Role of endogenous hydrogen peroxide during angiotensin type 1 receptor blockers administration in pacing-induced metabolic coronary vasodilatation in dogs in vivo

Background: We have previously demonstrated that endothelium-derived hydrogen peroxide (H₂O₂) is an endothelium-derived hyperpolarizing factor (EDHF) in canine coronary microcirculation in vivo. However, the role of H₂O₂/EDHF during angiotensin type 1 receptor blockers (ARB) administration in metabolic coronary dilatation in vivo remains to be examined. We examined whether H₂O₂ during ARB administration is involved in pacing-induced metabolic coronary vasodilatation in dogs in vivo and if so, whether such beneficial effects of ARB administration acutely improve coronary vasodilatation in diabetes mellitus (DM).