H2S relaxes isolated human airway smooth muscle cells via the sarcolemmal KATP channel

Abstract

Here we explored the impact of hydrogen sulfide (H2S) on biophysical properties of the primary human airway smooth muscle (ASM)–the end effector of acute airway narrowing in asthma. Using Magnetic Twisting Cytometry (MTC), we measured dynamic changes in the stiffness of isolated ASM, at the single-cell level, in response to varying doses of GYY4137 (1–10 mM). GYY4137 slowly released appreciable levels of H2S in the range of 10–275 µM, and H2S released was long lived. In isolated human ASM cells, GYY4137 acutely decreased stiffness (i.e. an indicator of the single-cell relaxation) in a dose-dependent fashion, and stiffness decreases were sustained in culture for 24h. Human ASM cells showed protein expressions of cystathionine-γ-lyase (CSE; a H2S synthesizing enzyme) and ATP-sensitive potassium (KATP) channels. The KATP channel opener pinacidil effectively relaxed isolated ASM cells. In addition, pinacidil-induced ASM relaxation was completely inhibited by the treatment of cells with the KATP channel blocker glibenclamide. Glibenclamide also markedly attenuated GYY4137-mediated relaxation of isolated human ASM cells. Taken together, our findings demonstrate that H2S causes the relaxation of human ASM and implicate as well the role for sarcolemmal KATP channels. Finally, given that ASM cells express intrinsic enzymatic machinery of generating H2S, we suggest thereby this class of gasotransmitter can be further exploited for potential therapy against obstructive lung disease.

GYY4137, a Novel Water-Soluble, H2S-Releasing Molecule

“…A similar smooth muscle relaxant effect of GYY4137 has now been described in a range of tissues including human airway smooth muscle cells via opening of sarcolemma K ATP channels (Fitzgerald et al, 2014), mouse intrapulmonary airways by an effect on intracellular calcium release (Castro-Piedras & Perez-Zoghbi, 2013), pig bladder neck tissues again by opening K ATP channels (Fernandes et al, 2013), pregnant rat myometrial smooth muscle cells (Robinson & Wray, 2012) and in the bovine ciliary artery (Chitnis et al, 2013). Intriguingly, GYY4137 can occasionally, and in defined conditions, exert the opposite effect on blood vessels.…”

Medicinal Chemistry: Insights into the Development of Novel H2S Donors

“…However, GYY4137 exhibited a much slower (~10 min) vasodilation. In a different study, Fitzgerald and co-workers demonstrated the single-cell level relaxation effects of GYY4137 on airway smooth muscle (ASM) (Fitzgerald et al 2014). In this experiment, H 2 S release from GYY4137 in culture media was confirmed by a methylene blue (MB) assay.…”

H2S and Blood Vessels: An Overview

“…Furthermore, inhibition of endogenous H 2 S production with PPG reduced whole-cell K ATP currents. H 2 S also causes the relaxation of human airway SMCs via stimulating sarcolemmal K ATP channels (Fitzgerald et al 2014). Other studies proved that H 2 S interacts with the SUR subunits of the K ATP channel complex to cause the channel to open, and the sulfhydryl groups located on the extracellular surface of the SUR subunits are potential targets for H 2 S S-sulfhydration (Jiang et al 2010).…”