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20 Cards in this Set
- Front
- Back
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Histidine decarboxylase |
Converts histidine into histamine |
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Histaminase (diamine oxidase) |
Breaks down histamine into N-methylhistamine |
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Histamine release also caused by... |
Complement components C3a and C5b Substance P Morphine, tubocurarine |
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Histamine release inhibited by... |
Beta adrenoceptor agonists |
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H1 receptor coupling |
Gq
PIP2, PLC, IP3, DAG, stimulate calcium release |
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H1 receptor effects |
Vasodilation Bronchoconstriction Itching Increased vascular permeability |
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Promethazone |
1st generation H1 receptor antagonist
Allergies Nausea and vomiting Insomnia |
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Diphenhydramine |
1st generation H1 receptor antagonist
Coughing and nausea Sedative |
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Fexofendine |
2nd generation H1 receptor antagonist
Allergies |
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Cetirizine |
2nd generation H1 receptor antagonist
Hay fever Allergies Hives (urticaria) |
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Loritadine |
2nd generation H1 receptor antagonist
Allergies |
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Cinnarizine |
2nd generation H1 receptor antagonist
Motion sickness Vertigo |
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H2 receptor coupling |
Gs
Increased cAMP and PKA activation |
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H2 receptor effects |
Stimulate gastric acid secretion Relax smooth muscle Speed up HR |
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Cimetidine |
H2 receptor antagonist
Heartburn Peptic ulcers |
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Ranitidine |
H2 receptor antagonist
Peptic ulcers GERD Hives |
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H3 and H4 receptor coupling |
Gi
Decreased cAMP and PKA stimulation |
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H3 receptor effects |
Autoreceptor, negative feedback. Inhibits synthesis of histamine |
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H4 receptor effects |
Decrease histamine production in bone marrow and mast cells |
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Drug treatment of anaphylaxis |
Immediate: adrenaline Other drugs: H1 receptor antagonist, glucocorticoids |
