Mandon E C, de Gómez Dumm I N, Brenner R R
Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CONICET UNLP, Facultad de Ciencias Médicas, La Plata, Argentina.
Acta Physiol Pharmacol Latinoam. 1988;38(1):49-58.
High carbohydrate and high protein diets administered to rats for only three days decreased and increased, respectively, the arachidonate/linoleate ratio (20:4 n6/18:2 n6) in total lipids of lung, kidney, and liver microsomes. In liver and kidney this correlated with a significant decrease in the first dietary condition, and with an increase in the second, of delta 6 desaturase activity, measured by the rate of conversion of 1-14C linoleate n6 to 1-14C linolenate n6. Such an enzymatic activity was not detectable in lung microsomes, probably because of the low capacity of this tissue to produce the coenzyme A ester of the substrate used, since in lung the effects of dietary manipulation on the 20:4/18:2 ratios were as large as in liver. Significant differences were observed in microsomes of the three tissues examined in the steady state fluorescence anisotropy (rs) of diphenylhexatriene, which correlated with their cholesterol/phospholipid ratios. Both were lower in microsomes from liver than from the other two tissues, and both remained unchanged in each tissue under the dietary regimens studied. The results indicate that the observed effects of high carbohydrate and high protein diets on fatty acid delta 6 desaturation activity do not lead to apparent alterations in the physical properties of microsomal membranes.
仅对大鼠喂食三天的高碳水化合物和高蛋白饮食，分别降低和升高了肺、肾和肝微粒体总脂质中的花生四烯酸/亚油酸比率（20:4 n6/18:2 n6）。在肝脏和肾脏中，这与第一种饮食条件下δ6去饱和酶活性的显著降低以及第二种饮食条件下该活性的升高相关，δ6去饱和酶活性通过1-14C亚油酸n6转化为1-14C亚麻酸n6的速率来测定。在肺微粒体中未检测到这种酶活性，可能是因为该组织产生所用底物辅酶A酯的能力较低，因为在肺中饮食调控对20:4/18:2比率的影响与在肝脏中一样大。在所检查的三种组织的微粒体中，观察到二苯基己三烯的稳态荧光各向异性（rs）存在显著差异，这与它们的胆固醇/磷脂比率相关。肝脏微粒体中的两者均低于其他两个组织，并且在研究的饮食方案下，每个组织中的两者均保持不变。结果表明，观察到的高碳水化合物和高蛋白饮食对脂肪酸δ6去饱和活性的影响不会导致微粒体膜物理性质的明显改变。
