An investigation was made into the acute effects of ethanol and acetaldehyde with or without enzyme inhibitors of alcohol dehydrogenase (4-methylpyrazole) and aldehyde dehydrogenase (cyanamide) on fractional rates of protein synthesis of mixed and contractile proteins of the jejunum. Ethanol decreased the fractional rates of mixed and contractile protein synthesis (i.e. kodefined as the percentage of tissue protein renewed each day) by -25. Pretreatment with 4-methylpyrazole followed by treatment with ethanol further reduced mixed and contractile koby -30, when compared with saline plus saline and 4-methylpyrazole plus saline groups. The greatest reductions in koof mixed and contractile proteins occurred with cyanamide pretreatment followed by ethanol treatment: mixed and contractile protein koin the cyanamide plus ethanol group decreased by -60when compared with saline plus saline and cyanamide plus saline groups, whereas kodecreased by -45when compared with the saline plus ethanol injected group. Acetaldehyde treatment alone caused no significant inhibition of protein synthesis. However, 4-methylpyrazole pretreatment plus acetaldehyde treatment significantly reduced mixed and contractile koby -20when compared with the saline group, and by -15when compared with the 4-methylpyrazole plus saline and saline plus acetaldehyde groups. These data show that ethanol alone and perhaps high levels of acetaldehyde may be responsible for the inhibition of intestinal protein synthesis and related pathological derangements, e.g. motility disturbances due to loss of contractile proteins.
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