24 Endothelium

Question 1

List the 3 vasodilators/ EDRFs released by the endothelium.

Answer 1

1. Nitric oxide
2. Prostacyclin (PGI2)
3. Endothelium derived
   hyperpolarizing factor (EDHF)

Question 2

List the 5 contracting molecules/ vasoconstrictors released by the endothelium.

Answer 2

1. Superoxide ion
2. Prostaglandin F2a
3. Prostaglandin H2
4. Endothelin
5. Angiotensin II

Question 3

Vasodilators like acetylcholine, substance P and histamine causes an increase in Ca2+ in endothelial cells, which stimulates eNOS to convert _____ to _________. The product then enter vascular smooth muscles and convert ________ to _______ by ______. ______ increases, intracellular Ca2+ decreases, causing relaxation.

Answer 3

L-arginine
NO

GTP to cGMP by GC

PKG increases

Question 4

Other than NO, PGI2 is also a vasodilator. It binds to ____ coupled receptors and stimulates _________________________________.

Answer 4

Gs

ATP > cAMP increases by AC, PKA increases, intracellular Ca2+ decreases, relaxation occurs.

Question 5

In addition to NO and PGI2, ________ is also a vasodilator. It opens _______ channels and cause __________. At last, intracellular Ca2+ decreases.

Answer 5

Endothelium derived hyperpolarizing factor (EDHF)

K+
hyperpolarization

Question 6

_________ are inhibitors of eNOS and convert L-arginine to ____ and ______.

Answer 6

Arginase;

Urea + ornithine

(urea cycle!)

Question 7

What are the 3 stimulative functions of NO?

Answer 7

1. Vascular smooth muscle relaxation
2. Re-endothelization
3. Vascular smooth muscle apoptosis

Question 8

What are the 5 inhibitory functions of NO?

Answer 8

1. Platelet aggregation (thrombosis)
2. Monocyte invasion
3. Vascular smooth muscle proliferation
4. Matrix formation
5. Endothelial cell apoptosis

Question 9

What is NO's lifetime in the body?
A. 1s
B. 100s
C. 1 day
D. 1 week

Answer 9

A

Question 10

What can the plasma levels of nitrite and nitrate reflect?

Answer 10

ability of endothelium to produce and liberate NO

Question 11

______ is a NO donor for vasodilation upon occlusion.

Answer 11

Nitroglycerine

Question 12

NO stimulates GC to convert GTP to cGMP, and thus PKG. What 4 effects are achieved?

Answer 12

1. Stimulate Ca2+ ATPase to pump Ca2+ out of cell
2. Stimulate K+ to leave cell, which in turns reduces Ca2+ entry via Ca2+ voltage gated channels.
3. inhibit Ca2+ voltage gated channels for Ca2+ entry
4. Stimulate Ca2+ ATPase on sarcoplasmic reticulum to increase Ca2+ uptake

> decrease intracellular Ca2+

Question 13

Prostacyclin binds to Gs protein to stimulate AC to convert ATP to cAMP. PKA increases, what happens next?

Which vasodilator acts the same too?

Answer 13

Opening of K+ channels leads to hyperpolarization. This reduced the activity of voltage-gated Ca2+ channels and thus reduced intracellular Ca2+ > Vasorelaxation

EDHF

Question 14

What are the MAOs of Superoxide anion and endothelin, PGF2a and PGH2 in causing vasoconstriction?

Answer 14

Superanion anion destroys NO directly

Others: stimulate voltage gated Ca2+ channels for increasing Ca2+ uptake

Question 15

Endothelial dysfunction is caused by an imbalance between _____ and _____.

Answer 15

Too much ROS (reactive oxygen species)

decreased NO

Question 16

Which of the following is/are not risk factors of endothelial dysfunction?

A. Hypertension
B. Diabetes
C. Dyslipidemia
D. Sedentary lifestyle
E. Pregnancy
F. Menopause 
G. Excessive inflammation
H. Exercising 
F. Mental stress

Answer 16

H only

C: too much cholesterol

Question 17

What can be used to protect our vascular function? (3 things)

Answer 17

Polyphenols (chocolate and wine)
Antioxidants (tea)
Resveratrol (wine)