Ischemic preconditioning prevents free radical production and mitochondrial depolarization in small-for-size rat liver grafts.

Abstract

BACKGROUND:

Ischemic preconditioning (IP) renders tissues more tolerant to subsequent longer episodes of ischemia. This study tested whether IP attenuates injury of small-for-size liver grafts by preventing free radical production and mitochondrial dysfunction.

METHODS:

IP was induced by clamping the portal vein and hepatic artery for 9 min. Livers were harvested 5 min after releasing the clamp. Mitochondrial polarization and cell death were assessed by intravital confocal/multiphoton microscopy of rhodamine 123 (Rh123) and propidium iodide. Free radicals were trapped with alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone and measured using electron spin resonance.

RESULTS:

After quarter-size liver transplantation, alanine aminotransferase, serum bilirubin, necrosis, and apoptosis all increased. IP blocked these increases by more than 58%. 5-Bromo-2'-deoxyuridine labeling and increases of graft weight were only approximately 3% and 0.2% in quarter-size grafts without IP, respectively, but increased to 32% and 60% in ischemic-preconditioned grafts, indicating better liver regeneration. Eighteen hours after implantation, viable cells with depolarized mitochondria in quarter-size grafts were 15 per high power field, and dead cells were less than 1 per high power field, indicating that depolarization preceded necrosis. A free radical adduct signal was detected in bile from quarter-size grafts. IP decreased this free radical formation and prevented mitochondrial depolarization. IP did not increase heat shock proteins 10, 27, 32, 60, 70, 72, 75 and Cu/Zn-superoxide dismutase (SOD) but increased heat shock protein-90, a chaperone that facilitates protein import into mitochondria, and mitochondrial Mn-SOD.

CONCLUSION:

Taken together, IP decreases injury and improves regeneration of small-for-size liver grafts, possibly by increasing mitochondrial Mn-SOD, thus protecting against free radical production and mitochondrial dysfunction.

• Authors: Hasibur Rehman, Henry D Connor, Venkat K Ramshesh, Tom P Theruvath, Ronald P Mason, Gary L Wright, John J Lemasters, Zhi Zhong
• Journal: Transplantation (Transplantation) Vol. 85 Issue 9 Pg. 1322-31 (May 15 2008) ISSN: 0041-1337 [Print] United States
• PMID: 18475191 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Aldehydes
• Free Radicals
• Proliferating Cell Nuclear Antigen
• Alanine Transaminase
• 4-hydroxy-2-nonenal
• Bilirubin

Topics

• Alanine Transaminase (blood)
• Aldehydes (analysis)
• Animals
• Bilirubin (blood)
• Free Radicals (adverse effects)
• Hepatic Artery
• Ischemic Preconditioning (methods)
• Liver Transplantation (methods)
• Male
• Models, Animal
• Portal Vein
• Proliferating Cell Nuclear Antigen (analysis)
• Rats
• Rats, Inbred Lew
• Transplantation, Isogeneic