Systemic ischemic preconditioning plus hemodilution enhanced early functional recovery of reperfused heart in the rabbits*1

We investigated whether transient systemic ischemia can precondition the heart against the ensuing ischemic insult. Rabbits were randomly divided into systemic ischemic preconditioning (SIP), hemodilution (HD) and control (C) groups. SIP was induced by rapidly withdrawing blood from femoral artery and maintaining the mean artery pressure at 50 mmHg for 10 min. Afterwards, 50% of the withdrawn blood was re-infused with equal volumes of 6% deferoxamine-conjugated hydroxyethyl-starch (D-HES). Hemodilution in HD group was achieved by withdrawing blood at 8 ml/kg accompanied by concomitant infusion of equal volumes of D-HES. Animals were subjected to 30 min of coronary artery occlusion followed by 120 min of reperfusion. Cardiac output (CO) (thermodilution method), plasma malondialdehyde and nitric oxide content were measured at baseline and until 120 (R120) min of reperfusion. At R120, CO in group-C was significantly lower than its baseline value, accompanied by a significant reduction in nitric oxide production and increase in malondialdehyde concentration; CO in group-SIP and group-HD maintained at baseline levels throughout reperfusion. At R120, CO in group-SIP, but not in group-HD, was significantly higher than that in group-C. It is concluded that transient SIP followed by hemodilution with D-HES facilitates early functional recovery of the ischemic-reperfused rabbit hearts.