Chronic in vivo sodium azide infusion induces selective and stable inhibition of cytochrome c oxidase.

The effect of chronic subcutaneous infusion of sodium azide on the activity of mitochondrial respiratory chain enzymes was investigated in Sprague-Dawley rats. Treatment with approximately 1 mg/kg/h sodium azide induced chronic, partial inhibition of cytochrome c oxidase, whereas the activities of respiratory complexes I and III were not significantly affected. The inhibition of cytochrome c oxidase was evident by 7 days after infusion began, and the effect was stable for at least 3 weeks. The selectivity of azide for cytochrome c oxidase is discussed in the context of other findings of azide effects on enzymes. The results of the present study indicate that the sodium azide infusion paradigm described here provides a useful tool for the evaluation of selective and stable cytochrome oxidase inhibition in vivo.