Preischemic treatment with
atrial natriuretic peptide (
ANP) attenuates
ischemia-reperfusion injury of the rat liver via cyclic
guanosine monophosphate (cGMP). The attenuated activation of
nuclear factor kappaB (
NF-kappaB) seems to contribute to this effect. The aim of this study was to determine whether
heat shock proteins are involved in these molecular pathways. Livers of male Sprague-Dawley rats were continuously perfused with Krebs-Henseleit (KH)
buffer with or without
ANP or 8-Br-cGMP. In different experiments livers were perfused with or without
ANP for 20 minutes, kept in cold storage
solution for 24 hours, and reperfused. Activation of
heat shock transcription factor (HSF) (by electrophoretic mobility shift assay),
heat shock protein 70 (HSP70), and
glyceraldehyde phosphate dehydrogenase (GAPDH)
mRNA (by reverse transcription polymerase chain reaction [RT-PCR]), as well as HSP70 (by Western blot) were investigated in freeze-clamped liver samples. During continuous perfusion
ANP as well as 8-Br-cGMP activated HSF, HSP70
protein concentrations paralleled HSF-activation.
ANP pretreated livers exhibited elevated HSF after 24 hours of
ischemia and elevated HSP70
mRNA levels during reperfusion.
ANP prevented the marked decrease of HSP70
protein during reperfusion. Coimmunoprecipitation studies showed increased binding of HSP70 to inhibitory factor kappaB (IkappaB) in
ANP-treated livers. In conclusion, we showed the cGMP-mediated activation of HSF by
ANP, which resulted in elevated HSP70
mRNA and
protein concentrations and correlated with enhanced binding of HSP70 to IkappaB. This could be an important mechanism of
ANP-mediated prevention of hepatic preservation damage.