Compared with the control group , the serum HO-1 was significantly increased at 6 , 12 , 24 , 48 h after the heart valve replacement surgery in both the RIPerC and RIPostC groups ( P < 0.05 ) ; the SCr , BUN , urinary NGAL and serum iron values were decreased at 6 , 12 , 24 , 48 h after the heart valve replacement surgery in both the RIPerC and RIPostC groups ( P > 0.05 ) .