PDHC physiology in oxidative tissues

Question 1

Oxidative tissues

Answer 1

primarily burning resources to make energy. (heart, skeletal muscle, even brain[brain will be the exception])

PDH +Pi/-Pi ratio regulation is best seen in these oxidative tissues. Brain is the exception bc brain cant rlly metabolize FA, not only due to the BBB…. brain will use glucose and ketone bodies (water soluble FA equivalents).

Means PDHC activity in brain is going to be high, because thats where your brain is going to be mostly using sugar, so PDHC is the way to connect sugar metabolism to TCA. ALways need it to be on, which means it will be in the dephospho form.

Question 2

If always in dephospho form, will PDHC be more or less highly regulated in brain/CNS?

Answer 2

Will be LESS regulated, because the brain needs constant sugar. Wants E1 to always be on.

Question 3

when liver has greattest glycolytic flux….

Answer 3

greatest glycolytic flux = PDHC will be dephosphorylated in fed state bc dont want Kinase phosphorylating E1 to inactivate it.

Fasting state will be the opposite.

Question 4

WHen liver has excessive amounts of sugar,

Answer 4

Would probably want to turn ofF PDHC

Question 5

Heart resting state….

Answer 5

Not doing a lot of activity, breaking down not a lot of fatty acids.
Will be phosphorylated in this state to keep you from using sugar.
B-ox does not require the PDHC to be function, bc produces acetyl-coA .

Question 6

Heart under workloads

Answer 6

If you are no longer in resting state, PDHC is mainly dephosphorylated, which means you will use glucose until fatty acids can be used.