Effect of .OH scavenging action by non-SH-containing angiotensin converting enzyme inhibitor imidaprilat using...

We examined the effect of non-SH-containing angiotensin converting enzyme (ACE) inhibitor imidaprilat on hydroxyl radical (.OH) generation using microdialysis. Salicylic acid in Ringer's solution containing sodium salicylate (0.5 n mol microL-1 min-1) was infused directly through a microdialysis probe to detect the generation of .OH as reflected by the formation of 2,3-dihydroxybenzoic acid (DHBA) in the myocardium of anesthetized rats. We compared the ability of two non-SH-containing ACE inhibitors (imidaprilat and enalaprilat) with an -SH-containing ACE inhibitor (captopril) to scavenge the .OH. When iron (II) was administered to animals pretreated with these three ACE inhibitors, a decrease in 2,3-DHBA of all three compounds was observed, as compared with the iron (II) only-treated group. All three ACE inhibitors were able to scavenge .OH generated by the action of iron (II). However, imidaprilat is a free radical scavenger more potent than enalaprilat. These results suggested that ACE inhibitors are probably not only related to the presence of the SH radical.