Lecture 8 - Protein Metabolism and Exercise Flashcards
It is quite easy to label…
plasma glucose - can differentiate from glycogen oxidation
carbon 13 is stable but not…
radioactive (unlike carbon 14)
During endurance exercise, all glucose that is taken up from the circulation is ______
oxidised
Plasma glucose oxidation during exercise can also be determined by…
measuring the uptake of (6,6-2h2)-glucose
The large majority of metabolism during high intensity comes from …
muscle glycogen
not much fat
What do you measure AA oxidation?
Nitrogen balance, Plasma Urea, Urea in urine (very crude, no fine detail)
These measures only give a general idea
Each AA has it’s own specific….
metabolism
You should always use ______ AAs for tracing purposes
essential
Glucose-Alanine Cycle involves:
Breakdown of Alanine to Pyruvate –> Glucose in the liver
once arrives at msucle can enter TCA cycle.
Alanine in the muscle can be transferred to the liver to provide an AA source for this process
AAs can enter the TCA cycle at ______ points
different - all needed to keep the cycle going
Oxidation rate of leucine is much higher than ____
phenalalanine - Oxidatioin rate of AAs is different
Exercise increases leucine oxidation, but not _________ oxidation
phenylalanine oxidation - the oxidation rate of AAs is different
What effect does exercise have on urea production
none - it does not increase
Protein intake has more profound effect on urea production than exercise
Using beta-adrenergic blockage during exercise what happened?
Reduced FFA/Glycogen availability
reduced glycogen utilisation
**Increases Leucine oxidation
under normal conditions the use of Leucine is.
suppressed by other fuels
Availability of glycogen influences the use of leucine during exercise, however…
contribution to total energy expenditure remains very small
Using stable isotope methodology we can …
assess plasma glucose and FFA oxidation and determine the contribution of the different substrate stores to energy expenditure
In what way do AAs play a role in energy metabolism?
Each AA has its own specific metabolism
Glutamate is important to maintain TCA intermediates to allow maximal rates of FFA oxidation
Alanine is produced in muscle during exercise and transported to the liver for gluconeogenesis and urea production
Leucine, but not phenylalanine, oxidation is increased during exercise
Name 3 essential AAs
Leucine, isoleucine, valine
