The Effect of Superoxide Generation by Ascorbic Acid and Imidazole on Coronary and Pulmonary Arteries

Abstract

The purpose of this study was to evaluate the responses of coronary and pulmonary arteries to the generation of superoxide (O2.) via organic redox complex formation between ascorbic acid and imidazole. Imidazole facilitates the transfer of electrons from ascorbic acid to O2 resulting in the generation of O2. Using a Clark style electrode, oxygen levels were monitored in solutions of ascorbic acid and imidazole and decreasing oxygen levels were used as an indication of O2. generation. In another series of experiments, small rings of porcine coronary and pulmonary arteries were dissected, mounted in isolated organ baths, and administered increasing concentrations (10−8–10−3 M) of ascorbic acid, glycine, imidazole, or ascorbic acid and imidazole. Vascular responses were recorded as changes in tension. The combination of ascorbic acid and imidazole, but not ascorbic acid or glycine, caused a significant vasoconstriction in both coronary and pulmonary arteries. Imidazole induced vasoconstriction in coronary arteries. Taken together, these results suggest that ascorbic acid in the presence of imidazole may increase O2. production resulting in an increase in tension in coronary and pulmonary arteries. This research was supported by a Grand Valley State University Research Grant‐in‐Aid.