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Flashcards in Eicosanoids Deck (13):
1

Enzyme that catalyzes the formation of histamine

Histidine-decarboxylase catalyzes the formation of histamine from L-histidine

2

Where is histamine-decarboxylase located

• Mast cells, basophils, cells of the epidermis, cells in the gastric mucosa, neurons, cells of rapidly growing tissues (especially certain tumors)

3

H1 receptor acts via

Gq: increases IP3 and DAG

4

H2 receptor acts via

Gs: increases cAMP

5

H3 receptor acts via

Gi: decreases cAMP

6

H4 receptor acts via

Gi: decreases cAMP

7

H1 receptor is predominantly found in _______ where it ____

1. blood vessels
2.
➢ vasodilation: decreases BP (via NO release)
➢ Bronchoconstriction (features of anaphylaxis)

8

H2 receptor is predominantly found in _______ where it ____

stomach
2. stimulates gastric secretion

9

H3 receptor is predominantly found in _______

presynaptic: brain, myenteric plexus, other neurons

10

H4 receptor is predominantly found in _______

Eosinophils. neutrophils, CD4 T-cells

11

Histamine Release Inhibitors

• Beta2-adrenoceptor agonists
• Theophylline
• Cromolyn sodium and nedocromil
• Glucocorticoids (IgE-dependent release)

12

physiologic antagonists

Epinephrine (hence used in anaphylactic shock)

13

Receptor antagonists

• H1 receptor antagonists (antihistamines)
• H2 receptor antagonists