Pharmacology

Question 1

What are prostaglandins?

Answer 1

Lipid compounds derived from fatty acids. Examples include PGE1 and PGE2. Roles include vasodilation or vasoconstriction and preventing/causing aggregation of platelets during inflammation.

Question 2

Metabolism of Arachidonic acid

Answer 2

By Constitutive COX-1 physiologic prostaglandins
By COX-2 which is induced for inflammatory purposes
By Lipoxygenase for use by Mast cells and Eosinophils

Question 3

Pathway of Prostaglandin formation

Answer 3

From Cell membrane with phospholipids attached to glycerol backbone Arachidonic Acid is formed by Phospholipase A cleavage. Arachidonic is metabolised by Cyclooxygenase to form unstable Endoperoxides which undergo isomerisation to form Prostaglandins - PGE2, PGF2 PGD2

Question 4

Name some stable Prostaglandins, well name them all hehe

Answer 4

PGE2 - Vasodilator and relaxes smooth muscles. Decreases BP, Produces fever and increases pain sensitivity
PGF2alpha/PGD2- Bronchoconstrictor

Act locally degraded locally

Question 5

Role of PGE2

Answer 5

promote GI blood flow, Angiogenesis, mucus secretion, reduce gastric acid secretion.
Released by cytokine activated macrophages and causes releases of cAMP in the hypothalamus which causes fever
Works in conjunction with Bradykinin which makes vasculature more leaky and enhances PGE2 production. This increases pain

Question 6

Prostacyclin and Thromboxane A2 are forms of prostaglandins. List their functions

Answer 6

PGI2 and TXA2
Prostacyclin- produced by endothelial cells reduces platelet activation and is a vasodilator
Thromboxane A2 counteracts the effects of prostacyclin and causes vasoconstriction and platelet activation

Question 7

Role of Aspirin

Answer 7

Higher in GI tract and lower in circulation. Enough balance to cause irreversible acetylation of COX in some platelets(in GI). This reduces Thromboxane production but Prostacyclin production not affected as it is produced by endothelium.

Also produces Lipoxins and enhances inflammation

Question 8

5-Lipoxygenase

Answer 8

Derived from Arachidonic Acid LTA4
Distributed in inflammatory cells - activated by increase in intracellular calcium - allergy
LTE/LTD - like chemokines
LTA4 is a bronchoconstrictor - leaky vessels and causes oedema
Leukotriene B4 attracts leukocytes

Question 9

Anti-Histamine

Answer 9

Released from Mast cells on mucosal surfaces and Basophils in blood.
Causes vasodilation and increased vascular
H1 antagonist - hay fever
H2 treats peptic ulcers

Question 10

Bradykinin

Answer 10

Peptide mediator in pain and inflammation 
Factor XIII cleavage by angiotensin
Dilates arterioles and venules
Vascular permeability
Stimulates nerves pain