Eiam-Ong S, Eiam-Ong S, Sabatini S
Department of Physiology, Chulalongkorn University, Bangkok, Thailand.
J Med Assoc Thai. 2001 Jun;84 Suppl 1:S295-305.
Renal cortical brush-border (BBM), basolateral membrane (BLM), and medullary plasma membrane (mPM) preparations were analyzed to assess the effects of life-long food restriction in aged rats on membrane lipid content. Young male Fischer 344 x Brown-Norway F1 rats consumed food ad libitum (young AL) or were food-restricted (FR, 60% of AL consumption) for either 6 weeks (young FR) or until the age of 30 months old (old FR). Senescent FR rats had 50 per cent decreases in fractional excretion of Na and K (p < 0.001) as compared with the young AL rats. Long-term FR reduced phosphate and titratable acid excretion by 80 per cent (p < 0.001). These values were not significantly different from those observed in young rats during 6 weeks of FR. Food restriction decreased renal Na, K-ATPase activity by 50 per cent (p < 0.001) in both old and young FR animals. Reduction of food intake, in old and young rats, decreased all BBM phospholipid concentrations (phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin) by 50 per cent than in the AL rats (p < 0.001). In BLM, chronic FR resulted only in lower phosphatidylcholine concentration (by 21%, p < 0.05) while phosphatidylethanolamine was increased approximately 80 per cent (p < 0.001). Total phospholipid content in mPM was progressively decreased by 23 per cent (p < 0.05) in the young FR group to be 55 per cent (p < 0.001) in the old FR rats. Cholesterol content was reduced in BBM and mPM by 38 per cent and 25 per cent (p < 0.05), respectively, during long-term FR. Both total phospholipid and cholesterol contents detected in mPM of the old FR rats were significantly lower than those obtained from the young FR animals (by 42%, p < 0.001 and 12%, p < 0.05, respectively). Plasma glucose, blood urea nitrogen, and body weight maintained at significantly lower levels during chronic FR. That life-long FR could prevent renal membrane lipid deposition and could lower renal work may explain the mechanisms that FR can delay the onset and diminish the severity of age-associated renal diseases.
分析了肾皮质刷状缘（BBM）、基底外侧膜（BLM）和髓质质膜（mPM）制剂，以评估老年大鼠终身食物限制对膜脂质含量的影响。年轻雄性Fischer 344×Brown-Norway F1大鼠随意进食（年轻AL组）或进行食物限制（FR组，进食量为AL组的60%），持续6周（年轻FR组）或直至30月龄（老年FR组）。与年轻AL组大鼠相比，衰老的FR组大鼠钠和钾的分数排泄减少了50%（p<0.001）。长期FR使磷酸盐和可滴定酸排泄减少了80%（p<0.001）。这些值与年轻大鼠在FR 6周期间观察到的值无显著差异。食物限制使老年和年轻FR组动物的肾钠钾ATP酶活性降低了50%（p<0.001）。老年和年轻大鼠食物摄入量的减少使所有BBM磷脂浓度（磷脂酰丝氨酸、磷脂酰胆碱、磷脂酰乙醇胺和鞘磷脂）比AL组大鼠降低了50%（p<0.001）。在BLM中，慢性FR仅导致磷脂酰胆碱浓度降低（降低21%，p<0.05），而磷脂酰乙醇胺增加了约80%（p<0.001）。年轻FR组mPM中的总磷脂含量逐渐降低23%（p<0.05），老年FR组大鼠降低至55%（p<0.001）。长期FR期间，BBM和mPM中的胆固醇含量分别降低了38%和25%（p<0.05）。老年FR组大鼠mPM中检测到的总磷脂和胆固醇含量均显著低于年轻FR组动物（分别降低42%，p<0.001和12%，p<0.05）。慢性FR期间，血浆葡萄糖、血尿素氮和体重维持在显著较低水平。终身FR可预防肾膜脂质沉积并降低肾脏工作负荷，这可能解释了FR可延缓与年龄相关的肾脏疾病的发生并减轻其严重程度的机制。
