アブストラクト（22巻1号：The Bulletin of Kanagawa Dental College）

The Bulletin of Kanagawa Dental College

English

Title　： Endotoxin Increases Sensitivity of Prejunctional Muscarinic Receptors in Rabbit Mesenteric Artery
Subtitle　： ORIGINAL ARTICLES
Authors　： Tsukasa Sekishita, Eiichiro Okabe
Authors（kana）　：
Organization　： Department of Pharmacology, Kanagawa Dental College
Journal　： The Bulletin of Kanagawa Dental College
Volume　： 22
Number　： 1
Page　： 8-17
Year/Month　： 1994 / 3
Article　： Original article
Publisher　： Kanagawa Odontological Society
Abstract　： [Abstract] To assess the decreased responsiveness induced by E.coli lipopolysaccharide (LPS) of vasculature to electrical stimulation, the interaction between LPS treatment and prejunctional inhibitory muscarinic receptor sensitization was studied in the rabbit mesenteric artery. The experiments were performed on artery rings isolated 20 hr after intravenous treatment with LPS or saline as well as on artery rings isolated from non-treated rabbits. When neural elements in the artery rings (with endothelium) from the non-treated animals were stimulated electrically (10 V, 2 msec, 1 to 32 Hz), there was a phentolamine sensitive contraction ; even in endothelium-denuded vessel rings, contraction evoked by electrical stimulation (8 Hz, 5 min) was enhanced by atropine at concentrations which showed potent inhibitory effect on endothelium-dependent relaxation induced by acetylcholine (ACh). Furthermore, the contractile response to electrical stimulation was enhanced in the rings denuded of their endothelium, suggesting that electrical stimulation produces release of ACh as well as norepinephrine (NE) from perivascular nerves ; the released ACh activates both prejunctional inhibitory muscarinic receptors mediating the inhibition of NE release and postjunctional muscarinic receptors mediating the formation of endothelium-derived relaxing factor(s). Exogenously added ACh at concentrations which showed only slightly attenuation of electrically (16 Hz, 13 min) induced steady-state contraction in the endothelium-denuded rings prepared from saline-control animals strongly inhibited the contraction in rings from the LPS-treated animals ; the observed effect of ACh in LPS-treated ring preparations was effectively blunted by atropine. In these experiments, pirenzepine (a muscarinic M1-receptor antagonist) or gallamine (a muscarinic M2-receptor antagonist) had no preferential effect on the inhibition afforded by ACh. It is suggested that LPS increases sensitivity of prejunctional muscarinic receptors, possibly M3-receptors. Therefore, NE release may be inhibited in the rabbit mesenteric artery.
Practice　： Dentistry
Keywords　： Endotoxin, Prejunctional Muscarinic Receptors, Endothelium, Nerve Stimulation, Rabbit Mesenteric Artery