Cardiac microdialysis of salicylic acid to detect hydroxyl radical generation associated with sympathetic nerve stimulation

Abstract

We examined the relationship between norepinephrine (NE) and hydroxyl free radical ( dotOH) generation on cardiac nerve stimulation. Salicylic acid in Ringer's solution (0.5 nmol,μl −1 min −1) was infused directly through a microdialysis probe to detect the generation of hydroxyl radicals ( dotOH) as reflected by the formation of dihydroxybenzoic acid (DHBA) in the myocardium of anesthetized rats. Sympathetic nerve stimulation increased the release of NE and the formation of DHBA. A positive linear correlation between the release of NE and the formation of 2,3-DHBA ( R 2 = 0.982) or 2,5-DHBA ( R 2 = 0.976) was observed. These data indicate that the sustained elevation of NE in the extracellular fluid can be auto-oxidized, which in turn leads (possibly by an indirect mechanism) to the formation of cytotoxic dotOH free radicals.