Impairment of mitochondrial oxidative phosphorylation in rat fatty liver exposed to preservation-reperfusion injury.
OBJECTIVE
As the impairment of the cellular energy metabolism contributes to the failure of fatty liver grafts after transplantation, we aimed to determine whether steatosis affects the oxidative phosphorylation activity during preservation.


METHODS
Rat normal and fatty livers were preserved for 18 h and then reperfused with warm oxygenated solution. The oxidative phosphorylation, the F(0)F(1)-ATPase and the Complex I activities were assessed in isolated mitochondria before and after preservation, and during reperfusion. The ALT release and portal pressure were monitored during reperfusion.


RESULTS
The baseline phosphorylation activity was similar in normal and steatotic mitochondria. After cold preservation, the respiratory control index and state 3 respiration decreased significantly only in steatotic livers. Reperfusion induced a further deterioration in either group. Contrary to normal liver, uncoupling of fatty liver mitochondria allowed the recovery of the maximal respiration rate only using succinate (Complex II-dependent substrate), but not glutamate-malate (Complex I-dependent). Complex I dysfunction was confirmed spectrophotometrically. The ATPase activity was also significantly lower in fatty livers. Finally, ALT release and portal pressure were greater in steatotic livers.


CONCLUSIONS
The alteration of the oxidative phosphorylation activity during preservation is greatly exacerbated by fatty infiltration likely resulting from damage of the respiratory chain Complex I and of the F(0)F(1)-ATP synthase.
Caraceni
Paolo
P
Dipartimento di Biochimica, University of Bologna, 40138 Bologna, Italy. caraceni@med.unibo.it
Bianchi
Cristina
C
Domenicali
Marco
M
Maria Pertosa
Anna
A
Maiolini
Elisabetta
E
Parenti Castelli
Giovanna
G
Nardo
Bruno
B
Trevisani
Franco
F
Lenaz
Giorgio
G
Bernardi
Mauro
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure; D019069:Cell Respiration; D003080:Cold Temperature; D042967:Electron Transport Complex I / Q000378:metabolism; D005234:Fatty Liver / Q000378:metabolism* / Q000503:physiopathology; D016031:Liver Transplantation; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D028361:Mitochondrial Diseases / Q000378:metabolism* / Q000503:physiopathology; D009926:Organ Preservation; D011168:Portal System; D006180:Proton-Translocating ATPases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism* / Q000503:physiopathology; D014475:Uncoupling Agents / Q000494:pharmacology
D014475:Uncoupling Agents; D000255:Adenosine Triphosphate; D000410:Alanine Transaminase; D006180:Proton-Translocating ATPases; D042967:Electron Transport Complex I