The cholinomimetic agent bethanechol activates IK(ACh) in feline atrial myocytes
| Autor: | Ricardo A. Navarro-Polanco, José A. Sánchez-Chapula, Dora E. Benavides-Haro |
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| Rok vydání: | 2003 |
| Předmět: |
medicine.medical_specialty
Cholinergic Agents Bethanechol Muscarinic Antagonists Pharmacology Diamines In Vitro Techniques Muscarinic Agonists Membrane Potentials chemistry.chemical_compound Benzodiazepines Tropicamide Piperidines Internal medicine Muscarinic acetylcholine receptor Phenethylamines medicine Methoctramine Potassium Channel Blockers Animals Heart Atria Potassium Channels Inwardly Rectifying Receptor Tetramethylammonium Tertiapin Receptor Muscarinic M3 Muscle Cells Receptor Muscarinic M2 Sulfonamides Receptor Muscarinic M4 Receptor Muscarinic M1 General Medicine Potassium channel Bee Venoms Endocrinology chemistry Pilocarpine Barium Cats medicine.drug |
| Zdroj: | Naunyn-Schmiedeberg's archives of pharmacology. 368(4) |
| ISSN: | 0028-1298 |
| Popis: | The effect of the cholinomimetic agent, bethanechol on macroscopic membrane currents was studied in dispersed cat atrial myocytes, using the whole-cell patch-clamp technique. Bethanechol activated an inward rectifying potassium current similar to I(K(ACh)), and a delayed rectifying-like outward current, similar to I(KM3) activated by pilocarpine, choline, and tetramethylammonium, and I(KM4) activated by 4-aminopyridine. The relatively specific muscarinic receptors subtype antagonists methoctramine (M(2)), and tropicamide (M(4)) inhibited both current components induced by bethanechol, suggesting a lack of specificity of these antagonists on cat atrial myocytes. The specific antagonist of M(3) receptors, para-fluoro-hexahydro-siladifenidol did not significantly inhibit the bethanechol-induced currents. In addition, pretreatment with PTX prevented activation of the bethanechol-induced inward and outward currents, suggesting that M(3) receptors are probably not involved in the bethanechol action. The I(K(ACh)) specific blocker tertiapin inhibited both inward rectifying- and delayed rectifying-like currents. These results suggest that both current components result from activation of a single channel type, likely I(K(ACh)). |
| Databáze: | OpenAIRE |
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