14. Physical Activity and lipoprotein metabolism Flashcards
Discuss how triacylglycerol in the blood alters cholesterol transport
- Leads to increased TAG transported as VLDL
- –> TAG-rich VLDLs unload TAG onto HDLs and LDLs. TAG-rich HDLs are catabolised by the kidneys leading to fewer HDLs. Tag gets hydrolyses in TAG-rich LDLs leading to smaller and more dense LDLs
Describe the principle of the oral fat tolerance test (OFTT)
It determines the Postprandial Triglyceride levels after consumption of a meal.
Subjects either exercise or rest in the evening then have an evening meal. Come into the lab fasted then eat a standardised fat meal. Venous blood samples are taken every hour after the meal during the post prandial period.
The day after a 90 minute brisk walk, would you expect the data from an OFTT to alter and if so, how would it be after?
amount of TAG in the blood will begin lower and remain lower for the duration of the post prandial period.
Total lipaemic response was reduced.
What are the key mechanisms thought to be involved in changing lipid metabolism after exercise
Increased LPL activity (lipoprotein lipase) - endurance. Exercise increases insulin sensitivity therefore more LPL is activated.
- VLDL cholesterol can be transferred to HDL when TAG is cleared from VLDL by lipoprotein lipase
Training increases LCAT activity and decreases CETP activity - increasing reverse cholesterol transport.
What are the roles of CEPT and LCAT and how does this relate to cholesterol?
Cholesterols are polar so stick to the outside of the LDLs. When in circulation and the LDLs bump into other cell membranes the cholesterols can stick to that cell instead and prevent normal cell functioning.
LCAT and CEPT convert the cholesterols to cholesterol esters so that they are now non-polar, this means that they will no longer stick to the outside of the cell and will go on the inside, preventing cholesterol from being such a risk.
