Watson inflamm sem 1 Flashcards
What symptoms of RA represent cycles of “acute” inflammation?
redness, swelling, chemical mediator release, neutrophil recruitment.
What type of mediator is histamine? [5]
- Pre-formed
- Rapidly produced
- Released from stimulated neurones.
- Produced following proteinase activation.
- Produced hours later.
Rapid inflammatory mediators produced from membrane lipids include [3]
- Eicosanoids (PGE2, PGI2)
- Leukotrienes (LTB4)
- PAF (platelet activation factor)
Stimulated neurons release these inflammatory mediators: [2]
- Substance P
2. Calcitonin Gene related peptide (CGRP)
Proteinase activation leads to the production of: [2]
Bradykinin
Complement factor C3a, C5a
iNOS, Cox-2 and cytokines are produced how soon after injury?
Hours later following protein synthesis.
Increased vascular permeability can come about because of: [5]
Histamine Eicosanoids, LTB4, LTC4 PAF Bradykinin C3a, C5a.
Histamine has what effect on vascular permeability?
Increases it.
Eicosanoids have what effect on vascular permeability?
Increase it.
Bradykinin has what effect on vascular permeability?
Increases it.
C3a + C5a have what effect on vascular permeability?
Increase it.
What mediators of inflammation are vasodilators? [5]
Histamine, Eicosanoids:PGE2, PGI2 Neuropeptides, SP, CGRP Bradykinin Nitric Oxide
Histamine has what effect on vasodilation?
Increases it.
PGE2 and PGI2 have what effect on vasodilation?
Increase it.
Substance P and CGRP (Neuropeptides) have what effect on vasodilation?
They increase it.
Which eicosanoids only cause vasodilation? (no effect on vascular permeability)
PGE2, PGI2.
LTB4 and LTC4 cause vascular permeability to increase.
What effect does nitric oxide release have on vasodilation?
Increases it.
Which inflammatory mediators cause both vasodilation and an increase in vascular permeability? [2]
Histamine
BRadykinin.
What is plasma exudation and what can cause it?
Plasma leakage: histamine and bradykinin act directly on endothelium to increase vasodilation and vascular permeability.
How do neutrophil activators increase plasma exudation?
Neutrophil-dependent mechanisms.
LTB4, FMLP, C5a, IL-8.
Why may inhibiting neutrophils be a more effective strategy in inflammatory disease management?
Some substances cause acute inflammation via actions on the endothelium only, histamine for example (and bradykinin). Others cause acute inflammation via actions on neutrophils: fMLP, LTB4, C5a, IL-8 etc.
Inhibiting or antagonising a single mediator is only effective in inflammation driven by that single substance e.g. H1 receptor-antagonists are only effective against the histamine component of the inflammatory/allergic response.
Which drug causes the production of histamine to halt and how is this done?
Tritoqualine (hypostamine). Inhibits histidine decarboxylase, preventing L-histidine being converted into histamine. The histamine that is already present is deactivated into imidazoyl acetic acid by histaminases.
Where is histamine mostly stored?
Mast cells, granular, large cells in the skin, lungs, gut, and nasal mucosa. Histamine is a basic drug.
What is the triple response?
A response to histamine or an allergen that is cutaneous.
- Arterial dilation (local reddening)
- Oedema formation (WHEAL)
- axon reflex (flare)-release of neutrophils.
What role does substance P play in the triple vascular response?
Cell damage stimulates sensory neurones –> send pain + itch signals to the CNS –> antidromic impulses also cause neuropeptide release from peripheral nerve branches.
SP + CGRP -> blood vessel dilation + SP stimulates histamine release from mast cells.
What is the pathophysical role of histamine? [2]
- Immediate hypersensitivity responses: allergic rhinitis, urticaria (skin rashes), anaphylactic shock.
- Hypersecretion of insulin results in excess acid production and formation of duodenal and peptic ulcers.
What is the role of the H1 receptor? [4]
- PLC linked so Ca2+ increase.
- Vasodilatory effects on arterioles via NO2
- Increased vascular permeability via endothelial contraction –> oedema
- Neuropeptide release.
GQ coupled.
What is the role of the H2 receptor? [4]
- AC leading to increased cAMP.
- Vasodilator, but limited significance in inflammation.
- Potent stimulator of gastric acid secretion.
- Vascular smooth muscle relaxation.
Gs coupled.
Which of the H receptors is Gq coupled?
H1:
1. PLC linked so Ca2+ increase.
2. Vasodilatory effects on arterioles via NO2
3. Increased vascular permeability via endothelial contraction –> oedema
4. Neuropeptide release.
GQ coupled.
What are the effects of stimulating the H1 receptor? [4]
- PLC linked so Ca2+ increase.
- Vasodilatory effects on arterioles via NO2
- Increased vascular permeability via endothelial contraction –> oedema
- Neuropeptide release.
What is the H4 receptor involved in?
Chemotaxis.
What do Chlorpheniramine, Astemizole and Loratidine have in common?
All antihistamines targeted for the H1 receptor. Newer: Astemizole and Loratidine.
Which H receptor is Gs coupled?
H2:
1. AC leading to increased cAMP.
2. Vasodilator, but limited significance in inflammation.
3. Potent stimulator of gastric acid secretion.
4. Vascular smooth muscle relaxation.
Gs coupled.
What is the difference between Astemizole, Loratidine and Chlorpheniramine?
Astemizole and Loratidine are newer H1 receptor antihistamines with lower lipophilicity.
What are some H2 receptor antagonists? What are their actions?
Cimetidine + newer —> Ranitidine
Inhibit p450 enzymes and can interact with other drugs.
Block gastric acid release from parietal cells.
What is arachidonic acid?
An essential fatty acid derived from red meat or via desaturation of lindeic acid.
Found in all cells of the body, primarily as a component of membrane phospholipids.
How is prostacyclin formed from phospholipids?
PPL –PLA2—> Arachidonate —-Cyclooxygenase—> Prostaglandin H2——Prostacyclin synthase—> Prostacyclin