Influence of ischemic preconditioning and nitric oxide on microcirculation and the degree of rat liver injury in the model of ischemia and reperfusion

The aim of this study was to assess the influence of ischemic preconditioning (IPC) on parenchymal liver blood flow during the early phase of reperfusion after 60 minutes of ischemia, additionally modified by adding N-nitro-L-arginine methyl ester (L-NAME). Our research involved 4 groups of rats (10 animals in each group), which underwent liver ischemia and 24 hours of reperfusion. Group I, ischemia/reperfusion (IR) was performed; group II, IPC, 10 minutes of ischemia and 10 minutes of reperfusion, and IR after that; group III, L-NAME (10 mg/kg intravenous [iv]), 10 minutes before IR; and group IV, L-NAME before IPC + IR. Activity of APAT, ALAT, GGTP, and FA was marked in serum in 90 minutes and 24 hours of reperfusion. In the liver biopsies at 24 hours of reperfusion, we analyzed reaction on adenosine-3-phosphatase stimulated by Mg++ and performed histological examination. The parenchymal perfusion was measured using a laser-doppler blood flowmeter (model PeriFlux System5000, Perimed Inc., United Kingdom). IPC during reperfusion led to minor injuries of the organ, with statistically significant normalization of enzymes compared with group I, and a better reaction to the adenosine-3-phosphatase IPC produced faster and full return of perfusion to the 68.3 value at 24 hours (59.1 in the 60 minutes). In groups III and IV at 60 minutes, the perfusion was not statistically different from that in group I. IPC causes full and faster blood return in the early phase of reperfusion and minor injury of liver parenchyma and liver sinus. The protective effect observed, especially in the first 60 minutes of reperfusion, was limited by L-NAME and was influenced by the action of nitric oxide.