DIETARY-PROTEIN AND THE RENIN-ANGIOTENSIN SYSTEM IN CHRONIC RENAL-ALLOGRAFT REJECTION

We examined the effects of dietary protein restriction in fourteen pat ients with chronic kidney rejection. The patients were randomly assign ed, using a crossover design to two Ii-day periods, one on a low-prote in diet (0.55 g/kg/day) and the other on a high-protein diet (2 g/kg/d ay). The low protein diet was associated with a significant improvemen t in glomerular permselectivity without any change in blood pressure, glomerular filtration rate, or renal plasma flow. The low protein diet was also associated with a significant reduction in plasma renin acti vity. Acute converting enzyme inhibition decreased proteinuria when ad ministered at the end of the high protein diet, but had no additional antiproteinuric effect when given at the end of the low protein diet. Comparable reductions in blood pressure with hydralazine had no effect on proteinuria. Protein restriction was also associated with modest b ut significant fall in serum proteins. In conclusion, dietary protein restriction may improve the course of renal failure in chronic rejecti on partly by suppressing the renin-angiotensin system. Studies are nee ded to establish the safe level of dietary protein restricton in these patients and to assess the efficacy of such restriction in slowing th e progression of renal failure.