BACKGROUNDWhether plasma can transfer the protective effect(s) of remote ischemic preconditioning (RIPC) between animals remains unresolved. We therefore investigated the effects of plasma collected 48 hours after transient limb ischemia on blood pressure recovery during myocardial ischemia reperfusion (IR) in homogenic rats.

METHODSPlasma was collected from Lewis rats, and the donor rats were randomly assigned to 2 groups: transient limb ischemia and control (n = 8 each). Transient limb ischemia was achieved by four cycles of 5-minute ischemia and 5-minute reperfusion by noninvasive ligation and deligation of the both legs using elastic rubber bands after anesthesia. In the control group, no ligation was performed. Forty-eight hours later, whole blood was collected, and the plasma spun off. Study Lewis rats underwent 30-minute left anterior descending coronary artery occlusion followed by 180-minute reperfusion, and were randomly assigned to 2 groups (group A and group B, n = 24 each), each further subdivided into 3 subgroups (n = 8 each). The subgroups of group A received normal saline (group A1) , plasma of control rats (group A2), plasma of transient limb ischemia rats (group A3) respectively at 1 hour before IR; the subgroups of group B received normal saline (group B1), plasma of control rats (group B2), plasma of transient limb ischemia rats (group B3) respectively at 24 hours before IR. BIOPAC systems were used to measure hemodynamics of rats during myocardial ischemiareperfusion.

RESULTSSystolic blood pressure (SBP) after IR in group B3 was different from that in groups B1 and B2 (B3 vs. B1, P = 0.007; B3 vs. B2, P = 0.039) at the beginning of reperfusion and 30 minutes after reperfusion. SBP was higher in group B3 than in groups B1 and B2 at the beginning of perfusion (B3 vs. B1, P = 0.010; B3 vs. B2, P = 0.002) and 30 minutes after reperfusion (B3 vs. B1, P = 0.001; B3 vs. B2, P = 0.001). SBP did not differ among subgroups A1, A2 and A3. Diastolic blood pressure and heart rate did not change in group A or group B.

CONCLUSIONSThe transfusion of plasma collected 48 hours after transient limb ischemia into homogenic rats 24 hours before IR can improve the SBP recovery during reperfusion. This may suggest that cardioprotective effect of late phase of RIPC is transferable via plasma.