(melle-4)cyclosporin and Necrosis

Graft failure after liver transplantation may involve mitochondrial dysfunction. We examined whether prevention of mitochondrial injury would improve graft function. Orthotopic rat liver transplantation was performed after 18 hours' cold storage in University of Wisconsin solution and treatment with vehicle, minocycline, tetracycline, or N-methyl-4-isoleucine cyclosporin (NIM811) of explants and recipients. Serum alanine aminotransferase (ALT), necrosis, and apoptosis were assessed 6 hours after implantation. Mitochondrial polarization and cell viability were assessed by intravital microscopy. Respiration and the mitochondrial permeability transition (MPT) were assessed in isolated rat liver mitochondria. After transplantation with vehicle or tetracycline, ALT increased to 5242 U/L and 4373 U/L, respectively. Minocycline and NIM811 treatment decreased ALT to 2374 U/L and 2159 U/L, respectively (P < 0.01). Necrosis and terminal deoxynucleotidyl transferase-mediated nick-end labeling (TUNEL) also decreased from 21.4% and 21 cells/field, respectively, after vehicle to 10.1% and 6 cells/field after minocycline and to 8.7% and 5.2 cells/field after NIM811 (P < 0.05). Additionally, minocycline decreased caspase-3 activity in graft homogenates (P < 0.05). Long-term graft survival was 27% and 33%, respectively, after vehicle and tetracycline treatment, which increased to 60% and 70% after minocycline and NIM811 (P < 0.05). In isolated mitochondria, minocycline and NIM811 but not tetracycline blocked the MPT. Minocycline blocked the MPT by decreasing mitochondrial Ca(2+) uptake, whereas NIM811 blocks by interaction with cyclophilin D. Intravital microscopy showed that minocycline and NIM811 preserved mitochondrial polarization and cell viability after transplantation (P < 0.05).. Minocycline and NIM811 attenuated graft injury after rat liver transplantation and improved graft survival. Minocycline and/or NIM811 might be useful clinically in hepatic surgery and transplantation.

Topics: Adenosine Diphosphate; Alanine Transaminase; Animals; Anti-Bacterial Agents; Apoptosis; Calcium; Cyclosporine; Graft Survival; Liver; Liver Transplantation; Male; Minocycline; Mitochondria; Mitochondrial Diseases; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Necrosis; Rats; Rats, Inbred Lew; Reperfusion Injury; Tetracycline

ATP decreases markedly in small-for-size liver grafts. This study tested if the mitochondrial permeability transition (MPT) underlies dysfunction of small-for-size livers. Half-size livers were implanted into recipients of about twice the donor weight, resulting in quarter-size liver grafts. NIM811 (5 microM), a nonimmunosuppressive MPT inhibitor was added to the storage solutions. Mitochondrial polarization and cell death were assessed by confocal microscopy of rhodamine 123 (Rh123) and propidium iodide (PI), respectively. After quarter-size transplantation, alanine aminotransferase (ALT), serum bilirubin and necrosis all increased. NIM811 blocked these increases by >70%. After 38 h, BrdU labeling, a marker of cell proliferation and graft weight increase were 3% and 5%, respectively, which NIM811 increased to 30% and 42%. NIM811 also increased survival of quarter-size grafts. In sham-operated livers, hepatocytes exhibited punctate Rh123 fluorescence. By contrast, in quarter-size grafts at 18 h after implantation, mitochondria of most hepatocytes did not take up Rh123, indicating mitochondrial depolarization. Nearly all hepatocytes not taking up Rh123 continued to exclude PI at 18 h, indicating that depolarization preceded cell death. NIM811 and free radical-scavenging polyphenols strongly attenuated mitochondrial depolarization. In conclusion, mitochondria depolarized after quarter-size liver transplantation. NIM811 decreased injury and stimulated regeneration, probably by inhibiting free radical-dependent MPT onset.

Topics: Animals; Apoptosis; Cyclosporine; Electrophysiology; Graft Rejection; Hepatocytes; Hyperbilirubinemia; Ion Channels; Liver Regeneration; Liver Transplantation; Male; Mitochondria, Liver; Mitochondrial Proteins; Necrosis; Organ Size; Permeability; Rats; Rats, Inbred Lew; Uncoupling Protein 2

Brief periods of ischemia performed just at the time of reperfusion can reduce infarct size, a phenomenon called "postconditioning." After reflow, opening of the mitochondrial permeability transition pore (mPTP) has been involved in lethal reperfusion injury. We hypothesized that postconditioning may modulate mPTP opening.. Anesthetized open-chest rabbits underwent 30 minutes of ischemia and 4 hours of reperfusion. Control hearts underwent no additional intervention. Postconditioning consisted of 4 episodes of 1 minute of coronary occlusion and 1 minute of reperfusion performed after 1 minute of reflow after the prolonged ischemia. Preconditioning consisted of 5 minutes of ischemia and 5 minutes of reperfusion before the 30-minute ischemia. An additional group of rabbits received 5 mg/kg IV of NIM811, a specific inhibitor of the mPTP, 1 minute before reperfusion. Infarct size was assessed by triphenyltetrazolium staining. Mitochondria were isolated from the risk region myocardium, and Ca2+-induced mPTP opening was assessed by use of a potentiometric method. Postconditioning, preconditioning, and NIM811 significantly limited infarct size, which averaged 29+/-4%, 18+/-4%, and 20+/-4% of the risk region, respectively, versus 61+/-6% in controls (P< or =0.001 versus control). The Ca2+ load required to open the mPTP averaged 41+/-4, 47+/-5, and 67+/-9 micromol/L CaCl2 per mg of mitochondrial proteins in postconditioning, preconditioning, and NIM811, respectively, significantly higher than the value of 16+/-4 micromol/L per mg in controls (P< or =0.05).. Postconditioning inhibits opening of the mPTP and provides a powerful antiischemic protection.

Topics: Animals; Apoptosis; Calcium; Coronary Disease; Cyclosporine; Extracellular Signal-Regulated MAP Kinases; Ion Channel Gating; Ion Channels; Ion Transport; Male; MAP Kinase Signaling System; Membrane Potentials; Mitochondria, Heart; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Myocardial Infarction; Myocardial Ischemia; Myocardial Reperfusion Injury; Necrosis; Oxidative Stress; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Rabbits; Random Allocation; Time Factors