Attenuation of postischemic microvascular disturbances by heat shock preconditioning in an isolated rat liver perfusion model

Background: Protective effects of heat shock (HS) preconditioning on postis chemic hepatic microcirculatory disturbances were investigated by intravita l fluorescence microscopy in an isolated liver perfusion model. Methods: The livers of Sprague-Dawley rats were flow-constantly perfused in situ with isogeneic rat blood for 120 minutes. Normothermic ischemia was i nduced by 30 minutes of no blood flow after cold flushing of the liver graf t. Heat shock preconditioning was induced by whole-body hyperthermia (42 de grees C for 15 minutes) and the subsequent 18 hours or 48 hours recovery. Results: In accordance with the enhanced expression of heat shock protein ( HSP) 70 and HSP32 in the liver tissue, the postischemic microvascular distu rbance (decrease in the sinusoidal perfusion rate, and increase in the numb er of stagnant leukocytes in sinusoids and in the number of adherent leukoc ytes in postsinusoidal venules) were significantly attenuated by HS precond itioning (p < 0.05). The postischemic deterioration of bile production and elevation of liver enzyme release were also significantly reduced (p < 0.05 ). Conclusion: These findings suggests that the cytoprotective effects of HS p reconditioning against postischemic injury might be attributable to the ind uction of HSP70 and HSP32.