Long-term effect of partial nephrectomy on biological parameters, kidney histology, and guanidino compound levels in mice.

The long-term adverse consequences of early renal mass reduction in mice have not yet been investigated. The effects of partial surgical nephrectomy (NX) in 2-month-old mice on some biological parameters, on histopathologic and morphometric features of the kidney, and on urea and guanidino compound (GC) levels in plasma, urine, and brain were examined at 10 days, and 1, 2, 4, and 12 months postsurgery. Body weight, urinary volume, and plasma urea were most affected at 10 days and 12 months post-NX. NX-induced changes in the remaining renal tissue (including hypertrophy, glomerular mesangial expansion, and presence of protein casts) increased with age. As in human renal insufficiency, NX mice showed significantly higher plasma guanidinosuccinic acid (GSA) and creatinine (CTN) levels at all studied periods. The same tendency could be seen for most other plasma GCs examined, except for arginine (Arg), guanidinoacetic acid (GAA), and homoarginine (HA). As seen in human pathobiochemistry, the latter 2 compounds tended to be lower in NX mice in our follow-up study. Remarkably, and also similar to humans, NX mice excreted less GAA and more GSA than controls during the entire follow-up study. During the follow-up, excretion levels of GAA were unchanged in NX and sham-operated mice. In brain, GAA and gamma-guanidinobutyric acid (GBA) levels were always higher in NX mice with a tendency to respectively increase or decrease over time in NX as well as sham-operated mice. Although urea and GC metabolism were influenced by time post-NX and aging, the model was confirmed to display a mild stable chronic impairment of renal function. Histopathologic and morphometric changes of the kidney increased with age.