Activation of phospholipases releases free arachidonic acid (ARA) from phospholipid bilayers which can then be metabolised to biologically active eicosanoids (signaling molecules which exert effects in inflammation and immunity). The cytochrome P450 enzyme CYP2J2 (arachidonic acid epoxygenase) is mainly expressed in human heart and can metabolise ARA to epoxyeicosatrienoic acid (EET). Four cis-EETs can be produced: 5,6-, 8,9-, 11,12- and 14,15-EET. Each of these can be formed as the R,S or the S,R enantiomer (Zeldin DC, 2001). The most abundant regioisomer in human heart is 14,15-EET although 11,12-EET possesses the most potent anti-inflammatory effect (Wu et al. 1996).