Melatonin attenuates posttransplant lung ischemia-reperfusion injury.
BACKGROUND
Melatonin, a pineal hormone, is a free radical scavenger and an antioxidant. The purpose of this study was to assess the protective effect of melatonin on posttransplant lung ischemia-reperfusion injury.


METHODS
Rat single-lung transplantation was performed in two (n = 10) experimental groups after 18 hours of cold (4 degrees C) ischemia. Group I animals consisted of the ischemic control group. In group II, donor and recipient animals were treated with intraperitoneal injection of 10 mg/kg melatonin 10 minutes before harvest and reperfusion, respectively. After 2 hours of reperfusion, oxygenation, plasma, and bronchoalveolar lavage nitrite levels were measured. Lung tissue was assessed for thiobarbituric acid reactive substances and myeloperoxidase activity. Peak airway pressure was recorded throughout the reperfusion period.


RESULTS
The melatonin-treated group showed significantly better oxygenation (321.8+/-33.8 mm Hg versus 86.1+/-17.4 mm Hg; p < 0.001), reduced lipid peroxidation (0.65+/-0.3 nmol/g versus 1.63+/-0.8 nmol/g; p = 0.032), and reduced myeloperoxidase activity (0.56+/-0.1 deltaOD x mg(-1) x min(-1) versus 1.01+/-0.2 deltaOD x mg(-1) x min(-1); p = 0.032). Bronchoalveolar lavage nitrite levels in the transplanted lungs were significantly lower in group II than in group I (0.34+/-0.06 micromol/L versus 1.65+/-0.6 micromol/L; p = 0.016). In group II significant reduction in peak airway pressure was noted compared with group I (p = 0.002).


CONCLUSIONS
In this model, exogenously administered melatonin effectively protected lungs from reperfusion injury after prolonged ischemia.
Inci
Ilhan
I
Divisions of Thoracic Surgery and Pulmonary Medicine, University Hospital, and Children's Hospital, University of Zurich, Switzerland.
Inci
Demet
D
Dutly
André
A
Boehler
Annette
A
Weder
Walter
W
D000818:Animals; D000975:Antioxidants / Q000627:therapeutic use*; D016166:Free Radical Scavengers / Q000627:therapeutic use*; D015227:Lipid Peroxidation; D016040:Lung Transplantation / Q000009:adverse effects; D008550:Melatonin / Q000627:therapeutic use*; D023421:Models, Animal; D009195:Peroxidase / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D011916:Rats, Inbred F344; D015427:Reperfusion Injury / Q000517:prevention & control*; D017392:Thiobarbituric Acid Reactive Substances
D000975:Antioxidants; D016166:Free Radical Scavengers; D017392:Thiobarbituric Acid Reactive Substances; D009195:Peroxidase; D008550:Melatonin