Mitigation of oxidative injury by classic and delayed ischemic preconditioning prior to small bowel autotransplantation.

ABSTRACT

Ischemic preconditioning (IPC) has been defined as short periods of ischemia with intermittent reperfusion. IPC induces two phases of protection. We sought to investigate the effects of classic and delayed preconditioning on oxidative stress markers prior to autotransplantation. Total orthotopic intestinal autotransplantation was performed on 18 mongrel dogs in three groups group I (GI, nonpreconditioned), group II (GII, classic preconditioned), and group III (GIII, delayed preconditioned). In GI 3-hour cold preservation in University of Wisconsin solution was followed by 1 hour of reperfusion. In GII before this procedure the intestine was preconditioned by occlusion of the mesenteric artery with four cycles each of 5 minutes of ischemia and 10 minutes of reperfusion (IPC protocol). In GIII on day 1 the animals underwent the IPC protocol, and autotransplantation was performed on day 2. Oxidative stress parameters included malondialdehyde (MDA), reduced glutathione (GSH), and superoxide dismutase (SOD) measurements in tissue samples. Our results showed increased lipid peroxidation with decreased GSH level and SOD activity in GI (control 254.38 +/- 18.32 IU/g; reperfused 55.01 +/- 26.40 IU/g; P <.05). In GII MDA was slightly elevated, and the GSH concentration was increased markedly. Furthermore, better preservation of SOD activity was observed at the end of the reperfusion. Meanwhile, in GIII GSH was significantly increased, indicating the activation of the endogenous antioxidant protective system (control 382.13 +/- 24.22 micromol/L per gram; reperfused 515.25 +/- 26.36 micromol/L per gram; P <.05). Moreover, SOD surpassed the control activity. Our findings confirmed that both forms of preconditioning mitigate the severity of oxidative stress prior to preservation and autotransplantation. Delayed preconditioning is more effective to protect bowel tissue against oxidative injury.