Main function of ATP in muscle
Dissociation of actin-myosin complex
What does CK transfer?
a (P) from ATP --> Creatine
Type 1 muscle
Slow, Red, Fatigue resistant
High Mb and Mitochondria
Type 2a muscle
Type 2b Muscle
Fast, White, High glycogen and Low mitochondria
PFK2 difference in muscle? Why?
is NOT regulated by phosphorylation
It doesn't have the SERINE target for phosphorylation by PKA
Glucagon effect on muscle
none... there are no glucagon receptors
Glycogenolysis isn't stimulated by glucagon (only epi)
Fatty acid synthesis isoform in muscle
Acetyl-CoA Carboxylase II
FA metabolism is regulated by what in muscle?
Malonyl CoA (control CPT enzymes)
(AMP protein kinase is another important regulator)
In muscle, glycolysis is inhibited by
ATP and Citrate levels
PFK2 in cardiac muslce regulation
Phosphorylated and activated by insulin-depenent kinase cascade
Phosphorylation increases PFK2 kinase activity and STOPS glycolysis
3 ways that glycogen phosphorylase is regulated (activated)
- by AMP in muscle
- Ca++ can activate via glycogen phosphorylase kinase
- Epi can activate Adenylate cyclase, which activates cAMP-dependent protein kinase.
AMP activation pathway (2 steps)
- Atp---> ADP + Pi (((this happens during contraction)))
- 2ADP ---> ATP + AMP (((adenylate cyclase rxn)))
What is the "master metabolic regulator"?
AMP Protein Kinase (AMPPK)
Overall function of AMPPK
inhibits the processes that require ATP, stimulates the ones that produce ATP
4 important functions of AMPPK
- Induces GLUT4
- Inactivates AcetylCoA Carboxylase (and Increases Malonyl Decarboxylase)
- Inhibits HMG-CoA Reductase
- Activates PFK2 in cardiac muscle to increase glycolysis
Activates AMPPK via LKB1 (kinase)
How does is fatty acid entry into mitochondria affected by AMPPK?
It lowers AcetylCoA carboxylase 2 (isoform in muscle)
AND it increases Malonyl CoA carboxylase
**Both of these things mean there's a lot less Malonyl CoA floating around to inhibit CPT, so fatty acids get metabolized since they get transported into the mitochondria more readily.
Fatty acyl chains transported as...
Dephosphorylation effect on AcetylCoa Carboxylase?
What else regulates it?
It is inactivated by AMPPK and Palmitoyl CoA
Most abundant immediate source of ATP
Creatine synthesis pathway
- Glycine + Arginine -->> Guanidinoacetate + Ornithine
- Guanidinoacetate + SAM -->> Creatine + SAH
Where is creatine synthesized
Starts in Kidney, ends in liver
Creatinine synthesis pathway and properties
Creatine -->> CP -->> Creatinine -->> (Excreted in urine)
This is spontaneous, constant, and based on the amount of skeletal muscle mass.
Nonenzymatic cyclization in muscle and brain
Converted to Alanine by muscle for transport
What happens after lactate is taken up by other cells
it is converted to pyruvate by LDH
Anaerobic exercise progression
ATP generated from the formation of Lactate from glycogen
Rise in AMP = increase in PFK1 and glycogen breakdown = More ATP
- Lactate goes on to be used by heart after conversion to pyruvate
How much ATP from BCAAs?
Explain urine buffering in regards to BCAA
Release of NH3 by the muscle buffers urine as H+ increases during exercise