Hypoxanthine levels of plasma during hypoxemia in dogs.

Tissue hypoxia was induced in one group of dogs by clamping of the endotracheal tube and in another group by artificial ventilation with a mixture of nitrogen and air. The hypoxanthine concentration of venous and arterial plasma increased significantly during severe hypoxemia. When the hypoxemia was relieved, an increased venous-arterial hypoxanthine difference appeared indicating that the lung metabolism of hypoxanthine was slowed down during alveolar hypoxia. It is concluded that the level of plasma hypoxanthine in dogs during hypoxemia is dependent on the degree of tissue hypoxia, peripheral vasoregulation, and lung metabolism.