Renoprotective and antihypertensive effect of combination therapy with a low protein diet, long-term exercise and angiotensin II receptor antagonist in rats with renal ablation

A low-protein diet (LPD) has been prescribed to alleviate uremic symptoms, and to delay the aggravation of chronic renal failure (CRF). However, it has been suggested that LPD treatment causes malnutrition and attenuation of muscle power. On the other hand, it also has been suggested that appropriate long-term exercise training (EX) may lead to improvement of the physical fitness and quality of life (QOL) in patients with CRF. However, there is no definitive conclusion as to whether EX has any renal protective effect or not. We assessed the effects of combination therapy with LPD and EX. We also assessed the effects of a combination of these therapies and the angiotensin II receptor antagonist, olmesartan (OLS). Male Wistar-Kyoto rats that were five-sixth-nephrectomized were divided into 6 groups; 1) normal-protein diet (NPD); 2) NPD and EX with treadmill running (1 h/day, 5 days/week for 12 weeks) (NPD+EX); 3) LPD; 4) LPD+EX; 5) LPD+EX with OLS (10 mg/kg/day for 12 weeks) (LPD+EX+OLS); and 6) Sham-operated (S). Systolic blood pressure (SBP) in the NPD+EX, LPD+EX, LPD+EX+OLS, and S groups was significantly lower than in the NPD group. Moreover, SBP in the LPD+EX+OLS was significantly lower than in all the other groups. LPD, LPD+EX, and LPD+EX+OLS induced a significant decrease in UP, Scr and BUN compared with the NPD group. UP in the LPD+EX, LPD+EX+OLS, and S groups was significantly lower than in the LPD group. The index of glomerular sclerosis (IGS) and relative interstitial volume (RIV) in the NPD+EX, LPD, LPD+EX, LPD+EX+OLS, and S groups were significantly lower than the values in the NPD group. IGS and RIV in the LPD, LPD+EX, LPD+EX+OLS, and S groups were significantly lower than the values in the NPD+EX and LPD groups. Glomerular ED-1 positive cells in the LPD+EX, LPD+EX+OLS, and S groups was significantly fewer than in the NPD groups. These results indicate that LPD and EX have renoprotective effects, and suggest that the combination therapy with LPD and EX provides greater renoprotective effects than LPD alone. Moreover simultaneous treatment of OLS and LPD+EX provides greater antihypertensive and antiproteinuric effects than treatment with LPD+EX.