[Protective effects of preconditioning phlebotomy against myocardial ischemia-reperfusion injury in rat].

Objective: To investigate the protective effect of preconditioning phlebotomy against ischemia-reperfusion injury and the role of calcitonin gene-related peptide (CGRP) in this protection mechanism.

Methods: Sixty SD rats were randomly assigned in equal number into control, phlebotomy, and CGRP polyclonal antibody (PcAb) groups, all of which were subjected to 30 min regional ischemic followed by two-hour reperfusion, initiated 15 min after phlebotomy in the latter 2 groups. The rats in CGRP PcAb group were given the antibody (2.5 mg/kg) before phlebotomy. After the operations, plasma CGRP level was determined in 8 rats from each group by radioimmunoassay, and the infarct size (IS) by nitro blue tetrazolium, represented as percentage of the area at risk (AAR).

Results: The mean plasma CGRP level was significantly increased in phlebotomy group compared with the levels in control and PcAb groups (F=12.4, P=0.032-0.005), and a significant reduction in IS (F=52.4, P<0.001) and IS/AAR (F=43.7, P<0.001) occurred in phlebotomy group.

Conclusion: Preconditioning phlebotomy has obvious cardioprotective effect against ischemia-reperfusion injury, in the mechanism of which CGRP may play a role.