During a myocardial infarction, the oxygen supply to an area...

Name: Problem 1, Chapter :
Uploaded: 2020-12-24T19:05:12-08:00
Duration: 4 min 11 s
Channel: Dennis Howard
Description: During a myocardial infarction, the oxygen supply to an area of the heart is dramatically reduced, forcing the cardiac myocytes to switch to anaerobic metabolism. Under these conditions, which of the following enzymes would be activated by increased levels of intracellular AMP? (A) Succinate dehydrogenase (B) Phosphofructokinase- 1 (C) Isocitrate dehydrogenase (D) Pyruvate dehydrogenase

During a myocardial infarction, the oxygen supply to an area of the heart is dramatically reduced, forcing the cardiac myocytes to switch to anaerobic metabolism. Under these conditions, which of the following enzymes would be activated by increased levels of intracellular AMP? (A) Succinate dehydrogenase (B) Phosphofructokinase- 1 (C) Isocitrate dehydrogenase (D) Pyruvate dehydrogenase

During a myocardial infarction, the oxygen supply to an area of the heart is dramatically reduced, forcing the cardiac myocytes to switch to anaerobic metabolism. Under these conditions, which of the following enzymes would be activated by increased levels of intracellular AMP?
(A) Succinate dehydrogenase
(B) Phosphofructokinase- 1
(C) Isocitrate dehydrogenase
(D) Pyruvate dehydrogenase

Key Concepts

Anaerobic Metabolism

Anaerobic metabolism refers to metabolic processes that occur in the absence of oxygen. When oxygen is scarce, cells rely on anaerobic pathways, such as glycolysis, to generate ATP, the main energy currency. This shift is critical in tissues experiencing hypoxic stress, although it is less efficient than aerobic metabolism and often leads to the production of lactate.

Intracellular AMP

Intracellular AMP acts as a key indicator of a cell's energy state. When ATP consumption increases and energy levels drop, AMP levels rise. This increase in AMP signals the need for more ATP production, thereby activating metabolic pathways like glycolysis. AMP essentially functions as a metabolic alarm that triggers energy-generating processes.

Glycolysis

Glycolysis is a central metabolic pathway that breaks down glucose to produce ATP, pyruvate, and NADH. It is especially important during conditions of oxygen limitation, where it becomes the primary source of ATP through substrate-level phosphorylation. Glycolysis is tightly regulated to match cellular energy demands, ensuring a balance between energy supply and demand.

Phosphofructokinase-1 (PFK-1) Regulation

Phosphofructokinase-1 (PFK-1) is a key regulatory enzyme in the glycolytic pathway that catalyzes an early rate-limiting step. It is allosterically activated by AMP, which is elevated during low-energy states, and inhibited by ATP and citrate. This precise regulation ensures that glycolytic flux is increased when the cell requires more energy, particularly under anaerobic conditions.

Transcript

00:01 In order to answer this question, we have to be familiar with both the anaerobic and aerobic metabolism pathways.

00:10 So when we undergo this myocardial infarction, we find that the myocardial cells will be starved of oxygen, meaning that when there is low oxygen concentration or depleted oxygen concentration, they are going to switch over to anaerobic metabolic pathways or anabolic anaerobic respiratory pathways.

00:35 So this means that they are going to shift over from using their normal set of enzymes that they would use during normal aerobic conditions to using new enzymes that are going to be focused on the process of glycolysis, which is really the center.

00:55 Has a central role in the anaerobic process of cellular respiration.

01:01 So in order to answer the question, we have first discussed the differences here between anaerobic and aerobic respiration, but we now need to understand which enzymes specifically are going to be involved in each type of metabolic pathway.

01:17 So looking at our answer choices, we find that sussinate dehydrogenase, isocitrate, dehydrogenase, as well as pyruvate dehydrogenase, these are all going to be enzymes involved in aerobic metabolism.

02:02 So when oxygen is present in and is very abundant.

02:06 When we are undergoing anaerobic conditions, so when we are exposed to an oxygen depleted environment, these myocardial cells will be using pfk1.

02:28 And pfk1 is another name for phosphofructokinase 1.

02:38 So the question has been essentially answered, but let's just dive into what each of these enzymes does just to have an understanding of that...

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