TY - JOUR
T1 - Ischemic preconditioning prevents free radical production and mitochondrial depolarization in small-for-size rat liver grafts
AU - Rehman, Hasibur
AU - Connor, Henry D.
AU - Ramshesh, Venkat K.
AU - Theruvath, Tom P.
AU - Mason, Ronald P.
AU - Wright, Gary L.
AU - Lemasters, John J.
AU - Zhong, Zhi
PY - 2008/5
Y1 - 2008/5
N2 - 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 α-(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 ∼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.
AB - 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 α-(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 ∼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.
KW - Free radical
KW - Heat shock protein
KW - Ischemic preconditioning
KW - Mitochondrial permeability transition
KW - Partial liver transplantation
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U2 - 10.1097/TP.0b013e31816de302
DO - 10.1097/TP.0b013e31816de302
M3 - Article
C2 - 18475191
AN - SCOPUS:43449123052
SN - 0041-1337
VL - 85
SP - 1322
EP - 1331
JO - Transplantation
JF - Transplantation
IS - 9
ER -