesterol and higher proportions of stearic (18:0), oleic (18:1 n-9), eicosapentaenoic (20:5 n-3), and docosahexaenoic acids, and a higher ratio of docosahexaenoic (22:6 n-3) acid-to-a-linoleic (18:3 n-3) acid compared to the EMS from a very high n-6-to-n-3 fatty acid ratio of 120. Although these changes in EM fatty acid profiles were expected of the respective dietary regimens, the observed changes in the activities of membrane-bound enzymes could have resulted from their interaction with membrane cholesterol, phospholipids and fatty acyl chains.
通过将含有72.5%亚油酸（18:2 n-6）且α-亚麻酸（18:3 n-3）含量不可检测的红花油与含有56.1%亚油酸（18:2 n-6）和7.9%α-亚麻酸（18:3 n-3）的大豆油进行适当混合，制备了三种n-6与n-3脂肪酸比例不同（分别为120、40和8）的实验性日粮。将这些日粮喂给断乳雌性Wistar/NIN（近交系）大鼠16周，以评估日粮中n-6与n-3脂肪酸比例的改变对红细胞膜（EMS）胆固醇、磷脂、脂肪酸组成以及膜结合酶如Na⁺,K⁺-ATP酶、Ca²⁺,Mg²⁺-ATP酶和乙酰胆碱酯酶活性的影响。与其他组相比，饲喂n-6与n-3脂肪酸比例为40的日粮的大鼠红细胞膜中总ATP酶和哇巴因敏感ATP酶的活性显著更高，而红细胞膜结合的乙酰胆碱酯酶在三组之间有显著差异。该酶的最高和最低活性分别在n-6与n-3脂肪酸比例为8和40的日粮组中观察到。然而，仅饲喂n-6与n-3脂肪酸比例为40的日粮的大鼠的红细胞膜中Ca²⁺,Mg²⁺-ATP酶活性显著高于其他两组。与18:2 n-6与18:3 n-3脂肪酸比例为40（胆固醇、磷脂和胆固醇与磷脂摩尔比水平最低）的日粮组相比，饲喂18:2 n-6与18:3 n-3脂肪酸比例非常高（120）的日粮的大鼠红细胞膜中胆固醇、磷脂的绝对含量以及胆固醇与磷脂的摩尔比显著增加。另一方面，饲喂n-6与n-3脂肪酸比例非常低（8）的日粮的大鼠的红细胞膜胆固醇显著降低，并含有更高比例的硬脂酸（18:0）、油酸（18:1 n-9）、二十碳五烯酸（20:5 n-3）和二十二碳六烯酸，且二十二碳六烯酸（22:6 n-3）与α-亚麻酸（18:3 n-3）的比例高于18:2 n-6与18:3 n-3脂肪酸比例非常高（120）的日粮组。尽管预计红细胞膜脂肪酸谱的这些变化是由各自的日粮方案导致的，但观察到的膜结合酶活性变化可能是由于它们与膜胆固醇、磷脂和脂肪酰链的相互作用引起的。
