Autacoids :( Flashcards
Histamine precursor and enzyme
Histidine
L-histidine decarboxylase
Histamine - stored in? Complexed with?
Mast cells and basophils
Complex with heparin-ATP in secretory granules (like suicide bombers)
Triple response of Lewis
Flush, wheal, flare
(Localized red spot) action and effect?
Flush
Relaxation of vascular smooth muscle
Vasodilation
(Swelling of edema) action and effect?
Wheal
Contraction of endothelial cells and post-capillary venule
Increased capillary permeability / leakage
(Brighter red halo) action and effect?
Flare
Local axon reflex
Indirect vasodilation
H1 distribution (2)
Smooth muscle endothelium, CNS
H1 rep antagonist (2)
Chlorphenamine, diphenhydramine
H2 distribution (4)
Parietal cells, cardiac muscle, mast cells, CNS
H2 rep antagonist (2)
Ranitidine (Zantac), cimetidine
Selective H2 blocker, acts on stomach
Ranitidine
H3 distribution
CNS: presynaptic, myenteric plexus, other neurons
H3 rep antagonist (3)
Thioperamide, cloben, burimamide
H4 distribution
Cells of hematopoietic origin (bone marrow)
H4 antagonist (2)
Thioperamide (JNJ7777120), zymosan
H receptors distributed widely in periphery and CNS
H1, H2
H1 activates _, -> _ pathway
H1 activates Gq/11 -> PLC-IP3-Ca pathway
H2 activates _, -> _ pathway
H2 activates Gs -> adenylyl cyclase-cAMP-PKA pathway
H3 and H4 activate _ -> inhibit
H3 and H4: Gi/o -> inhibit adenylyl cyclase
Betahistine used for?
anti-vertigo (*H3, H4)
H receptors involved in neurotransmission, inflammation, circadian rhythm, nausea (vomiting center), vertigo
H3, H4
H receptor confined largely to CNS
H3
H receptors for lab rat experiments
H3, H4
H1 blockers (5)
diphenhydramine (Benadryl) chlorphenamine hydroxyzine (urticaria) meclizine (Bonamine) promethazine (anesthesia; drug-drug -> arrythmia)
H1 blocker pharmacodynamics (4)
Blocks Type I hypersensitivity reaction
Incomplete block of vascular smooth muscle relaxation (H1 & H2 for complete suppression)
CNS: sedation, anti-emetic
Anti-cholinergic: dryness
Antihistamine actions not mediated by H-receptor, ex.
Anticholinergic, via muscarinic receptor
Scopolamine for anti-vertigo
Kinin
Precursors, catalyst
Precursors: HMW, LMW kininogen
Catalyst: Plasma and tissue kallikrein
Kinin metabolism inhibited by? Half life?
Kininase or converting enzyme
15 secs
Endogenous KKK systems supports which part of the clotting system
Intrinsic pathway