An improved postconditioning algorithm: gradually increased reperfusion provides improved cardioprotection in rats.

: The aim of the present study was to investigate whether a gradually increasing reperfusion algorithm, in which the brief reperfusion was lengthened as the duration of each reperfusion/reocclusion cycle remained fixed, enhances cardioprotection. Rats were randomized into 5 groups: the sham, reperfusion injury (R/I), gradually decreased reperfusion (GDR; 30/10‑25/15‑15/25‑10/30 sec of reperfusion/reocclusion), equal reperfusion (ER; 4 20/20‑sec reperfusion/reocclusion cycles) and gradually increased reperfusion (GIR; 10/30‑15/25‑25/15‑30/10 sec of reperfusion/reocclusion). The rats were sacrificed to measure serum markers, apoptotic indices and infarct size. Western blot analyses were used to analyze the expression of molecules involved in important signaling pathways. All the three postconditioning patterns were found to provide cardioprotection (P 0.05). All the variables measured in the present study were significantly improved in the GIR group compared with the GDR group (P<0.05). In conclusion, the association between brief reperfusion and reocclusion is an important factor in postconditioning algorithms. Additionally, GIR results in improved cardioprotection compared with that achieved by the remaining algorithms examined.