BACKGROUND: To evaluate the effects on lung ischaemia-reperfusion injury of ventilation with inspired oxygen concentrations of 0.21 and 1.00, and of allopurinol (an antioxidant). METHODS: Sixty Wistar rats were randomly allocated to six groups. Group I was the control group, while Groups II and III comprised the animals ventilated during ischaemia-reperfusion with 0.21 and 1.00 FiO2, respectively. The three remaining groups IA, IIA and IIIA were pre-treated with 100 mg/kg allopurinol and submitted to similar procedures as groups I, II and III respectively. The model used was normothermic ischaemia-reperfusion in situ. The duration of ischaemia was 30 minutes and that of reperfusion 10 minutes. Outcome measures included mean systemic arterial pressure (MAP), the partial pressure of oxygen/inspired fraction of oxygen (PaO2/FiO2) ratio, the level of thiobarbituric acid reactive substances (TBARS) in the lung tissue and the lung wet/dry weight ratio. RESULTS: There was a significant (p<0.05) decrease in the MAP among groups III x I, II x IIA and III x IIIA. With regard to the PaO2/FiO2 there was a significant (p<0.05) decrease between groups III x II and III x IIIA. The TBARS level showed a significant (p<0.05) reduction in group III compared to group IIIA. Meanwhile, there was a significant (p<0.05) increase in the lung wet/dry weight ratio comparing groups III x II, II x IIA and III x IIIA. CONCLUSION: Ventilation with 21% oxygen (FiO2=0.21), when compared to ventilation with 100% oxygen (FiO2 =1.0), resulted in a smaller decrease in MAP, an improved PaO2/FiO2 ratio and less pulmonary oedema. Compared to non-treated groups, the pre-treatement with allopurinol lead to a lower MAP decrease, an improved PaO2/FiO2 ratio, lower TBARS production and less pulmonary oedema.
Reperfusion; Oxygen free radicals; Lung; Allopurinol
