INFLUENCE OF DIETARY PROTEIN CALORIE INTAKE ON RENAL MORPHOLOGY AND FUNCTION IN CATS WITH 5/6-NEPHRECTOMY/

BACKGROUND: Although still controversial, several studies in humans ha ve suggested That dietary protein restriction may slow the rate of pro gression of chronic renal failure. Thus, the influence of dietary prot ein on renal function and progression of renal failure has been the su bject of numerous studies in several animal models of chronic renal fa ilure, including rodents, dogs, and baboons. Because of the high incid ence of chronic renal failure in aged cats, and the high dietary prote in requirements of cats, we studied the effects of dietary protein int ake on renal function, proteinuria, and renal morphology in cats with reduced renal mass. EXPERIMENTAL DESIGN: Partial (5/6) nephrectomy was performed in 14 young adult female cats. Sham surgical procedures wer e performed in eight control cats. Control cats and cats with 5/6 neph rectomy were randomly assigned to diets containing either 27.6% (low) or 51.7% (high) protein and studied for 1 year. RESULTS: Renal mass re duction by 5/6 decreased glomerular filtration rate by 2/3 and signifi cantly increased proteinuria. Cats with remnant kidneys had significan tly higher systolic and mean blood pressures than control cats. Increa sed dietary protein/calorie intake significantly increased glomerular filtration rate and proteinuria in all cats. Glomerular filtration rat es remained stable in all cats over the year of study. However, high p rotein/calorie intake resulted in significant renal morphologic injury in remnant kidney cats that was prevented by dietary protein/calorie restriction. Light and electron microscopic glomerular changes in remn ant kidney cats fed the high protein diet were similar to changes prev iously reported in rats and dogs with remnant kidneys. CONCLUSIONS: Di etary protein/calorie restriction limits proteinuria and glomerular in jury in cats with remnant kidneys in a fashion similar to that reporte d in rats. However, the remnant kidney model in the cat appeared to be associated with a slower rate of progression compared with rats.