Effects of repetitive diet-induced fluctuations in plasma phosphorus on vascular calcification and inflammation in rats with early-stage chronic kidney disease

Cardiovascular disease is a major cause of death among hemodialysis patients. Hyperphosphatemia induces cardiovascular disease through vascular endothelial dysfunction and calcification. Repetition of a short-term excessive-phosphorus (P) diet causes transient elevations in plasma P and subsequent vascular endothelial dysfunction in normal rats. The purpose of this study was to investigate the effects of the P fluctuation on vascular calcification and inflammation in rats after unilateral nephrectomy as an early-stage chronic kidney disease (CKD) model. Rats were bred for 36 days; CP group, fed a control P (0.6%) diet; HP group, fed a high-P (1.2%) diet; and P fluctuation group, fed low-P (0.02%) and high-P diets alternately every 2 days. Influences on vascular calcification were analyzed using Von Kossa staining and measurement of vessel Ca content. The influence on inflammation was measured as urinary levels of 8-hydroxy-2'-deoxyguanosine. We demonstrated that the P fluctuation group showed similar vascular calcification and inflammation to the HP group, despite having the same total P intake as the CP group. A diet avoiding P fluctuations may be important for patients with early-stage CKD.