Ethanol Metabolism

Question 1

What are the two pathways for ethanol metabolism?

Answer 1

Liver alcohol dehydrogenase or Microsomal ethanol oxidizing system (MEOS)

Question 2

Describe the process of ethanol metabolism by the alcohol dehydrogenase.

Answer 2

Ethanol is broken down into acetaldehyde by the alcohol dehydrogenase, producing NAHD. Acetaldehyde is broken down into acetate by the Acetaldehyde dehydrogenase, also producing NADH. Acetate can then enter into TCA.\

Question 3

What enzymes are involved in the alcohol dehydrogenase mechanism of ethanol metabolism?

Answer 3

Alcohol Dehydrogenase & Acetaldehyde Dehydrogenase

Question 4

The buildup of what molecule is toxic and responsible for nausea, vomiting, headache, etc. associated with drinking?

Answer 4

Acetaldehyde

Question 5

What acetaldehyde dehydrogenase isoenzyme has a high affinity for acetaldehyde and is present in the mitochondria?

Answer 5

ALDH2

Question 6

Where is ALDH1 located?

Answer 6

Cytosol of the liver

Question 7

How does the microsomal ethanol oxidizing system metabolize ethanol?

Answer 7

The pathway is present in the liver and converts ethanol to acetaldehyde. The pathway uses cytochrome p450 enzymes and NADPH in the process.

Question 8

What is the fate of acetate in the liver and muscle tissues?

Answer 8

Acetate is converted to acetyl-CoA by the acetyl-CoA synthetase. In the muscles, acetyl-CoA enters into TCA. In the muscles, acetyl-CoA is used for cholesterol and FA synthesis.

Question 9

How does alcohol consumption contribute to low blood glucose levels?

Answer 9

Metabolism of ethanol produces NADH. In muscles acetate from ethanol metabolism is converted into acetyl-CoA, producing more NADH. The high amount of NADH mimics the “fed state” and prevents the release of glucose into the blood by the liver.