Test 2: lecture 22 autocoids 1 Flashcards
what are two amine derived autacoids
histamine
5-Hydroxytryptamine, aka Serotonin
what are two peptide derived autacoids
angiotensin
bradykinin
histamine is a major mediator for —
inflammation
anaphylaxis
gastric acid
arousal (awake)
where can you find histamine in the body
Major storage in specialized vesicles (granules):
* Mast cells (skin, bronchial and intestinal mucosa)
* Basophil granulocytes (blood)
* Enterochromaffin-like cells (stomach mucosa)
how to make histamine
histidine (L-histidine decarboxylase)→ histamine
— are antagonists of H1 receptor
pyrilamine
Benadryl (diphenhydramine)
Chlorphen… (Diathal)
Claratin, Zyrtec
histamine receptor found in smooth muscle, endothelial cells and CNS
— is a antagonist of H2 receptors
ranitidine (zantac)
cimetidine (tagamet)
will cause decreased gastric acid production
Histamine receptor found in gastric parietal cells, cardiac muscle, mast cells and CNS
— is an agonist of H1 receptor
2-methyl-histamine
histamine receptor found in smooth muscle, endothelial cells and CNS
— cells in the stomach mucosa can release histamine
Enterochromaffin-like cells
histamine can be released in response to —
- Tissue injury/trauma
- Physical agents: heat, cold, (heart burn from cold water), x-rays, etc.
- Chemical compounds: (e.g. morphine, tubocurarine
- Immunological: IgE → allergy and resistance to parasites).
histamine released from mast cells will cause what clinical signs
small red spots- local dilation of blood vessels
large red flare
wheal
histamine will — post capillary venules. Will — permeability of endothelium. mediates attraction of — cells and irriates nerve endings
dilate
increase- allows for edema/swelling
inflammatory cells ( neutrophils, eosinophils, basophiles, monocytes,
lymphocytes)
cause pain/itching
what antibody does histamine cause allergic reaction
IgE
what kind of allergic diseases does mast cells play a role in
asthma, eczema, allergic rhinitis, flea allergy dermatitis
anaphylaxis is a large release of histamine which causes
systemic vasodilation → shock
which histamine receptor deals with pain and itching
H1
which histamine receptor for sleep-wake cycle
H1 and/or H3
promotes wakefulness
presynaptic H3 receptors will reduce release of — in the brain and peripheral nerves
aCh, amines, peptides
histamine effects on cardiovascular system
will cause vasodilation of aterioles and NO release (which also causes vasodilation) → ↓BP
heart will compinsate by ↑HR
Flushing, sense of warmth, headache (vasodilation)
Urticaria (hives)
what will histamine do in the lungs
what is the exception?
humans and GP: cause bronchostriction (H1)
histamine is toxic to GP
rabbits and other species: bronchodilation (H2>H1)
histamine will do what to the smooth muscle of the GI tract
Guinea pigs/Human: contraction of intestinal smooth muscle- H1
Contraction of guinea pig ileum standard bioassay for histamine.
histamine will do what to smooth muscle of uterus
some species are sensitive and histamine can induce contractions→ abortion
which histamine receptor causes activation of gastric parietal(oxyntic) cells to realease gastric acid
H2
will cause increases production of pepsin, and intrinsic factor
can block with H2 but not H1 antihistamine drugs
H3 agonist will — acid secretion stimulated by food
inhibit
fish poinsoning/ bacterial histamine production will causes
- Flushing
- Hypotension
- Tachycardia
- Headache
- Wheals / hives / urticaria
- Bronchoconstriction
- Gastrointestinal upset
Histamine should not be given to asthmatics, patients with active ulcer disease or gastrointestinal bleeding
— is a physiologic antagnoist to histamine and will cause rapid bronchodilation
epinephrine (EpiPen)
acts on different receptors then H1 which cause constriction
— and — will inhibit release of histamine
Cromoglicate, nedocromil: asthma treatment (Human).
Beta 2 adrenoreceptor agonists also reduce histamine release
side effects of 1st gen H1 receptor antagonists
drowsiness
dry mucous membranes
decreased GI motility
inhibits muscarinic cholinoreceptor, serotonin, local anaesthetic receptors
1st gen:
* Ethanolamines: e.g. diphenhydramine (Benadryl®)
* Alkylamines: Chlorpheniramine Maleate (diathal)
* Ethylaminediamines: e.g. pyrilamine (Histall®; H)
— is often used in small animal practice as H1 receptor antagonist; also acts as serotonin/epinephrine reuptake inhibitor (SNRI), so has mild antidepressant properties
Chlorpheniramine (diathal)
has less sedating effect then other 1st gen H1 anatgonists (benadryl)
what are some second gen H1 receptor antagonists?
Cetirizine (Zyrtec®)
Loratadine (Claritin®)
why are 2nd gen H1 receptor antagonists less sedative
less lipid soluble, can’t get into CNS as easily
Loratadine (Claritin®), Cetirizine (Zyrtec®)
H1 receptor antagonists DO NOT block gastric secretion, these are contolled by —
H2 receptors
H1 receptor antagonists will prevent — in the lungs
bronchochonstriction
should use EPI in emergency, then H1 anathonist
some — gen H1 antagonist drugs can help with motion sickness / vestibular disturbances / anti-nausea /
1st
what are some H2 antagonists
cimetidine (Tagamet®, prototype)
ranitidine
Famotidine
Pepcid complete
nizatidine
H2 blockers can be used to treat
decrease release of gastric acid
- duodenal ulcers
- uremic gastritis, stress-related erosive gastritis, esophagitis
- duodenal gastric reflux →prokinetic effects promoting gastric emptying, GI motility
