Endothelial Function

Question 1

What are the functions of endothelium?

Answer 1

Capillary transport, regulation of plasma lipids, control of hemostasis, white blood cell adhesion, and modulaton of vascular smooth muscle reactivity

Question 2

What vasoactive substances are secreted by the endothelium?

Answer 2

Prostacyclin (vasodilation), endothelin (vasoconstrictor), nitric oxide (vasodilation), endothelial derived hyperpolarizing factor (vasodilation)

Question 3

What endothelial enzyme degrades norepinephrine and other catecholamines, serotonin?

Answer 3

Monoamine oxidase

Question 4

What structures allow for ion transfer between individual endothelial cells?

Answer 4

Myoepithelial Gap Junction

Question 5

How does prostaglandin I2 mediate vasodilation?

Answer 5

Increases cAMP, activating PKA, which phosphorylates MLCK and decreases activity

Question 6

What converts angiotensin I to angiotensin II?

Answer 6

Angiotensin converting enzyme (ACE)

Question 7

What is the effect of Angiotensin II?

Answer 7

Vasoconstriction

Question 8

When the endothelium is intact what platelet products cause vasodilation?

Answer 8

Vasopressin, ATP, ADP

Question 9

What is the physiologic response to a severed capillary?

Answer 9

Platelet aggregation and vasoconstriction

Question 10

What vasoconstrictive compound is produced by platelets?

Answer 10

Thromboxane

Question 11

On what cells does Thrombin act? What is its effects?

Answer 11

Endothelial cells; vasodilation

Question 12

How does the parasympathetic nervous system mediate vasodilation?

Answer 12

Acetylcholine binds to a muscarinic receptor on the endothelial cell, increasing calcium concentration which activates endothelial nitric oxide synthase, which converts L-arginine to nitric oxide. NO diffuses out to blood to inhibit platelet aggregation and out of the cendothelial cell to VSM and activates guanylyl cyclase, increasing cGMP, activating Protein kinase G and decreasing Ca++ and vasodilating

Question 13

What are the variants of nitric oxide synthase?

Answer 13

neuronal (nNOS), endothelial (eNOs), and inducible (iNOS)

Question 14

Which nitric oxide synthase variants require calcium?

Answer 14

eNOS

Question 15

When is iNOS produced?

Answer 15

Severe infection

Question 16

What is the effect of COX on vascular radius?

Answer 16

Vasodilative

Question 17

True or False: cAMP and cGMP both elicit vasodilation of vascular smooth muscle

Answer 17

True

Question 18

How does endothelial-derived hyperpolarizing factor mediate vasodilation?

Answer 18

It hyperpolarizes the membrane potential, causing it to be more negative and keeping v-gated calcium channels closed

Question 19

What are the effects of epinephrine on vascular smooth muscle?

Answer 19

Epinephrine binds to beta-2 receptors, activating adenylyl cyclase and increasing cAMP

Question 20

How does the Sympathetic nervous system mediate vasoconstriction?

Answer 20

NE binds alpha-receptors on VSM, activating PLC, increasing IP3, increasing Ca++

Question 21

How does endothelin mediate vasoconstriction?

Answer 21

Activates PLC, increasing IP3, increasing Ca

Question 22

What seems to the basis of hypertension?

Answer 22

Insufficient response to ACh because of damaged endothelium

Question 23

What vessels are usually used for bypass surgeries? Which maintains patency better?

Answer 23

Saphenous vein or internal mammary artery; Internal mammary artery