Metabolic Fate of Lactate

Question 1

When is lactic acid produced?

Answer 1

Its always produced, even at rest.

Question 2

Does lactate cause fatigue or soreness?

Answer 2

No

Question 3

How is lactic acid formed?

Answer 3

Hydrogen and electrons from NADH are accepted by pyruvic acid. (adding a extra hydrogen from NADH to pyruvate)

Question 4

Why is lactate formed?

Answer 4

Because the rate of glycolysis is to fast and Krebs cycle can’t keep up.

Question 5

Who uses lactate as fuel?

Answer 5

Type II produces it and Type I uses it as fuel.

Question 6

What is lactate?

Answer 6

1. Not a waste product
2. Can be used as a high energy fuel (muscles, kidneys, heart)
3. Can be turned back into glucose (cori cycle)

Question 7

What is gluconeogenesis?

Answer 7

Formation of glucose from noncarbohydrate sources.

Question 8

What are the principal sources for gluconeogenesis?

Answer 8

Lactate
Pyruvate
Glycerol
Amino Acids

Question 9

How does lactate shuttle transport lactate to the mitochondria?

Answer 9

Reduced to pyruvate, converted to acetyl CoA, enters oxidative metabolism

Question 10

What happens if the mitochondrial hydrogen shuttle couldnt keep up with glycolysis?

Answer 10

1. Excess NADH in sarcoplasm favors conversion of pyruvic acid to lactic acid.
2. Type IIx fibers contain few mitochondria, so cannot clear lactate effectively.

Question 11

What is LDH?

Answer 11

Enzyme that converts pyruvic acid into lactic acid.