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1.
J Pharmacol Sci ; 148(1): 51-55, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34924129

RESUMO

The present study aimed to characterize and compare ß-adrenoceptors in the rat bladder with those in the heart and lungs of SD rats (8-10 weeks old) using subtype-selective agonists and antagonists in a radioligand binding assay with (-)-[125I]cyanopindolol ([125I]CYP), and also to clarify alterations in ß-adrenoceptors in the bladder of spontaneously hypertensive rats (SHR) at 14 weeks old, from those of Wistar-Kyoto rats (WKY) and Wistar rats at the same age. A radioligand binding assay with [125I]CYP was used to measure ß-adrenoceptor binding activity in rat tissues. Metoprolol exhibited the highest affinity to specific binding sites of [125I]CYP in the rat heart, indicating the dominance of ß1-adrenoceptors. ß3-selective agonists (BRL37344 and CL316243) and antagonist (SR59230A) exhibited higher affinity to specific binding sites of [125I]CYP in the bladder than in the heart and lungs. Furthermore, the binding affinity of the ß2-selective antagonist, ICI118551 was the highest in the bladder. The Bmax of specific [125]CYP binding in the bladder was significantly lower in WKY and SHR than in Wistar rats. The present study provides further evidence for the coexistence of ß2-and ß3-adrenoceptors in the rat bladder, and indicates that ß-adrenoceptor density is lower in the bladders of WKY and SHR.


Assuntos
Pulmão/metabolismo , Miocárdio/metabolismo , Ratos Endogâmicos SHR/metabolismo , Receptores Adrenérgicos beta/metabolismo , Bexiga Urinária/metabolismo , Animais , Ensaio Radioligante/métodos , Ratos Endogâmicos WKY , Ratos Sprague-Dawley , Ratos Wistar , Receptores Adrenérgicos beta 1/metabolismo , Receptores Adrenérgicos beta 3/metabolismo
2.
J Pharmacol Sci ; 115(3): 374-82, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21358117

RESUMO

The aim of the current study was to characterize comparatively the binding of muscarinic receptor in the lung of rats intratracheally administered anticholinergic agents (tiotropium, ipratropium, glycopyrrolate) used clinically to treat chronic obstructive pulmonary disease (COPD) and asthma. Binding parameters of [N-methyl-(3)H]scopolamine methyl chloride ([(3)H]NMS) were determined in tissues (lung, bladder, submaxillary gland) of rats intratracheally administered tiotropium, ipratropium, and glycopyrrolate. The in vitro binding affinity of tiotropium for the receptors was 10-11-fold higher than those of ipratropium and glycopyrrolate. Intratracheal administration of tiotropium (0.6-6.4 nmol/kg) caused sustained (lasting at least 24 h) increase in the apparent dissociation constant (K(d)) for [(3)H]NMS binding in rat lung compared with the control value. Concomitantly, there was a long-lasting decrease in the maximal number of binding sites (B(max)) for [(3)H]NMS. Similary, ipratropium and glycopyrrolate at 7.3 and 7.5 nmol/kg, respectively, brought about a significant increase in K(d) for [(3)H]NMS binding. The effect by ipratropium was observed at 2 h but not 12 h, and that by glycopyrrolate lasted for 24 h. Both agents had little influence on the muscarinic receptors in the bladder and submaxillary gland. The present study provides the first evidence that tiotropium, ipratropium, and glycopyrrolate administered intratracheally in rats selectively bound muscarinic receptors of the lung, and tiotropium and glycopyrrolate had a much longer-lasting effect than ipratropium.


Assuntos
Glicopirrolato/metabolismo , Ipratrópio/metabolismo , Pulmão/metabolismo , Antagonistas Muscarínicos/metabolismo , Doença Pulmonar Obstrutiva Crônica/tratamento farmacológico , Receptores Muscarínicos/metabolismo , Derivados da Escopolamina/metabolismo , Animais , Sítios de Ligação , Broncodilatadores/administração & dosagem , Broncodilatadores/metabolismo , Broncodilatadores/farmacologia , Glicopirrolato/farmacologia , Coração/fisiologia , Ipratrópio/farmacologia , Pulmão/fisiopatologia , Masculino , Antagonistas Muscarínicos/administração & dosagem , Antagonistas Muscarínicos/farmacologia , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Ratos , Ratos Sprague-Dawley , Derivados da Escopolamina/farmacocinética , Glândula Submandibular/metabolismo , Brometo de Tiotrópio , Traqueia/efeitos dos fármacos , Bexiga Urinária/metabolismo
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