Effects of Diazonium Salts on Erythrocyte Fragility and Cholinesterase Activity

¹ From the Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee

Incubation of human erythrocytes in isotonic solutions containing diazonium salts (10^–5–10^–4m) results in an increased fragility of the treated cells. The degree of hemolysis is most marked when the red cells are suspended in solutions of electrolytes and much less in nonelectrolyte solutions. These findings suggest that the diazo compounds interfere specifically with cation transport processes. It was further observed that these compounds are rather potent inhibitors of cholinesterase, 50% inhibition being reached at a concentration of the order of 10^–5 m. Attempts to establish a causal relationship between enzyme inhibition and fragility change were unsuccessful. However, evidence was obtained which suggests that this enzyme system is involved in the process. Data are presented which suggest that the ionized phenolic hydroxyl group of the tyrosine residue may be an essential component of the active sites of the enzyme cholinesterase.