RESUMO
We compared the responses towards oxidative stress in the liver, lung, brain, heart, kidney and small intestine of hypoxic newborn animals resuscitated with 21% or 100% oxygen. After stabilization, piglets (1-3 days, 1.6-2.0 kg, n=8/group) were randomized to receive 2 h of alveolar hypoxia (FiO(2)=0.10-0.14) followed by reoxygenation with 21% or 100% oxygen for 1 h and then another hour with 21% oxygen. Controls were sham-operated without hypoxia-reoxygenation. At the end of the experiment, tissues from liver, lung, brain, heart, kidney and small intestine were collected and tested for GSH, GSSG and lipid peroxidation levels and histological examination. In normoxic controls, liver had the highest GSH level, followed by brain, heart, lung, small intestine and kidney which had the highest level of oxidative stress markers (GSSG level and GSSG:GSH ratio). Hypoxic-reoxygenated piglets had the highest GSSG levels and GSSG:GSH ratio in the kidney. Hypoxic piglets resuscitated with 100% oxygen had higher GSSG:GSH ratios in the lung and liver, but not in the kidney, brain, heart and small intestine, than controls, which were not different from the 21% group. No significant differences in peroxidation and histological tissue damage were found between groups in the liver and lung. We concluded that although hypoxic piglets resuscitated with 100% oxygen have higher oxidative stress in the liver and lung than with 21% oxygen, there are no significant differences in peroxidation and histological tissue damage acutely.