Heart 7-hydroperoxycholesterol and oxysterols are elevated in chronically ethanol-fed rats

Recently, cholesterol hydroperoxides have been shown to be sensitive pathogenic markers of reactive oxygen species (ROS)-mediated damage though they have never been measured in heart tissue. We hypothesized that cholesterol hydroperoxides and oxysterols, putative cardiotoxic products of cholesterol oxidation, are elevated in the hearts of alcoholics as a consequence of ROS-mediated reactions. To test this, we measured 7 alpha- and 7 beta -hydroperoxycholest-5-en-3 beta -ol (7 alpha -OOH and 7 beta -OOH) by HPLC with postcolumn chemiluminescence as well as 7 alpha- and 7 beta -hydroxycholesterol (7 alpha -OH and 7 beta -OH) and 3 beta -hydroxycholest-5-en-7-one (also termed 7-ketocholesterol; 7-keto) by HPLC-UV in cardiac muscle of alcohol-fed rats. Alcohol feeding was carried out using a pair-feeding protocol with 35% of total dietary energy as ethanol; controls were pair-fed isocaloric glucose. After 6-7 wk treatment with alcohol, heart 7 alpha -OOH, 7 beta -OOH and 7 beta -OH were significantly greater than in controls. Levels of heart phospholipid 16:0 and 18:1 were lower than in controls, while-18:0 and 18:2 were greater. This is the first report of the presence of 7a-OOH, 7 beta -OOH and 7a-OH in cardiac tissue. The elevations in 7 alpha -OOH and 7 beta -OOH as well as 7 beta -OH are evidence of increased oxidative stress and possible membrane changes. Alterations in the proportions of 16:0, 18:1, 18:2 and 18:0 in heart phospholipids provide further evidence of an altered membrane domain.