TY - JOUR
T1 - Effects of muscarinic agents on cultured human trabecular meshwork cells
AU - Shade, Debra L.
AU - Clark, Abbot F.
AU - Pang, Iok Hou
N1 - Funding Information:
This study received financial support from Alcon Laboratories, Inc.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1996/3
Y1 - 1996/3
N2 - Intracellular calcium measurements were performed in cultured human trabecular meshwork cells preloaded with the cell permeant dye fura 2-AM. Fluctuations in calcium levels were then monitored with microscope-based ratio fluorometry. Carbachol increased intracellular calcium in a dose-dependent manner; as did oxotremorine-M, aceclidine, and pilocarpine. Carbachol's effect was blocked by the nonselective muscarinic antagonist atropine, as well as by muscarinic receptor subtype-selective antagonists such as pirenzepine (M1-selective), p-fHHSiD (M3-selective), and 4-DAMP (M1, M3 subtypes). Rank order of potencies for the antagonists' effects was atropine = 4-DAMP > p-fHHSiD > pirenzepine, a profile suggesting that the M3 receptor subtype is essential in the carbachol effect. Phospholipase C activity was estimated via measurement of total production of inositol phosphates in cultured human trabecular meshwork cells pre-exposed to 3H-myoinositol. In these cells, carbachol also stimulated phosphoinositide production in a dose-dependent manner, and an antagonist profile similar to that seen for calcium response was obtained when carbachol was used as the effector. The data indicate that muscarinic effects on cultured human trabecular meshwork calcium mobilization and phospholipase C activity are mediated by an M3-like receptor subtype. Therefore, the muscarinic M3 receptor may play a role in trabecular meshwork cell function(s).
AB - Intracellular calcium measurements were performed in cultured human trabecular meshwork cells preloaded with the cell permeant dye fura 2-AM. Fluctuations in calcium levels were then monitored with microscope-based ratio fluorometry. Carbachol increased intracellular calcium in a dose-dependent manner; as did oxotremorine-M, aceclidine, and pilocarpine. Carbachol's effect was blocked by the nonselective muscarinic antagonist atropine, as well as by muscarinic receptor subtype-selective antagonists such as pirenzepine (M1-selective), p-fHHSiD (M3-selective), and 4-DAMP (M1, M3 subtypes). Rank order of potencies for the antagonists' effects was atropine = 4-DAMP > p-fHHSiD > pirenzepine, a profile suggesting that the M3 receptor subtype is essential in the carbachol effect. Phospholipase C activity was estimated via measurement of total production of inositol phosphates in cultured human trabecular meshwork cells pre-exposed to 3H-myoinositol. In these cells, carbachol also stimulated phosphoinositide production in a dose-dependent manner, and an antagonist profile similar to that seen for calcium response was obtained when carbachol was used as the effector. The data indicate that muscarinic effects on cultured human trabecular meshwork calcium mobilization and phospholipase C activity are mediated by an M3-like receptor subtype. Therefore, the muscarinic M3 receptor may play a role in trabecular meshwork cell function(s).
KW - Human trabecular meshwork cells
KW - Intracellular calcium mobilization
KW - M receptors
KW - Muscarinic agents
KW - Phospholipase C
UR - http://www.scopus.com/inward/record.url?scp=0029918137&partnerID=8YFLogxK
U2 - 10.1006/exer.1996.0025
DO - 10.1006/exer.1996.0025
M3 - Article
C2 - 8690029
AN - SCOPUS:0029918137
SN - 0014-4835
VL - 62
SP - 201
EP - 210
JO - Experimental Eye Research
JF - Experimental Eye Research
IS - 3
ER -