L6. Autacoids Flashcards
2 main categories of autacoids
histamine
eicosanoids
4 categories of eicosanoids
- prostanoids
- leukotrienes
- 12-HETE
- lipoxins
3 types of prostanoids
- Prostacyclins PGI2
- prostaglandins
- Thromboxane TXA2
3 types of prostaglandins
PGD2
PGF2a
PGE2
describe syntheiss of histamine
precursor L-histidine via L-histidine decarboxylase
which 2 cells store histamine
mast cells
basophils
2 times when histamine is release
- inflammation/allergic reaction
2. drugs
name 4 drugs which cause histamine release
- morphine
- radiocontrast media
- tubocurarine
- vancomycin
how does histamine release affect Ca2+?
increases cytosolic Ca2+
4 main histamine receptor
H1-H4
location of H1 receptor
smooth muscle
4 effect of histamine on H1 receptor
- vasodilation
- increased vascular perm
- contraction of smooth muscle
- itch and pain due to stimulation in nerve endings
2 location of H2 receptor
gastric parietal cells, heart
location of H3 receptor
presynaptic terminals
what is the triple response to histamine
- red spot
- brighter red flush/ flare
- wheal
what is the red spot caused by?
direct vasodilator effect
what is the flare caused by?
indirect vasodilation
what is the wheal caused by?
increased capillary permeability
2 pathophysiological roles of histamine
- type 1 hypersensitivity reactions
2. gastric acid secretion from gastric paritel cells
which receptor does histamine act on to produce hypersensitivity reaction
H1
which receptor does histamine act on to produce gastric acid secretion
H2
what 2 conditions are antihistamines only useful in treating
hayfever, urticaria
2 pathological conditions caused by excessive gastric acid secretion
- GORD - gastro-oesophageal reflux disease
2. peptic ulcers
2 examples of H1 receptor antagonists - which have a sedative effect
promethazine, chlorpheniramine
3 examples of H1 receptor antagonists - which dont have a sedative effect
cetrizine
fexofenadine
terfenadine
3 examples of H2 receptor antagonists
- cimetidine
- ranitidine
- famotidine