Effect of Thyroid Hormone on the Ischemia-Reperfusion Injury in the Canine Lung

Kim, Young Tae; Sung, Sook Whan

Abstract

BACKGROUND: Ischemia-reperfusion injury is one of the major contributing causes of early graft failure in lung transplantation. It has been suggested that triiodothyronine (T3) may ameliorate ischemia-reperfusion injury to various organs in vivo and in vitro. Predicting its beneficial effect for ischemic lung injury, we set out to demonstrate it by administering T3 into the in situ canine ischemia-reperfusion model. MATERIAL AND METHOD: Sixteen adult mongrel dogs were randomly allocated into group A and B. T3 (3.6 microgram/kg) was administered before the initiation of single lung ischemia in group B, whereas the same amount of saline was administered in group A. Ischemia was induced in the left lung by clamping the left hilum for 100 minutes. After reperfusion, various hemodynamic parameters and blood gases were analyzed for 4 hours while intermittently clamping the right hilum in order to allow observation of the injured left lung function. RESULT: Arterial oxygen partial pressure (PaO2) decreased 30 minutes after reperfusion and recovered gradually thereafter in both groups. In group B the decrease of PaO2 was less marked than in group A. The recovery of PaO2 was faster in group B than in group A. The differences between the two groups were statistically significant from 30 minutes after reperfusion (125+/-34 mmHg and 252+/-44 mmHg, p<0.05) until the end of the experiment (178+/-42 mmHg and 330+/-37 mmHg, p<0.05). The differences in the arterial carbon dioxide pressure, airway pressure and lung compliance showed no statistical significance. The malondialdehyde (MDA) level, measured from the tissue obtained 240 minutes after reperfusion, was lower in group B (0.40+/-0.04 micrometer) than in group A (0.53+/-0.05 micrometer, p<0.05). The ATP level of group B (0.69+/-0.07 micrometer/g) was significantly higher than that of group A (0.48+/-0.07 micrometer/g, p<0.05). The microscopic exami nation revealed varying degrees of injury such as perivascular neutrophil infiltration, capillary hemorrhage and interstitial congestion. There were no differences in the microscopic findings between the two groups. CONCLUSION T3 has beneficial effects on the ischemic canine lung injury including preservation of oxygenation capacity, less production of lipid peroxidation products and a higher level of tissue ATP. These results suggest that T3 is effective in pulmonary allograft preservation.