The in vitro effects of sodium azide on tissues of normal and thyroid-fed rats.

Sodium azide has been employed as a metabolic inhibitor in a variety of studies. Stannard has described the use of this agent in distinguishing between the oxygen consumption of resting as opposed to working frog muscle (1). The increased respiration due to activity was abolished by azide, while the basal resting value was unaffected. Azide has also been shown to interfere with the phosphorylations accompanying oxidative metabolism (2). It was decided to apply these same measurements to the isolated tissues of animals rendered hyperthyroid, to determine whether the thyroid-induced increase in metabolic rate could similarly be distinguished from the rate at resting levels, and whether this was reflected in changes in energy phosphorylations. Similarities in the stimulatory effects of work as compared with thyroid excess might aid in outlining the metabolic site of action of the thyroid hormone.