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Updated: Aug 29, 2026

In vitro Measurements of Tracheal Constriction Using Mice
Published on: June 25, 2012
8Br-cGMP mediates relaxation of tracheal smooth muscle through PKA
Paola Algara-Suárez1, Ricardo Espinosa-Tanguma
1Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad Autónoma de San Luis Potosi, S.L.P. 78210, San Luis Potosí, Mexico.
Abstract:
In this study, guinea pig tracheal smooth muscle pre-contracted with histamine was relaxed by the addition of 100microM 8Br-cGMP, a non-hydrolyzable and cell-permeable analog for cGMP. This effect was not sensitive to cGMP-dependent protein kinase (PKG) inhibitors, whereas it was partially blocked by cAMP-dependent protein kinase (PKA) inhibitors. The relaxation observed was also reverted up to 50+/-8.5% by iberiotoxin, a selective inhibitor of large conductance, calcium-activated potassium channels (BK(Ca)). Our results indicate that there exists a crosstalk mechanism between cAMP and cGMP signaling pathways which lead to relaxation of guinea pig tracheal smooth muscle and also that BK(Ca) channels are involved to a certain extent in this phenomenon.
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