Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P20366 (substance P)
 21,176 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have explored in man the hypothesis that histamine released from dermal mast cells by neurotransmitters from afferent nerves contributes to vasodilatation of the axon reflex. The ability of substance P to release histamine from human skin in vivo, and the effects of a histamine H1-receptor antagonist on capsaicin-induced axon reflex flares were studied. Intradermal injections of substance P (50 pmol) produced a weal and flare response which was associated with increased histamine concentration in blood draining the site (mean plasma histamine concentration before injection 0.17 +/- 0.02 ng ml-1 (+/- s.e.mean), concentration one minute after injection 1.26 +/- 0.28 ng ml-1, n = 6). Terfenadine, an H1-receptor antagonist, had no effect on the flare response to intradermal injection of capsaicin at a dose which inhibited by more than 60% the flare response to exogenous histamine and to histamine released from dermal mast cells by substance P. Substance P releases histamine from human skin in vivo. However, whatever the nature of the neurotransmitter released from afferent nerves during the axon reflex, it does not produce vasodilatation through release of histamine from dermal mast cells. Histamine may still contribute to the flare by initiation of the reflex.
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PMID:Histamine is released from skin by substance P but does not act as the final vasodilator in the axon reflex. 242 44

Changes in pulmonary endothelial permeability and in microvascular hemodynamics in response to cumulative concentrations of acetylcholine (ACh) (10(-8) M to 10(-5) M) were investigated in isolated, perfused rabbit lungs. The total pressure gradient was partitioned into four components: arterial, pre- and postcapillary and venous. The capillary filtration coefficient (Kf, c) also was evaluated. ACh caused a significant increase in arterial and precapillary pressures at concentrations higher than 3 x 10(-6) M. The total pressure gradient and precapillary were significantly increased whereas arterial, postcapillary and venous pressure gradient remained unchanged. In papaverine (3 x 10(-4) M)-pretreated lungs, the vasoconstriction was abolished and a concentration-dependent increase in Kf,c was recorded from 10(-8) to 10(-5) M ACh. This reaction was accompanied by pulmonary edema. Atropine, indomethacin, aspirin, ketanserin, clonidine, morphine and (+/-)-CP 96-345, an antagonist of neurokinin NK1 receptors, completely prevented the effects of ACh on Kf,c. In contrast, cromolyn sodium and SR48968, a neurokinin NK2 antagonist, did not inhibit the response to ACh. Terfenadine together with cimetidine had a partially inhibitory effect. Changes in the Kf, c similar to those observed with ACh were induced by capsaicin (10(-4) M) by exogenous substance P (10(-7) M) and by 5-hydroxytryptamine (5-HT) (10(-4) M). The effects of SP were inhibited by aspirin, (+/-)-CP 96,345 and ketanserin, but not by atropine and antihistaminics. 5-HT effects were prevented by aspirin and not by (+/-)-CP 96,345. It was concluded that ACh-induced pulmonary edema was due to an increase in the capillary filtration coefficient.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Role of neuropeptides in acetylcholine-induced edema in isolated and perfused rabbit lungs. 768 2