PHYS Vascular Endothelium

Question 1

Effect of ACh on blood vessel endothelium

Answer 1

ACh acts on M receptors -> release of endothelium-derived relaxing factor (EDRF) -> vascular smooth muscle relaxation.
In the case of endothelial cell damage: ACh acts on the M receptors of vascular smooth muscles -> vascular smooth muscle contraction.

Question 2

NO synthesis within endothelium

Answer 2

ACh/substance P act on receptors -> increase Ca2+ within endothelium -> synthesis of endothelium NO synthase.
NO synthesis converts L-arginine -> L-citrulline. NO is the by-product of this conversion reaction.

Question 3

Constitutive NO synthase vs Inducible NOS

Answer 3

Ca2+ dependent
Short bursts of release
Present in endothelium & nerves

Ca2+ independent
Longer term release
Present in immune cells

Question 4

Classify as NO as a EDCF/RF

Answer 4

RF

Question 5

Classify PGI2 as a EDCF/RF

Answer 5

RF – predominantly for larger vessels with lower resistance

Question 6

Classify EDHF as a EDCF/RF

Answer 6

(Endothelium Derived Hyperpolarising Factor). RF - predominantly for smaller vessels with higher resistance

Question 7

Classify angiotensin-II as a EDCF/RF

Answer 7

CF

Question 8

Classify ECE as an ECDF/RF

Answer 8

CF - Endothelium Converting Enzyme (ECE)

Question 9

Classify TxA2 as an EDCF/RF

Answer 9

CF - Thromboxane A2 (TxA2)

Question 10

Classify PGH2 as an EDCF/RF

Answer 10

CF

Question 11

Classify endothelin as an EDCF/RF

Answer 11

CF - may potentiate function of other contracting factors (EL-1, EL-2, EL-3).

Question 12

What is the affect of endothelium derived hyperpolarising factors vs hypopolarising factors on blood vessels?

Answer 12

Endothelium derived hyperpolarising factors causes hyperpolarisation of smooth muscle cells
therefore causing dilation. Opposite.

Question 13

Effect of NO on smooth muscle cell proliferation.

Answer 13

Decreases.