Table 1.
The impact of age on renal structural and functional indices in male Fischer 344 rats
| Age, months | ||||||
|---|---|---|---|---|---|---|
| 4 | 8 | 12 | 18 | 24 | 24-CR | |
| Body weight, g | 345 ± 7 | 379 ± 16 | 409 ± 7 | 427 ± 14 | 421 ± 9 | 315 ± 6 |
| BUN, mg/dl | 26.6 ± 2.3 | 21.8 ± 2.3 | 22.7 ± 3.5 | 28.9 ± 4.4 | 50.0 ± 3.8 | 31.3 ± 4.5 |
| Creatinine clearance, ml/min/g kidney | 2.61 ± 0.05 | 2.29 ± 0.41 | 2.68 ± 0.73 | 2.48 ± 0.84 | 0.970 ± 0.228 | 1.98 ± 0.34 |
| GS | 0.00 ± 0.00 | 0.50 ± 0.29 | 1.00 ± 0.00 | 1.25 ± 0.25 | 3.5 ± 0.29 | 0.5 ± 0.29 |
| Kidney weight, g | 2.29 ± 0.05 | 2.42 ± 0.19 | 2.58 ± 0.08 | 2.84 ± 0.05 | 3.43 ± 0.31 | 2.24 ± 0.08 |
| Kidney/body weight, ×103 | 6.63 ± 0.06 | 6.35 ± 0.29 | 6.31 ± 0.16 | 6.70 ± 0.35 | 8.16 ± 0.80 | 7.09 ± 0.19 |
| Kim-1, pg/ml | 124 ± 3 | 114 ± 2 | 146 ± 19 | 234 ± 27 | 962 ± 632 | 147 ± 33 |
| Kim-1/creatinine, μg/g | 5.33 ± 0.54 | 5.33 ± 0.40 | 5.49 ± 0.87 | 12.5 ± 1.7 | 173 ± 239 | 27.6 ± 5.3 |
| Serum creatinine, mg/dl | 0.693 ± 0.021 | 0.847 ± 0.123 | 0.829 ± 0.258 | 0.934 ± 0.286 | 2.23 ± 0.61 | 0.987 ± 0.175 |
| Total protein, mg/dl | 2.00 ± 0.12 | 1.65 ± 0.09 | 2.42 ± 0.35 | 2.24 ± 0.29 | 5.94 ± 1.18 | 0.938 ± 0.262 |
| Tubular damage | 0.50 ± 0.29 | 1.25 ± 0.25 | 1.00 ± 0.00 | 1.25 ± 0.25 | 3.25 ± 0.48 | 0.25 ± 0.25 |
| Urine albumin, mg/dl | 7.36 ± 0.16 | 5.97 ± 0.22 | 21.5 ± 3.5 | 16.6 ± 3.6 | 125 ± 29 | 9.18 ± 1.42 |
| Albumin/creatinine, g/g | 3.17 ± 0.30 | 2.80 ± 0.18 | 8.08 ± 1.28 | 8.87 ± 2.00 | 225 ± 132 | 17.3 ± 2.4 |
| Urine creatinine, μmol/kg/days | 6.00 ± 0.40 | 5.55 ± 0.34 | 5.96 ± 0.17 | 5.26 ± 0.41 | 3.31 ± 0.55 | 2.99 ± 0.37 |
| Urine volume, ml/day | 10.1 ± 1.0 | 11.3 ± 1.3 | 10.4 ± 0.2 | 13.5 ± 0.9 | 28.8 ± 6.2 | 19.6 ± 1.2 |
Male Fisher 344 rats were fed an AL diet or a CR diet. Time course study was performed to assess functional and structural damage. Rats fed the AL diet were evaluated at 4, 8, 12, 18, and 24 months (4-, 8-, 12-, 18-, and 24-AL); rats fed the CR diet were evaluated at 24 months (24-CR). Each value represents the mean ± SE from 4 animals. To more accurately represent the center and spread of values for Kim-1, Kim-1/creatinine, urine albumin and albumin/creatinine, means were calculated from the log10 transforms; the antilog of the mean is shown in the table. Standard errors for these variables were approximated as the antilog of the margin of error for 95% confidence intervals around the log-transformed means. Functional parameters of the kidney were measured, including blood urea nitrogen (BUN), serum creatinine, urinary albumin, and creatinine clearance. The 24-AL group had the greatest impairment of function, which was corrected in the 24-CR group. Structural damage was assessed by blind histological evaluation, in which a score between 0 and 4 was given for glomerulosclerosis (GS) and tubular damage (0 = normal and 4 = extensive damage). GS and tubular damage were high in the 24-AL group, but were back to baseline in the 24-CR group.