Pulmonary response to hyperoxia: effects of magnesium.

Animals and humans rapidly develop respiratory failure and die within a few days when exposed to 100% oxygen. Postmortem examination of the lungs shows histopathologic features characteristic of diffuse alveolar damage, clinically recognized as adult respiratory distress syndrome (ARDS). At the present time, there is no effective therapy available to alter outcomes in ARDS. Importantly, hypomagnesemia also is frequently observed in critically ill patients at risk of developing ARDS. In a model of hyperoxic lung injury, rats were exposed to 100% oxygen for 48, 64, and 96 hr and several experiments were performed. First, changes in the features of bronchoalveolar lavage and in alveolar macrophage function were compared in rats exposed to room air and those exposed to hyperoxia. Second, we studied the effect of hypomagnesemia on the severity of hyperoxic lung injury. Third, we evaluated the pulmonary responses to high-dose and normal-dose Mg therapy in rats exposed to hyperoxia. In all groups, hyperoxia indu...