TY  - JOUR
A1  - Jaiswal, Neelam
A1  - Lambrecht, Günter
A1  - Mutschler, Ernst
A1  - Tacke, Reinhold
A1  - Malik, Kafait U.
T1  - Pharmacological characterization of the vascular muscarinic receptors mediating relaxation and contraction in rabbit aorta
JF  - Journal of Pharmacology and Experimental Therapeutics
N2  - Studies were performed in the rabbit aortic rings, precontracted with norepinephrine, to determine the subtype(s) of muscarinic receptors involved in endothelium-dependent relaxation and contraction in the absence of endothelium elicited by cholinergic stimuli. Acetylcholine (ACh) and arecaidine propargyl ester (APE), a M2 and M3 agonist, produced a dose-dependent relaxation and contraction in endothelium-intact and endothelium-denuded rabbit aortic rings, respectively. Both of these responses were blocked by the muscarinic receptor antagonist atropine. M1 selective agonist McN-A-343 [4-[N-(3-chlorophenyl)carbamoyloxy]-2-butinyltrimethylammonium+ ++ chloride] did not produce any effect on the tone of precontracted aortic rings. ACh- and APE-induced relaxation in aortic rings with intact endothelium was selectively blocked by M3 receptor antagonists hexahydrosila-difenidol and p-fluoro-hexahydro-sila-difenidol (pA2 of 7.84 and 7.18) but not by M1 antagonist pirenzepine or M2 receptor antagonists AF-DX 116 [11-(2-[(diethylamino)methyl]- 1-piperidinyl]acetyl)-5, 11-dihydro-6H-pyrido-[2,3-b][1,4]-benzo-diazepin-6-one] and methoctramine. ACh- and APE-induced contraction was inhibited by M2 receptor antagonists AF-DX 116 and methoctramine (pA2 of 7.11 and 6.71) but not by pirenzepine, hexahydro-sila-difenidol or p-fluoro-hexahydro-sila-difenidol. ACh- and APE-induced relaxation or contraction were not altered by nicotinic receptor antagonist hexamethonium or cyclooxygenase inhibitor indomethacin. These data suggest that relaxation elicited by cholinergic stimulin in endothelium-intact aortic rings is mediated via release of endothelium-derived relaxing factor consequent to activation of M3 receptors located on endothelial cells, whereas the contraction in aortic rings denuded of their endothelium is mediated via stimulation of M2 receptors located on smooth muscle cells.
KW  - (4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium chloride/pharmacology
KW  - acetylcholine
KW  - animals
KW  - antihypertensive agents / pharmacology
KW  - aorta, abdominal / drug effects
KW  - aorta, abdominal / physiology
KW  - aorta, abdominal / ultrastructure
KW  - arecoline/analogs & derivatives
KW  - arecoline
KW  - atropine
KW  - diamines
KW  - endothelium, vascular / drug effects
KW  - endothelium, vascular / physiology
KW  - hexamethonium
KW  - hexamethonium compounds
KW  - indomethacin
KW  - male
KW  - muscarinic antagonists
KW  - muscle contraction
KW  - muscle relaxation
KW  - norepinephrine
KW  - parasympatholytics
KW  - piperidines
KW  - pirenzepine
KW  - rabbits
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-128358
VL  - 258
IS  - 3
ER  -