Preparation of 5/6-nephrectomized rats and the effect of ZnSO4 injection on their red blood cell (RBC) levels. (A) Normal rats underwent a sham-operation or surgical removal of 5/6 of the kidney. After 25 days, rat blood was drawn, and RBC levels and other hematological indices of the rats were measured. (B) Effect of ZnSO4 injection on the RBC level of 5/6-nephrectomized rats. The 5/6-nephrectomized rats (25 days post surgery) were injected with either saline or 2.8 mg Zn/kg body weight of ZnSO4 solution. One, 2, or 4 days after injection, RBC levels and other hematological indices were measured. ** Significant difference between ZnSO4-injected and saline-injected rats (p < 0.01, n = 6). This figure is representative of three independent experiments.