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Updated: Jul 15, 2026

In vitro Measurements of Tracheal Constriction Using Mice
Published on: June 25, 2012
Relaxing effects of 5-oxo-ETE on human bronchi involve BK Ca channel activation
Caroline Morin1, Marco Sirois, Vincent Echave
1Le Bilarium, Department of Physiology and Biophysics, Faculty of Medicine and Health Sciences, Université de Sherbrooke 3001, 12th Avenue North, Sherbrooke J1H 5N4, Que., Canada.
Abstract:
The present study investigated the ability of 5-oxo-EicosaTetraEnoic acid (5-oxo-ETE) for modulating airway smooth muscle (ASM) tone in human bronchi. 5-Oxo-ETE induced a concentration-dependent relaxing effect on human bronchi pre-contracted with methacholine (MCh) and arachidonic acid (AA). This relaxing response was highly sensitive to Iberiotoxin (IbTx), a large conducting Ca(2+)-activated K(+) channel (BK(Ca)) inhibitor. Furthermore, microelectrode measurements revealed that 5-oxo-ETE (0.1-10 microM) hyperpolarizes the membrane potential of human bronchial ASM cells. These hyperpolarizing effects were also inhibited in the presence of 10nM IbTx. Lastly, 5-oxo-ETE was shown to directly activate reconstituted BK(Ca) channels derived from human airway smooth muscles. In summary, the 5-oxo-ETE eicosanoid activates a specific K(+) conductance, involved in membrane hyperpolarization, which in turn reduces Ca(2+) entry and facilitates relaxation of smooth muscle cells.
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