Nitric oxide

Question 1

What is nitric oxide?

Answer 1

UBIQUITOUS mediator

Question 2

What is NO connected to?

Answer 2

Blood vessel control, immune response and neurotransmission

Question 3

What are the forms of NOS?

Answer 3

Inducible form (iNOS) and constitutive forms (eNOS and nNOS)

Question 4

What is NOS?

Answer 4

Nitric oxide synthase

Question 5

Which forms of NOS are calcium dependant?

Answer 5

Constitutive

Question 6

What expresses the iNOS?

Answer 6

Macrophage, neutrophil, fibroblast, vascular smooth muscle and endothelial cell

Question 7

What activates iNOS?

Answer 7

Bacterial lipopolysaccharides and or cytokines

Question 8

What is the biosynthesis of NO?

Answer 8

L-arginine+oxygen > L-citrullin + nitric oxide

Question 9

Where is L-Arginine present?

Answer 9

Endothelial cell cytoplasm

Question 10

How and why is arginine transported?

Answer 10

It has a positive charge and so is transported by cationic amino acid transporters (CAT)

Question 11

What is the most important CAT?

Answer 11

Y+

Question 12

What type of gas is NO?

Answer 12

Lipophilic

Question 13

How does NO cause relaxation?

Answer 13

Increasing the cGMP

Question 14

How does it increase cGMP?

Answer 14

by activating the guanylyl cyclase

Question 15

What is the tunica interna?

Answer 15

endothelial cells in blood vessel

Question 16

What is the tunica media?

Answer 16

smooth muscle cells in blood vessel

Question 17

Tunica externa

Answer 17

connective tissue in blood vessel

Question 18

What effect does NO have on blood vessels?

Answer 18

Vasodilation

Question 19

Which receptor does ACh act on?

Answer 19

M3

Question 20

What pathway does this activate?

Answer 20

IP3 production

Question 21

What does IP3 do?

Answer 21

Binds with IP3 receptors on internal Ca2+ store causing calcium increase

Question 22

Angina pectoris

Answer 22

arteries supplying blood to heart muscles are narrowed

Question 23

What is treatment of angina pectoris?

Answer 23

cause vasodilation by activating NO using glyceryl trinitrate or amyl nitrite

Question 24

NOs most famous role?

Answer 24

treating erectile dysfunction - sildenafil

Question 25

How does viagra work?

Answer 25

It inhibits the PDE which would usually break down the cGMP

Question 26

What does NO bind in mitochondria?

Answer 26

It binds to the Fe in iron sulphur clusters causing necrotic cell death

Question 27

What can NO cause?

Answer 27

Oxidative damage

Question 28

What does NO do in the brain?

Answer 28

- Retrograde signalling neurotransmitter - Enhances transmitter release from the Schaffer collateral terminals in hippocampal CA1 region - Contributes to LTP formation - Role in spatial memory

Question 29

What happens to NO when oxidated?

Answer 29

Inactivated