THE ACTION OF p-AMINOPHENOL ON CERTAIN TISSUE OXIDATIONS

¹ From the Departments of Physiology and Pharmacology and Biochemistry, Duke University School of Medicine, Durham, North Carolina

1. Compared with a large number of similar substances p-aminophenol is the most active in inhibiting the oxygen uptake of liver suspension. It has no effect on the production of carbon dioxide.

2. The quinoid form of the drug is responsible for the inhibition. The optimum concentration is m/10,000.

3. The inhibition of the oxygen uptake of liver varies between 50 and 60 per cent at pH 6.4 and pH 6.7. Brain and kidney are inhibited 40 and 27 per cent respectively. There is no inhibition at pH 7.8.

4. A large number of substances which are oxidized by liver including succinate, lactate, amino acids, choline, tyramine and alcohol were unaffected by the quinoid form of p-aminophenol. But the oxidation of xanthine was inhibited completely by a concentration of m/20,000 at pH 6.4 and 6.7 and inhibited 50 per cent at pH 7.8.

5. Although related substances such as quinone and the oxidized forms of o-aminophenol and p-phenylene diamine inhibit the oxygen uptake of liver to a certain extent they have no effect on the oxidation of xanthine. The xanthine oxidase is thus specifically inhibited by p-aminophenol.

6. The significance of these results is discussed.