Functional muscarinic cholinoceptors in the isolated canine ureter
| Autor: | Nobuo Shibata, Makoto Murakami, Isao Wanajo, Masami Kojima, Yoshitaka Tomiyama, Yoshinobu Yamazaki |
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| Rok vydání: | 2002 |
| Předmět: |
Agonist
Male medicine.medical_specialty Contraction (grammar) Carbachol medicine.drug_class Cholinergic Agonists In Vitro Techniques Potassium Chloride chemistry.chemical_compound Dogs Internal medicine Muscarinic acetylcholine receptor Methoctramine medicine Animals Pharmacology Dose-Response Relationship Drug Muscle Smooth General Medicine Pirenzepine Receptors Muscarinic Atropine Endocrinology chemistry Himbacine Ureter medicine.drug Muscle Contraction |
| Zdroj: | Naunyn-Schmiedeberg's archives of pharmacology. 367(4) |
| ISSN: | 0028-1298 |
| Popis: | The purpose of present study was to characterize the functional muscarinic cholinoceptor (mAChR) subtypes in the isolated canine ureter. Carbachol (CCh), a non-selective mAChR agonist, concentration-dependently increased the frequency of the rhythmic contractions in isolated spiral ureteral preparations, the pD(2) value being 5.78+/-0.12. We then evaluated the effects of subtype-selective mAChR antagonists on the CCh-induced rhythmic contractions. The rank order of antagonistic potencies (apparent pA(2)) was 4-diphenylacetoxy- N-methylpiperidinemethiodide (4-DAMP; M3-subtype selective; 9.31+/-0.06)atropine (non-selective; 9.16+/-0.10)himbacine (M4-subtype selective; 7.32+/-0.18)pirenzepine (M1-subtype selective; 6.78+/-0.16)methoctramine (M2-subtype selective; 5.51+/-0.43). In sharp contrast, CCh concentration-dependently reduced the 80 mM KCl-induced contraction in longitudinal ureteral preparations, the pD(2) value being 4.83+/-0.10. On this CCh-induced ureteral relaxation, the rank order of antagonistic potencies (apparent pA(2)) was atropine (8.56+/-0.09)4-DAMP (7.63+/-0.21)himbacine (7.46+/-0.09)methoctramine (6.54+/-0.18)pirenzepine (6.33+/-0.22). The nitric-oxide-synthase inhibitor N(omega)-nitro-L-arginine (L-NOARG; 1 x 10(-4) M) had no effect on the CCh-induced ureteral relaxation. These data suggest that the CCh-induced rhythmic contraction in the spiral preparation was mediated via the M3-receptor, while the CCh-induced relaxation in the longitudinal preparation was probably mediated mainly via the M4-receptor. |
| Databáze: | OpenAIRE |
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