The present study was designed to examine the effects of EFA deficiency (EFAD) on biochemical, functional, and structural
aspects of the kidney in growing and adult rats fed a normal or EFAD diet for 9 wk after weaning. Food and fluid intake (FI),
urine volume, and Na
+ and K
+ excretions were measured weekly from weeks 4 to 8 by placing the rats in individual metabolic cages for 24 h. At week 9,
Li
+ and a 5% water load, respectively, were administered at 14 and 1.5 h prior to glomerular and proximal tubular function studies,
as assessed by 3-h creatinine (C
Cr) and Li
+ (C
Li+) clearances. Hematocrit and urine volume; serum and urine [Cr], [Li
+], [Na
+], and [K
+]; and renal FA distribution were also measured. Data [corrected to 100 g/body weight (bw) and presented as means ±SEM] were
significant, at
P<-0.05. Despite a similar ingestion of solids from weeks 4 to 7 (weeks 7 to 10 of life), the rats on the EFAD diet showed
a decreased body weight from week 5. From weeks 4 to 8, Fl and urine volume were similar for both groups, but the Fl increased
at week 6 in the EFAD group; 24-h Na
+ and K
+ excretions were similar at all weeks, except for an increase in the EFAD group for both ions at week 7. In the EFAD group,
C
Cr and C
Li+ decreased by 27 and 56.3%, respectively (385.7±33.4 vs. 280±21.1, and 21.0±2.1 vs. 9.2±1.1 μL/min/100 g;
n=9 vs. 10), the latter result suggesting increased proximal reabsorption. The 3-h Na
+ and K
+ excretions were similar, but the Li
+ decreased (0.78±0.06×10
−2 vs. 0.32±0.03×10
−2 μeq/min/100 g) in the EFAD group, giving additional support to the suggestion. Renal structure was normal and similar for
both groups, but the EFAD group showed a more prominent proximal tubule brush border, together with heavier periodic acid-Schiff
staining in all specimens from weeks 5 to 9. In the EFAD group, FA of the n−9 and n−7 series were higher, but most of the
n−6 series were lower as a percentage of total lipids in the medulla and cortex. Medullary levels of 20∶4n−6 were maintained,
22∶4n−6 declined twice, arachidonic acid was maintained, and 20∶5n−3 was lower. The EFAD diet affected glomerular function,
proximal tubular structure and function, and FA distribution in the rat kidney.
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