Modifications of coronary vascular reactivity due to a non‐enzymatic reaction between vitamin C and imidazole

Abstract

The objective of this study was to evaluate the role of superoxide (O2•−) resulting from the reaction between imidazole and vitamin C in altering the vascular reactivity of coronary arteries. It was hypothesized that a potential non‐enzymatic redox reaction between vitamin C and imidazole results in the production of O2•− and alters vascular reactivity. Left anterior descending coronary arteries (LAD) from porcine hearts were dissected, mounted in organ baths and passively loaded with 1.5 g of tension. Following a 5‐hour equilibration with control (Krebs‐Henseleit solution), vitamin C (2mM), imidazole (200mM), or combination of vitamin C and imidazole, LADs were treated with increasing concentrations of potassium chloride (KCl) and sodium nitroprusside (SNP) to assess changes in vascular reactivity. Incubation with the combination of vitamin C and imidazole as well as imidazole alone attenuated vascular responses to KCl and SNP. To detect the presence of O2•− in coronary arteries, a fluorescent dye‐based dihydorethidine (DHE) assay was utilized. An increase in the O2•− levels was observed in the arteries incubated with vitamin C and imidazole. The results from these studies may provide basic information on non‐enzymatic sources of superoxide in the vasculature and their effect on coronary artery function. This research was supported by a Grand Valley State University Presidential Grant.