Impacto do efluxo do AMP cíclico induzido pelos agonistas de adrenoceptores β2 e inibidores de fosfodiesterases no relaxamento do músculo liso das vias aéreas do rato
Data
2022
Autores
Satori, Naiara Ayako 
Orientadores
Godinho, Rosely Oliveira
Tipo
Dissertação de mestrado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Os agonistas de adrenoceptores β2 e os inibidores de fosfodiesterases (PDE) são classes
de fármacos broncodilatadores que tem como mecanismo de ação comum a capacidade de
aumentar o 3’-5’-AMP cíclico (AMPc) intracelular. Estudos anteriores do nosso grupo,
utilizando músculo esquelético e traqueia de rato, mostraram que os agonistas de
adrenoceptores β2 induzem o aumento do AMPc intracelular seguido por seu efluxo e
aumento do AMPc extracelular (Godinho, Costa Jr, 2003; Chiavegatti, et al., 2008; Pacini, et
al., 2018). No meio extracelular, o AMPc é convertido no nucleosídeo broncoconstritor
adenosina por ectoenzimas denominadas ecto-PDE e ecto-5’-nucleodidases (ecto-5’-NT)
(Chiavegatti, et al., 2008; Pacini, et al., 2021). Não é conhecido, porém se os inibidores de PDE
são capazes de promover o efluxo do AMPc nem a interferência do AMPc extracelular no
relaxamento das vias aéreas induzido por esses fármacos. Desta forma, no presente trabalho
avaliamos o efeito dos inibidores de PDE IBMX e aminofilina (não-seletivos), roflumilaste
(seletivo de PDE4) no efluxo de AMPc e no relaxamento de traqueia de ratos, comparando-os
com os efeitos promovidos pelos agonistas de adrenoceptores β2, formoterol e salbutamol.
Através da dosagem por imunoensaio do AMPc do meio de incubação, demostramos que
tanto o formoterol quanto o IBMX, aminofilina e roflumilaste, aumentaram significativamente
as concentrações extracelulares de AMPc, comparativamente aos resultados obtidos em
traqueias tradadas apenas com o veículo. Demostramos também que a inibição dos
transportadores envolvidos no efluxo do AMPc com MK-571 impediu o aumento do AMPc
extracelular induzido por esses fármacos. Todos os broncodilatadores listados acima
promoveram o relaxamento de traqueias de rato pré-contraídas com carbacol. Nossos
resultados demostraram ainda que os inibidores do efluxo do AMPc (MK-571) e da ecto-5’-NT
(AMPCP) e o antagonista de receptores de adenosina (CGS-15943) causaram a potencialização
do relaxamento induzido pelo formoterol e o aumento do efeito máximo do salbutamol,
enquanto CGS-15943 ademais causou a potencialização do relaxamento induzido pelo
salbutamol. No entanto esses fármacos não alteram o relaxamento dos inibidores de PDE
testados. Em resumo, nossos dados mostram que todos os broncodilatadores testados foram
capazes de induzir o efluxo de AMPc, com impactos diferentes no relaxamento da musculatura
lisa traqueal na dependência do tipo de fármaco utilizado.
β2-adrenoceptor agonists and phosphodiesterase (PDE) inhibitors are types of bronchodilator drugs whose mechanism of action involves the increase intracellular cyclic 3'-5'-AMP (cAMP). Previous studies of our group showed that β2-adrenoceptor agonists induce an increase in intracellular cAMP followed by its efflux and increase in the extracellular cAMP of skeletal muscle and rat trachea (Godinho, Costa Jr, 2003; Chiavegatti, et al., 2008; Pacini, et al., 2018). In the extracellular medium, cAMP is converted into the bronchoconstrictor nucleoside adenosine by the ectoenzymes ecto-phosphodiesterases (ecto-PDE) and ecto-5'- nucleodidases (ecto-5'-NT) (Chiavegatti, et al., 2008; Pacini, et al., 2008; Pacini, et al. al., 2021). However, it is not known if PDE inhibitors are able to promote the efflux of cAMP or if the extracellular cAMP might interfere in the airway relaxation induced by these drugs. Thus, in the present work we evaluated the effect of PDE inhibitors IBMX and aminophylline (nonselective), roflumilast (selective for PDE4) on the efflux of cAMP and on the relaxation of the trachea of Wistar rats, comparing them with the effects promoted by the β2 adrenoceptor agonists formoterol and salbutamol. Using the method of immunoassay to measure the levels of cAMP in the incubation medium, we showed that formoterol, IBMX, aminophylline and roflumilast significantly increased extracellular concentrations of cAMP, compared to the results obtained in tracheas treated with the vehicle alone. We also demonstrated that inhibition of transporters involved in cAMP efflux with MK-571 prevented the increase in extracellular cAMP induced by these drugs. All the bronchodilators listed above promoted relaxation of carbachol pre-contracted rat tracheas. Our results also showed that inhibitors of either cAMP efflux (MK-571) or ecto-5'-NT (AMPCP) and the adenosine receptor antagonist CGS-15943 potentiated the formoterol-induced relaxation and increased the maximal effect of salbutamol. CGS-15943 also caused the potentiation of the relaxation induced by salbutamol. However, these drugs did not modify the relaxation induced by the PDE inhibitors. In summary, our data show that all bronchodilators were able to induce cAMP efflux, with different impacts on tracheal smooth muscle relaxation depending on the type of drug used
β2-adrenoceptor agonists and phosphodiesterase (PDE) inhibitors are types of bronchodilator drugs whose mechanism of action involves the increase intracellular cyclic 3'-5'-AMP (cAMP). Previous studies of our group showed that β2-adrenoceptor agonists induce an increase in intracellular cAMP followed by its efflux and increase in the extracellular cAMP of skeletal muscle and rat trachea (Godinho, Costa Jr, 2003; Chiavegatti, et al., 2008; Pacini, et al., 2018). In the extracellular medium, cAMP is converted into the bronchoconstrictor nucleoside adenosine by the ectoenzymes ecto-phosphodiesterases (ecto-PDE) and ecto-5'- nucleodidases (ecto-5'-NT) (Chiavegatti, et al., 2008; Pacini, et al., 2008; Pacini, et al. al., 2021). However, it is not known if PDE inhibitors are able to promote the efflux of cAMP or if the extracellular cAMP might interfere in the airway relaxation induced by these drugs. Thus, in the present work we evaluated the effect of PDE inhibitors IBMX and aminophylline (nonselective), roflumilast (selective for PDE4) on the efflux of cAMP and on the relaxation of the trachea of Wistar rats, comparing them with the effects promoted by the β2 adrenoceptor agonists formoterol and salbutamol. Using the method of immunoassay to measure the levels of cAMP in the incubation medium, we showed that formoterol, IBMX, aminophylline and roflumilast significantly increased extracellular concentrations of cAMP, compared to the results obtained in tracheas treated with the vehicle alone. We also demonstrated that inhibition of transporters involved in cAMP efflux with MK-571 prevented the increase in extracellular cAMP induced by these drugs. All the bronchodilators listed above promoted relaxation of carbachol pre-contracted rat tracheas. Our results also showed that inhibitors of either cAMP efflux (MK-571) or ecto-5'-NT (AMPCP) and the adenosine receptor antagonist CGS-15943 potentiated the formoterol-induced relaxation and increased the maximal effect of salbutamol. CGS-15943 also caused the potentiation of the relaxation induced by salbutamol. However, these drugs did not modify the relaxation induced by the PDE inhibitors. In summary, our data show that all bronchodilators were able to induce cAMP efflux, with different impacts on tracheal smooth muscle relaxation depending on the type of drug used
Descrição
Citação
SATORI, N. A. Impacto do efluxo do AMP cíclico induzido pelos agonistas de adrenoceptores β2 e inibidores de fosfodiesterases no relaxamento do músculo liso das vias aéreas do rato. São Paulo, 2022. 45 f. Dissertação (Mestrado em Farmacologia) - Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP). São Paulo, 2022.