Energy Utilization in Muscle Flashcards
What does creatine phosphate do for us in the body?
It buffers our ATP supply by giving ATP another phosphate when it uses one. It transfers a phosphate to ADP.
What does the liver do with protein and creatine phosphate?
Turns it into urea. The kidney then excretes it.
What are the 4 essential amino acids for building muscle?
- Selenocysteine
- Leucine
- L-Arginine
- Beta-Alanine
Why is Leucine so important? What about L-Arginine?
B-hydroxy-B-methylbutarate is a metabolite of the ketoacid formed from Leucine.
L-Citrilline is the metabolite of the keto acid from L-Arginine and is important as a cofactor for NOS.
L-Arginine also creates Creatine from its ketoacid.
What does AMPK do? What inhibits it?
AMP Activated Protein Kinase A creates ATP and AMP. During recovery, AMPK is reduced.
What is fatigue biochemically, particularly for type II fast twitch muscles?
Creatine phosphate is used in bursts (twitches) and then recovers between them. If you keep firing a fast twitch muscle without giving CP enough time to recover, you get fatigue.
What enzymes are linked to causing Rhabdo?
Myoadenylate deaminase (AMPD1)
Myophosphorylase (PYGM)
Carnitine Palmitoyl Transferase (CPT2)
What genes are linked to Rhabdo?
CKMM
ACTN3
MYLK (highest odds)
What 3 systems do we use for energy utilization?
Immediate - Creatine phosphate system for the first 15 seconds
Short term - First couple of minutes, using glycolysis
Long term - Aerobic system (TCA, etc)
We’ve discussed how immediate energy can come from Creatine phosphate as it gives a high energy phosphate to ADP to generate ATP and creatine. How do these values change in rest vs. work?
At rest, ADP is very low and phosphocreatine is way up. As we begin to exercise, we are using ATP, so we have a lot more ADP floating around and a reduced phosphocreatine since we begin to use it.
The ATP level does not change all that much, so the energy charge of the cell remains stable, hence we say the phosphocreatine system acts as a buffer to maintain ATP levels. Creatine goes way up as we exercise since we are doing the reaction.
Discuss the AMP kinase reaction during exercise
During exercise, we are depleting ATP as we generate it, and the ADP levels are rising because we are using ATP. AMP levels exponentially rise with increasing ADP because it isn’t really being put into any system.
This makes AMP the ideal signal to start up fuel catabolism
2ADP —> ATP + AMP
Discuss what is happening in our “anaerobic exercise”
Anaerobic means shut up mitochondria, we don’t need you.
Glucose (little comes in, most of it we get from glycogen) goes through glycolysis, spits out pyruvate, and then most of it goes to lactate where we can recycle NAD+ and send that lactate to the blood for energy
We use this in the initial period of exercise from a cold start, and in fast twitch white fibers and after aerobic max out.
Good rule of thumb for what rising ADP and AMP levels do due to exercise that drains ATP
ADP activates key steps inside the mitochondrial matrix
AMP activates key steps outside of the mitochondrial matrix
Discuss the importance of GLUT-4 and how we get it active
GLUT-4 is sensitive to insulin, which activates the transport of these guys to the plasma membrane to make them active.
Now the cell can get more glucose
During aerobic exercise, we want fatty acids to enter the mitochondria. How do we allow this to happen?
Keep in mind that the only thing really stopping these guys from going in is malonyl CoA which is blocking up CPT I.
Our two enzymes that regulate the impact of malonyl CoA on CPT I are Acetyl CoA carboxylase, which turns acetyl CoA into malonyl CoA, and Malonyl CoA decarboxylase, which turns malonyl CoA to Acetyl CoA.
When we exercise, AMP levels go up. This stimulates AMPK. What AMPK does it turns on the MCoA DC and turns off the ACC.
