1. Validation of Fenoterol to Study β2-Adrenoceptor Function in the Rat Urinary Bladder.
- Author
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Erdogan BR, Yesilyurt ZE, Arioglu-Inan E, and Michel MC
- Subjects
- Adrenergic beta-2 Receptor Agonists therapeutic use, Adrenergic beta-Antagonists pharmacology, Adrenergic beta-Antagonists therapeutic use, Aminophenols pharmacology, Aminophenols therapeutic use, Animals, Carbachol pharmacology, Carbachol therapeutic use, Female, Fenoterol therapeutic use, Male, Muscle Contraction drug effects, Muscle Relaxation drug effects, Muscle, Smooth drug effects, Potassium Chloride pharmacology, Potassium Chloride therapeutic use, Propanolamines pharmacology, Propanolamines therapeutic use, Rats, Sprague-Dawley, Rats, Wistar, Sulfonamides pharmacology, Sulfonamides therapeutic use, Rats, Adrenergic beta-2 Receptor Agonists pharmacology, Fenoterol pharmacology, Urinary Bladder drug effects
- Abstract
Fenoterol is a β2-adrenoceptor (AR)-selective agonist that is commonly used to investigate relaxation responses mediated by β2-AR in smooth muscle preparations. Some data have questioned this because fenoterol had low potency in the rat urinary bladder when a muscarinic agonist was used as a pre-contraction agent and because some investigators proposed that fenoterol may act in part via β3-AR. We designed the present study to investigate whether fenoterol is a proper pharmacological tool to study β2-AR-mediated relaxation responses in the rat urinary bladder. Firstly, we have compared the effect of pre-contraction agents on fenoterol potency and found that fenoterol potency was about 1.5 log units greater against KCl than carbachol (pEC50 7.19 ± 0.66 and 5.62 ± 1.09 of KCl and of carbachol, respectively). To test the selectivity of fenoterol, we have determined the effects of the β2-AR antagonist ICI 118,551 and the β3-AR antagonist L 748,337 on relaxation responses to fenoterol. While 300 nM L 748,337 had little effect on the potency of fenoterol (pEC50 6.56 ± 0.25 and 6.33 ± 0.61 in the absence and presence of L 748,337, respectively), the relaxation curve for fenoterol was right-shifted in the presence 300 nM ICI 118,551 (pEC50 5.03 ± 0.18). Thus, we conclude that fenoterol is a proper pharmacological tool to assess β2-AR-mediated responses in the rat urinary bladder and most likely in other smooth-muscle preparations containing multiple subtypes of the β-AR., (© 2021 S. Karger AG, Basel.)
- Published
- 2022
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