Hyperoxia (ventilation with FIO2 = 1.0) has
vasoconstrictor properties, in particular in the coronary vascular bed, and, hence, may promote cardiac dysfunction. However, we previously showed that
hyperoxia attenuated myocardial injury during
resuscitation from
hemorrhage in swine with
coronary artery disease. Therefore, we tested the hypothesis whether
hyperoxia would also mitigate myocardial injury and improve heart function in the absence of chronic cardiovascular comorbidity.After 3 h of
hemorrhage (removal of 30% of the calculated blood volume and subsequent titration of mean arterial pressure to 40 mm Hg) 19 anesthetized, mechanically ventilated, and instrumented pigs received FIO2 = 0.3(control) or
hyperoxia(FIO2 = 1.0) during the first 24 h. Before, at the end of and every 12 h after
shock, hemodynamics, blood
gases, metabolism,
cytokines, and cardiac function (pulmonary artery thermodilution, left ventricular pressure-conductance catheterization) were recorded. At 48 h, cardiac tissue was harvested for western blotting, immunohistochemistry, and mitochondrial respiration.Except for higher left ventricular end-diastolic pressures at 24 h (
hyperoxia 21 (17;24), control 17 (15;18) mm Hg; P = 0.046),
hyperoxia affected neither left ventricular function cardiac injury (max.
Troponin I at 12 h:
hyperoxia:9 (6;23), control:17 (11;24) ng mL; P = 0.395), nor plasma
cytokines (except for
interleukin-1β:
hyperoxia 10 (10;10) and 10 (10;10)/control 14 (10;22), 12 (10;15) pg mL, P = 0.023 and 0.021 at 12 and 24 h, respectively), oxidation and nitrosative stress, and mitochondrial respiration. However,
hyperoxia decreased cardiac tissue three-
nitrotyrosine formation (P < 0.001) and
inducible nitric oxide synthase expression (P = 0.016). Ultimately, survival did not differ significantly either.In conclusion, in contrast to our previous study in swine with
coronary artery disease,
hyperoxia did not beneficially affect cardiac function or tissue injury in healthy swine, but was devoid of deleterious side effects.