TY - JOUR
T1 - Activation of cholinergic receptors blocks non-adrenergic non-cholinergic contractions in the rat urinary bladder
AU - Lai, H. Henry
AU - Smith, Christopher P.
AU - Munoz, Alvaro
AU - Boone, Timothy B.
AU - Szigeti, Gyula P.
AU - Somogyi, George T.
N1 - Funding Information:
This work was supported by the National Institute of Health (R01-DK-069988) and the American Urological Association Foundation.
PY - 2008/12/16
Y1 - 2008/12/16
N2 - In the present study, the plasticity of the non-adrenergic non-cholinergic (NANC) response was investigated. Isolated rat bladder strips were electrically stimulated and the evoked contractions were isometrically recorded. The NANC part of the contractions were unmasked by applying 500 nM 4-DAMP, a potent muscarinic antagonist. Treatment of the bladder strips with 10 μM carbachol (a cholinergic agonist) increased the muscle tone but did not alter the neurally evoked contractions. However, carbachol decreased: (1) the NANC response from 74.6% to 33.3% of control and (2) the purinergic contractile response to α,β-methylene ATP (α,β-mATP) (10 μM) from 97.0% to 43.4% (p < 0.05). Treatment with the cholinesterase inhibitor eserine (10 μM) also significantly decreased the NANC response to 21.1% (p < 0.0001). The purinergic receptor antagonist suramin (100 μM) did not affect the neurally evoked contractions, however; subsequent addition of 4-DAMP decreased the contractions to 31%. Activation of the smooth muscle cholinergic receptors (with carbachol or eserine) and purinergic receptors (with α,β-mATP) decreased the NANC contractions and the direct contractile response to α,β-mATP. When the electrically evoked contractions were facilitated by the L-type Ca2+ channel activator, Bay-K 8644 the subsequent application of 4-DAMP did not unmask inhibited NANC contractions. We conclude that activation of muscarinic receptors by cholinergic agonist, carbachol or by endogenous acetylcholine (ACh) induce a cascade of events that leads to diminished purinergic response and consequently an inhibition of the bladder NANC response.
AB - In the present study, the plasticity of the non-adrenergic non-cholinergic (NANC) response was investigated. Isolated rat bladder strips were electrically stimulated and the evoked contractions were isometrically recorded. The NANC part of the contractions were unmasked by applying 500 nM 4-DAMP, a potent muscarinic antagonist. Treatment of the bladder strips with 10 μM carbachol (a cholinergic agonist) increased the muscle tone but did not alter the neurally evoked contractions. However, carbachol decreased: (1) the NANC response from 74.6% to 33.3% of control and (2) the purinergic contractile response to α,β-methylene ATP (α,β-mATP) (10 μM) from 97.0% to 43.4% (p < 0.05). Treatment with the cholinesterase inhibitor eserine (10 μM) also significantly decreased the NANC response to 21.1% (p < 0.0001). The purinergic receptor antagonist suramin (100 μM) did not affect the neurally evoked contractions, however; subsequent addition of 4-DAMP decreased the contractions to 31%. Activation of the smooth muscle cholinergic receptors (with carbachol or eserine) and purinergic receptors (with α,β-mATP) decreased the NANC contractions and the direct contractile response to α,β-mATP. When the electrically evoked contractions were facilitated by the L-type Ca2+ channel activator, Bay-K 8644 the subsequent application of 4-DAMP did not unmask inhibited NANC contractions. We conclude that activation of muscarinic receptors by cholinergic agonist, carbachol or by endogenous acetylcholine (ACh) induce a cascade of events that leads to diminished purinergic response and consequently an inhibition of the bladder NANC response.
KW - Bladder contractility
KW - Bladder smooth muscle
KW - Muscarinic acetylcholine receptors
KW - Nicotinic acetylcholine receptors
KW - Non-adrenergic
KW - Non-cholinergic (NANC) contractions
KW - P2X purinergic receptors
KW - Receptor interaction
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U2 - 10.1016/j.brainresbull.2008.07.011
DO - 10.1016/j.brainresbull.2008.07.011
M3 - Article
C2 - 18755252
AN - SCOPUS:56349155140
SN - 0361-9230
VL - 77
SP - 420
EP - 426
JO - Brain Research Bulletin
JF - Brain Research Bulletin
IS - 6
ER -