tolterodine-tartrate and 4-diphenylacetoxy-1-1-dimethylpiperidinium

To investigate the effects of tissue stretch and muscarinic receptor stimulation on the spontaneous activity of the urothelium/lamina propria and identify the specific receptor subtype mediating these responses.. Isolated strips of porcine urothelium with lamina propria were set up for in vitro recording of contractile activity. Muscarinic receptor subtype-selective antagonists were used to identify the receptors influencing the contractile rate responses to stretch and stimulation with carbachol.. Isolated strips of urothelium with lamina propria developed spontaneous contractions (3.7 cycles/min) that were unaffected by tetrodotoxin, Nω-nitro-L-arginine, or indomethacin. Carbachol (1 μM) increased the spontaneous contractile rate of these tissue strips by 122% ± 27% (P < .001). These responses were significantly depressed in the presence of the M3-selective muscarinic antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (10-30 nM) but were not affected by the M1-selective antagonist pirenzepine (30-100 nM) or the M2-selective antagonist methoctramine (0.1-1 μM). Stretching of the tissue also caused an increase in the spontaneous contractile rate, and these responses were abolished by atropine (1 μM) and low concentrations of 4-diphenylacetoxy-N-methylpiperidine methiodide (10 nM). Darifenacin, oxybutynin, tolterodine, and solifenacin (1 μM) all significantly depressed the frequency responses to carbachol (1 μM).. The urothelium with the lamina propria exhibits a spontaneous contractile activity that is increased during stretch. The mechanism appears to involve endogenous acetylcholine release acting on M3 muscarinic receptors. Anticholinergic drugs used clinically depress the responses of these tissues, and this mechanism might represent an additional site of action for these drugs in the treatment of bladder overactivity.

Topics: Animals; Atropine; Benzhydryl Compounds; Benzofurans; Carbachol; Cresols; Diamines; Mandelic Acids; Mucous Membrane; Muscarinic Antagonists; Muscle Contraction; Phenylpropanolamine; Piperidines; Pirenzepine; Pyrrolidines; Quinuclidines; Receptor, Muscarinic M3; Solifenacin Succinate; Stress, Mechanical; Swine; Tetrahydroisoquinolines; Tolterodine Tartrate; Urinary Bladder; Urothelium

1. Muscarinic cholinoceptors (MChR) in freshly dispersed rat salivary gland (RSG) cells were characterized using microphysiometry to measure changes in acidification rates. Several non-selective and selective muscarinic antagonists were used to elucidate the nature of the subtypes mediating the response to carbachol. 2. The effects of carbachol (pEC(50) = 5.74 +/- 0.02 s.e.mean; n = 53) were highly reproducible and most antagonists acted in a surmountable, reversible fashion. The following antagonist rank order, with apparent affinity constants in parentheses, was noted: 4-DAMP (8.9)= atropine (8.9) > tolterodine (8.5) > oxybutynin (7.9) > S-secoverine (7.2) > pirenzepine (6.9) > himbacine (6.8) > AQ-RA 741 (6.6) > methoctramine (5.9). 3. These studies validate the use of primary isolated RSG cells in microphysiometry for pharmacological analysis. These data are consistent with, and extend, previous studies using alternative functional methods, which reported a lack of differential receptor pharmacology between bladder and salivary gland tissue. 4. The antagonist affinity profile significantly correlated with the profile at human recombinant muscarinic M(3) and M(5) receptors. Given a lack of antagonists that discriminate between M(3) and M(5), definitive conclusion of which subtype(s) is present within RSG cells cannot be determined.

Topics: Alkaloids; Animals; Atropine; Benzhydryl Compounds; Benzodiazepinones; Binding, Competitive; Biosensing Techniques; Carbachol; Cholinergic Agonists; Cresols; Diamines; Dose-Response Relationship, Drug; Furans; Male; Mandelic Acids; Muscarinic Antagonists; Naphthalenes; Phenethylamines; Phenylpropanolamine; Piperidines; Pirenzepine; Rats; Rats, Sprague-Dawley; Receptors, Muscarinic; Submandibular Gland; Tolterodine Tartrate