Remote Ischemic Conditioning in a Model of Severe Renal Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) injury is a leading cause of acute renal dysfunction. Remote ischemic conditioning (rIC) is known to protect organs exposed to I/R. We sought to investigate whether rIC would influence renal function recovery in a severe renal I/R injury rat model. Rats were randomly assigned to four experimental groups following median laparotomy and right nephrectomy: Sham (n = 6); 30-min left renal ischemia (RI) only (n = 20); RI + rIC (n = 20) (four 5-min cycles of limb ischemia interspersed with 5-min limb reperfusion during RI); and RI + erythropoietin pretreatment (EPO) (n = 20). Renal function was evaluated by assessing blood urea nitrogen (BUN) and serum creatinine (Cr) levels before surgery and after 1 day of reperfusion. All animals were monitored for 7 days for survival analysis. BUN and Cr baseline levels did not significantly differ between groups. At day 1, BUN and Cr were significantly higher than baseline values in all groups. BUN and Cr levels did not significantly differ at day 1 between RI and RI + rIC (P = 0.68). Conversely, EPO pretreatment injected 60 min before RI was associated with lower BUN and Cr levels compared with RI (P < 0.001 and P = 0.003, respectively) and RI + rIC (P < 0.001 and P = 0.001, respectively). In addition, 7-day survival rates were significantly higher in the Sham group (100%) compared with RI (50%; P = 0.039 vs. Sham) and RI + rIC (45%; P = 0.026 vs. Sham). Conversely, survival rate did not significantly differ between the Sham and RI + EPO groups (70%, P = 0.15). In conclusion, rIC affected neither acute renal dysfunction nor early mortality in a severe I/R renal injury rat model, contrary to EPO pretreatment.