Antialbuminuric actions of calcilytics in the remnant kidney

Hyperphosphatemia accelerates the progression of chronic kidney diseases. In the present study, the effects of ronacaleret, a calcilytic agent, on renal injury were assessed in the following four groups of rats: 5/6-nephrectomized Wistar rats as a control (C group), rats treated with ronacaleret (3 mg·kg^-1·day^-1; R group), rats treated with calcitriol (30 ng·kg^-1·day^-1; V group), and rats treated with both ronacaleret and calcitriol (R + V group). Three months later, rats were euthanized under anesthesia, and the remnant kidneys were harvested for analysis. Albuminuria was lower in the R and V groups than in the C group (P < 0.05). Creatinine clearance was elevated in the R and V groups compared with the C group (P < 0.05). Serum Ca²⁺ and renal ANG II were higher in the R + V group than in the C group (P < 0.05 for each), and serum phosphate was reduced in the R group compared with the C group (P < 0.05). Fibroblast growth factor-23 was lower in the R group and higher in the V and R + V groups than in the C group. However, parathyroid hormone did not differ significantly among the four groups. Renal klotho expression was elevated in the R and V groups compared with the C group (P < 0.05). The present data indicate that ronacaleret preserves klotho expression and renal function with reductions in serum phosphate and albuminuria in 5/6-nephrectomized rats. Our findings demonstrate that vitamin D prevents declines in klotho expression and renal function, suppressing albuminuria.