Memorial University DAI: The effect of chemical denervation on the action of acetylcholine and substance P in the isolated perfused mesenteric arterial bed of the rat

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Title	The effect of chemical denervation on the action of acetylcholine and substance P in the isolated perfused mesenteric arterial bed of the rat
Author	Miller, Margaret
Description	Thesis (M.Sc.)--Memorial University of Newfoundland, 1990. Medicine
Date	1989
Pagination	vii, 137 leaves : ill.
Subject	Acetylcholine; Substance P; Mesenteric artery
Subject.MESH	Acetylcholine; Substance P; Mesenteric Arteries
Degree	M.Sc.
Degree Grantor	Memorial University of Newfoundland. Faculty of Medicine
Discipline	Medicine
Language	Eng
Notes	Bibliography: leaves 109-137.
Abstract	Vascular endothelial cells respond to certain vasoactive agents by releasing factors which act on medial smooth muscle to cause relaxation or contraction of blood vessels. One of the substances responsible for endothelium-dependent relaxation to acetylcholine has recently been identified as nitric oxide. We have tested the hypothesis that the ability of vascular endothelium to cause relaxation in response to stimulation by vasoactive agents is related in some way to the pattern of perivascular innervation. The actions of acetylcholine and substance P were tested in the presence of methoxamine induced tone in the isolated perfused mesenteric arterial bed of the rat. Tissues were tested from untreated normal 12 week old Sprague-Dawley rats and from rats which had been treated from birth with capsaicin to prevent the development of peptidergic perivascular innervation or 6-hydroxydopamine to prevent development of catecholaminergic innervation. Concentration dependent endothelium-dependent relaxations were observed in response to acetylcholine. The concentration response curve to acetylcholine was shifted 1.2 log units to the right in the capsaicin-treated group but no change was observed with 6-hydroxydopamine treatment. Substance P caused a dose dependent potentiation of the methoxamine induced tone which was not dependent on the presence of an intact endothelium. Relaxations to substance P were not observed at any dose. Sympathectomy with neonatal 6-OHDA treatment resulted in an increase in the substance P pressor response, but no changes were observed with capsaicin treatment. Thus, it appears that altering the peptidergic perivascular innervations results in a decreased sensitivity of the mesenteric arterial bed to acetylcholine and changes in the catecholaminergic fibre plexus result in an enhancement of the substance P modulation of adrenergic vasoconstriction.
Type	Text
Resource Type	Electronic thesis or dissertation
Format	Image/jpeg; Application/pdf
Source	Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries
Local Identifier	76058013
Rights	The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
Collection	Electronic Theses and Dissertations
Scanning Status	Completed
PDF File	(17.18 MB) -- http://collections.mun.ca/PDFs/theses/Miller_MargaretRN.pdf
CONTENTdm file name	197292.cpd