Vascular Physiology Seminar Flashcards
How does endurance training affect humans?
Endurance exercise training induces a dramatic increase in muscle capillarity of humans.
How does increased capillary supply affect humans?
An increased capillary supply improves respiratory gas exchange and substrate/ metabolite exchange by providing a greater surface area, increase time in the capillaries and reduced distances for diffusion.
What is the difference between arteriogenesis and angiogenesis?
Arteriogenesis is the enlargement of existing arterial vessels by increase in diameter and wall thickness. It occurs due to increase in strain on the vessel wall
Angiogenesis is the formation of new capillaries from preexisting vessels
What is collateralisation?
Collateralisation is the opening up of existing vessels to provide a conduit around occlusions
What is capillary arterialisation?
Capillary arterialisation is the maturation of microvessels where the endothelial tube is covered with vascular smooth muscle cells
What is vasculogenesis?
Vasculogenesis is the creation of new blood vessels during embryological development
What is a cytokine?
A small protein released by cells that has a specific effect on the interactions between cells, on communications between cells or on the behavior of cells. The cytokines includes the interleukins, lymphokines and cell signal molecules, such as tumor necrosis factor and the interferons, which trigger inflammation and respond to infections.
What does VEGF do?
Stimulates endothelial cell and vascular smooth muscle cell proliferation and migration, promotes EC survival and differentiation, induces capillary permeability and arteriolar vasodilation
Main signal for muscle activity
Needs other signals- VEGF alone does not induce angiogenesis in ischaemia
Where is VEGF produced?
Endothelial cells, perivascular cells, host tissue cells e.g. skeletal muscle
Where does VEGF act?
Through endothelial cell specific receptor tyrosine kinases
What are the important research points associated with VEGF?
Important in muscle capillary supply in exercise
Gene ablation VEGF and its receptor essential for normal vascular development
Correlation betweenVEGFR2 receptor protein levels and capillary growth in activity and hypoxia
What does Placental Growth Factor (PlGF) do?
Role in pathological angiogenesis eg tumour, arthritis, and atherosclerosis
No role in exercise
Where does PlGF act?
FLT1 receptor- type of VEGF
What do angiopoietins do?
Modulate vessel development and remodelling, Ang1-maturation of new vessels, stabilise vascular network
Ang 2- promotes vascular remodelling by facilitates growth factors and vascular regression in absence of signal
Where do angiopoietins act?
Through receptor tyrosine kinases
What are the important research points associated with angiopoietins?
Ratio of Ang2/Ang1 is elevated after exercise- promote action of VEGF?
What does Nitric oxide do?
Mediates effects of VEGF.
Mediates VEGF vasodilation and vascular permeability
VEGFR2 stimulates NO production- reciprocal
NO stimulates VEGF expression
Mediates vasodilation with VEGF
Inhibits angiostatin
Cell growth in endothelium
Where is nitric oxide produced?
Endothelial Cells by endothelial nitric oxide synthase
Muscle fibres?
What are the important research points associated with nitric oxide?
When inhibited angiogenesis still occurs
Produced in exercise
Blockage of eNOS stops stimuli such as electrical stimulation - Block synthesis prevents VEGF effects
May improve capacity for remodelling
Inhibit enzyme production doesn’t stop angiogenesis but may relate to shear stress
May be released by contracting muscles
Exercise increased eNOS mRNA and eNOS
Chronic activity increases eNOS- improved capacity for vascular remodelling and fitness
NO released by muscle fibres from nNOS contributing to exercise angiogenesis
Inhibition of NO production does not prevent angiogenesis in flow restricted muscles- may need high shear stress
What does Basic Fibroblast Growth Factor (bFGF) do?
Causes cell division of endothelial cells
May increase NO production
Vasodilation
Supports angiogenesis
Exercise collateralisation in muscle
Cell damage or stretch in angiogenesis
Helps recruit perivascular cells to growing vessels to aid maturation, regulate extracellular matrix
Works with VEGF
Endothelial cell proliferation
Increases collateral perfusion in myocardium and myocardial function
Important in communication between endothelial cells and extracellular matrix
Endothelial cell migration
Apoptosis
Mediates attachment between cell and it’s surroundings - signalling to cell from matrix
