A low-calorie unrestricted protein diet attenuates kidney damage in uninephrectomized spontaneously hypertensive rats

Background/Aims: Uninephrectomized, spontaneously hypertensive rats (UNX-SH R) develop glomerular hyperfiltration, hyperfusion, and interstitial infilt rate of the remnant kidney. Consequently, UNX-SHR is a useful animal model to investigate mechanisms involved in the progression of hypertensive renal disease. Methods: Body weight; tail systolic blood pressure (SBP); urine e xcretion of protein, urea, and electrolytes; and serum biochemistry were de termined in UNX-SHR at 2 months of age prior to uninephrectomy (week 0), pr ior to treatment (week 8) with a low-calorie (LC) or control diet, and one month after diet treatment (week 12). The LC diet was modified to allow equ al intake of protein, sodium phosphorus, and other nutrients in both groups . Results: UNX-SHR treated with the LC diet had significantly lower body we ights and SEP at the end of the experiment than did the controls (p < 0.000 1). Changes in serum biochemistry and 24-hour urinary excretion of protein, sodium, potassium, and urea nitrogen in both groups were not statistically significant. The final glomerular filtration rate and renal plasma flow we re similar in both groups, but the LC diet significantly reduced the glomer ular damage index (0.0007), mesangial expansion index (p < 0.002), volume o f interstitium per cortex (p < 0.0003), tubular interstitium volume fractio n (p < 0.0008), glomerular volume (p < 0.02), and remnant kidney weight (p < 0.01). Conclusion: We demonstrated that in UNX-SHR, the prevention of ren al damage by LC diet may involve diminished glomerular growth and interstit ial infiltrate without changes in renal hemodynamics. Consequently, LC diet , regardless of protein ingestion, may be an important tool in the preventi on of renal damage in hypertension. Additional studies of obese-hypertensiv e rats may confirm the beneficial effect of a LC diet and weight reduction on the renal damage of obesity-hypertension.