Alcohol Smooth endoplasmic reticulum

For most drugs, oxidative biotransformation is performed primarily by the mixed-function oxidase enzyme system, which is present predominantly in the smooth endoplasmic reticulum of the liver. This system comprises (1) the enzyme NADPH cytochrome P450 reductase (2) cytochrome P450, a family of heme-containing proteins that catalyze a variety of oxidative and reductive reactions and (3) a phospholipid bilayer that facilitates interaction between the two proteins. Important exceptions to this rule are ethyl alcohol and caffeine, which are oxidatively metabolized by enzymes primarily present in the soluble, cytosolic fraction of the liver. 

Adaptation to an alcohol intake of sufficient duration and quantity becomes morphologically visible when proliferation of the smooth endoplasmic reticulum as well as the Golgi complex is observed. This kind of induction can, for a certain period of time, only be detected with the aid of an electron microscope, but subsequently becomes visible under a light microscope as well. (s. pp 394, 544) (s. fig. 21.2)... 

The smooth endoplasmic reticulum contains enzymes involved in reactions of oxidation and hydroxylation of many types of molecules (alcohols, barbitiuates, antibiotics, steroid hormone synthesis and metabolism, etc.). These enzymes use cytochrome P450 and b as electron transport system and can also generate 02 and/or H2O2. 

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