Oestrogen-mediated cardioprotection following ischaemia and reperfusion is mimicked by an oestrogen receptor (ER)alpha agonist and unaffected by an ER beta antagonist.

Oestrogen protects the heart from ischaemic injury. The current study aims to characterise two novel oestrogen receptor (ER) ligands, an ER alpha agonist ERA-45 and an ER beta antagonist ERB-88, and then use them to investigate the roles of ER alpha and ER beta in mediating the cardioprotection by E from ischaemia-reperfusion injury in the rat. The ER ligands were characterised by gene transactivation assay using ER-transfected Chinese hamster ovary (CHO) cells and in bioavailability studies in vivo.

Medroxyprogesterone acetate inhibits the cardioprotective effect of estrogen in experimental ischemia-reperfusion injury.

Objective: Results from recent clinical trials of estrogen and progestogen therapy (EPT) suggest that some progestogens may interfere with the cardiovascular benefits of estrogen (E). The aim of this study was to investigate whether medroxyprogesterone acetate (MPA) modifies the protective effect of E in experimental ischemia-reperfusion (IR) injury in vivo and in vitro in the rat.

Design: Ovariectomized female Wistar rats (250-280 g, n = 61) received E, MPA, E and MPA, or placebo subcutaneously.