Remote ischemic preconditioning differentially affects NADPH oxidase isoforms during hepatic ischemia-reperfusion.
OBJECTIVE
We investigated the function of major superoxide-generating enzymes after remote ischemic preconditioning (IPC) and hepatic ischemia-reperfusion (IR), with the specific aim of assessing the importance of the most relevant NADPH oxidase (NOX) isoforms, NOX2 and NOX4, in the mechanism of action.


METHODS
60-min partial liver ischemia was induced in Sprague-Dawley rats in the presence or absence of remote IPC (2 × 10-min limb IR), and hepatic microcirculatory variables were determined through intravital video microscopy and lightguide spectrophotometry during reperfusion. Inflammatory enzyme activities (myeloperoxidase (MPO) and xanthine oxidoreductase (XOR)), cytokine production (TNF-α and HMGB-1), liver necroenzyme levels (AST, ALT and LDH) and NOX2 and NOX4 protein expression changes (Western blot analysis) were assayed biochemically.


RESULTS
In this setting, remote IPC significantly decreased the IR-induced hepatic NOX2 expression, but the NOX4 expression remained unchanged. The remote IPC provided significant, but incomplete protection against the leukocyte-endothelial cell interactions and flow deterioration. Hepatocellular damage (AST, ALT and LDH release), cytokine levels, and XOR and MPO activities also diminished.


CONCLUSIONS
Remote IPC limited the IR-induced microcirculatory dysfunction, but the protective effect did not affect all NOX homologs (at least not NOX4). The residual damage and inflammatory activation could well be linked to the unchanging NOX4 activity.
Institute of Surgical Research, University of Szeged, Szeged, Hungary.
Dénes
D
Garab
Institute of Laboratory Animal Science and Experimental Surgery, RWTH Aachen University, Aachen, Germany.
Ngwi
N
Fet
Institute of Surgical Research, University of Szeged, Szeged, Hungary.
Andrea
A
Szabó
Institute of Laboratory Animal Science and Experimental Surgery, RWTH Aachen University, Aachen, Germany.
René H
RH
Tolba
Institute of Surgical Research, University of Szeged, Szeged, Hungary.
Mihály
M
Boros
Institute of Surgical Research, University of Szeged, Szeged, Hungary. Electronic address: hartmann.petra@med.szote.u-szeged.hu.
Petra
P
Hartmann
D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D016207:Cytokines / Q000097:blood; D024243:HMGB1 Protein / Q000378:metabolism; D019194:Ischemic Preconditioning / Q000379:methods*; D008099:Liver / Q000098:blood supply / Q000201:enzymology*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008833:Microcirculation / Q000502:physiology; D018715:Microscopy, Video; D000074662:NADPH Oxidase 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000378:metabolism*; D009195:Peroxidase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000201:enzymology*; D013053:Spectrophotometry; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014968:Xanthine Dehydrogenase / Q000378:metabolism
D016207:Cytokines; D024243:HMGB1 Protein; D008562:Membrane Glycoproteins; D014409:Tumor Necrosis Factor-alpha; D009195:Peroxidase; D014968:Xanthine Dehydrogenase; C500593:Cybb protein, rat; D000074662:NADPH Oxidase 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498911:Nox4 protein, rat
Inflammation; Intravital video microscopy; Microcirculation; Modified spectrophotometry; NOX2; NOX4; Polymorphonuclear leukocytes