Acute effect of ethanol on 7-hydroperoxycholesterol in muscle and liver

We tested the hypotheses that ethanol sensitivities of muscle and liver can be discerned in the initial periods of ethanol exposure, especially when a cetaldehyde levels are markedly raised with cyanamide an aldehyde dehydroge nase inhibitor. To test this, we measured cholesterol hydroperoxides in sol eus (Type I) and plantaris (Type II) muscle in four groups of rats acutely (i.e., 2.5 h) exposed to: [S] saline (control), [Cy] cyanamide, [EtOH] etha nol, or [Cy + EtOH] cyanamide + ethanol. Comparative reference was also mad e to the response of the liver. After 2.5 h, ethanol alone significantly in creased 7 alpha -hydroperoxycholest-5-en-3 beta -ol (7 alpha -OOH) and 7 be ta -hydroperoxycholest-5-en-3 beta -ol (7 beta -OOH) levels in plantaris mu scle. Identical qualitative effects were seen in rats treated with cyanamid e + ethanol, but there was no discernible difference between groups [EtOH] and [Cy + EtOH]. In both the soleus muscle and liver, none of the treatment s with either ethanol or cyanamide + ethanol had any effect on any of the m easured parameters. This is the first report of a differential response of 7 alpha -OOH and 7 beta -OOH in Type II, compared to Type I predominant mus cles, and the first time that muscle has been shown to be more sensitive th an the liver in terms of its lipid marker response to oxidative stress. Per turbations in the muscle membrane lipid domain may contribute to impairment of muscle in alcoholism.