Reduced coronary reactive hyperemia in mice was reversed by the soluble epoxide hydrolase inhibitor (t-AUCB): Role of adenosine A_2A receptor and plasma oxylipins

Coronary reactive hyperemia (CRH)protects the heart against ischemia. Adenosine A_2AAR–deficient (A_2AAR^−/−)mice have increased expression of soluble epoxide hydrolase (sEH); the enzyme responsible for breaking down the cardioprotective epoxyeicosatrienoic acids (EETs)to dihydroxyeicosatrienoic acids (DHETs). sEH–inhibition enhances CRH, increases EETs, and modulates oxylipin profiles. We investigated the changes of oxylipins and their impact on CRH in A_2AAR^−/− and wild type (WT)mice. We hypothesized that the attenuated CRH in A_2AAR^−/− mice is mediated by changes in oxylipin profiles, and that it can be reversed by either sEH- or ω-hydroxylases–inhibition. Compared to WT mice, A_2AAR^−/− mice had attenuated CRH and changed oxylipin profiles, which were consistent between plasma and heart perfusate samples, including decreased EET/DHET ratios, and increased hydroxyeicosatetraenoic acids (HETEs). Plasma oxylipns in A_2AAR^−/− mice indicated an increased proinflammatory state including increased ω-terminal HETEs, decreased epoxyoctadecaenoic/dihydroxyoctadecaenoic acids (EpOMEs/DiHOMEs)ratios, increased 9-hydroxyoctadecadienoic acid, and increased prostanoids. Inhibition of either sEH or ω-hydroxylases reversed the reduced CRH in A_2AAR^−/− mice. In WT and sEH^−/− mice, blocking A_2AAR decreased CRH. These data demonstrate that A_2AAR–deletion was associated with changes in oxylipin profiles, which may contribute to the attenuated CRH. Also, inhibition of sEH and ω-hydroxylases reversed the reduction in CRH.