Heat-shock preconditioning protects fatty livers in genetically obese Zucker rats from microvascular perfusion failure after ischemia reperfusion.

ABSTRACT

Reduced tolerance of steatotic livers to ischemic injury is considered to correlate with impaired microcirculation. The aim of this study was to investigate the impact of heat-shock preconditioning (HSPC) on microcirculatory failure after ischemia/reperfusion (I/R) in steatotic livers by means of intra-vital fluorescence microscopy. Obese Zucker rats were used. In the HS group, rats underwent whole-body hyperthermia followed by 60-min partial liver ischemia. In group IR, rats were exposed only to ischemia. Microcirculation parameters (sinusoidal perfusion rate, sinusoidal diameter, leukocyte-endothelial interaction) were significantly better preserved in the HS group than in the IR group. Liver enzymes, oxygenated glutathione/reduced glutathione (GSSG/GSH) ratio, and electron microscopy showed less damage in the HS group. A marked expression of heat shock protein 72 (HSP72) and heme oxygenase (HO-1) was found only in the livers of group HS. HSPC mitigated the I/R injury of steatotic livers by preventing post-ischemic failure of microcirculation. This beneficial effect was found to be associated with the induction of HSP72 and HO-1.