Search

Aims: This study focused on investigating whether NS8593 reverses airway smooth muscle (ASM) contraction and the underlying mechanism., Main Methods: ASM contraction in mouse tracheal rings and lung slices was measured. Currents mediated by voltage dependent Ca 2+ channels (VDCCs) and ACH-activated channels were measured using the whole-cell patch-clamp technique in single tracheal smooth muscle cells (TSMCs). Intracellular Ca 2+ level and cell length were measured using an LSM 700 laser confocal microscope and a Zen 2010 software. Mouse respiratory system resistance (Rrs) was assessed using a FlexiVent FX system., Key Findings: High K + (80 mM K + ) and ACH induced ASM contraction in mouse tracheal rings and lung slices, which was partially relaxed by nifedipine (blocker of L-type VDCCs, LVDCCs), YM-58483 (blocker of store-operated Ca 2+ entry (SOCE), transient receptor potential C3 (TRPC3) and TRPC5 channels), respectively. However, the contraction was completely reversed by NS8593, whereas, slightly relaxed by formoterol. ACH activated inward currents, which displayed linear and reversed around 0 mV, indicating the currents were mediated by non-selective cation channels (NSCCs). Moreover, these currents were blocked by YM-58483. In addition, such currents were abolished by NS8593, implicating that NS8593 inhibits the same channels. Besides, NS8593 inhibited increases of intracellular Ca 2+ and the associated cell shortening. Finally, NS8593 inhibited ACH-induced increases of mouse respirator system resistance (Rrs)., Significance: Our results indicate that NS8593 inhibits LVDCCs and NSCCs, resulting in decreases of intracellular Ca 2+ and then leading to ASM relaxation. These data suggest that NS8593 might be a new bronchodilator., (Copyright © 2019. Published by Elsevier Inc.)

The effects of hypertonic solution on airway smooth muscle (ASM) contraction and the underlying mechanisms are largely unknown. We found that hypertonic saline (HS) inhibited acetylcholine (ACh)-induced contraction of ASM from the mouse trachea and human bronchi. In single mouse ASM cells (ASMCs), ACh induced an increase in intracellular Ca 2+ that was further enhanced by 5% NaCl, indicating that the HS-induced inhibition of ASM contraction was not mediated by a decrease in cytosolic Ca 2+ . The Rho-associated kinase (ROCK) inhibitor Y-27632 relaxed ACh-induced precontraction of mouse tracheal rings. However, such inhibition was not observed after the relaxation induced by 5% NaCl. Moreover, the incubation of mouse tracheal rings with 5% NaCl decreased ACh-induced phosphorylation of myosin light chain 20 and myosin phosphatase target subunit 1. These data indicate that HS inhibits the contraction of ASM by inhibiting Ca 2+ sensitization, not by decreasing intracellular Ca 2+ ., (© 2017 John Wiley & Sons Australia, Ltd.)

The effects of hypertonic solution on airway smooth muscle ( ASM) contraction and the underlying mechanisms are largely unknown. We found that hypertonic saline ( HS) inhibited acetylcholine ( ACh)-induced contraction of ASM from the mouse trachea and human bronchi. In single mouse ASM cells ( ASMCs), ACh induced an increase in intracellular Ca2+ that was further enhanced by 5% NaCl, indicating that the HS-induced inhibition of ASM contraction was not mediated by a decrease in cytosolic Ca2+. The Rho-associated kinase ( ROCK) inhibitor Y-27632 relaxed ACh-induced precontraction of mouse tracheal rings. However, such inhibition was not observed after the relaxation induced by 5% NaCl. Moreover, the incubation of mouse tracheal rings with 5% NaCl decreased ACh-induced phosphorylation of myosin light chain 20 and myosin phosphatase target subunit 1. These data indicate that HS inhibits the contraction of ASM by inhibiting Ca2+ sensitization, not by decreasing intracellular Ca2+. [ABSTRACT FROM AUTHOR]