Airway smooth muscle photorelaxation via opsin receptor activation

Non-visual opsin receptors have recently been implicated in blue light mediated photorelaxation of smooth muscle in various organs. Since photorelaxation has not yet been demonstrated in airway smooth muscle (ASM) or in human tissues, we questioned whether functional opsin receptors are expressed in mouse and human ASM. Messenger RNA encoding the opsin 3 receptor was detected in both human and mouse airway smooth muscle. To demonstrate the functionality of the opsin receptors, we performed wire myography of ex vivo airway smooth muscle from mouse and human upper airways. Blue light mediated relaxation of acetylcholine pre-constricted airways was intensity and wavelength dependent (maximum relaxation at 430 nm blue light) and was inhibited by blockade of the large conductance calcium-activated potassium (BK) channels with iberiotoxin. We further implicated opsin receptors as key mediators in functional photorelaxation by demonstrating increased relaxation in the presence of a G protein receptor kinase 2 (G...