Hydrogen sulphide‐induced relaxation of porcine peripheral bronchioles

Abstract

BACKGROUND AND PURPOSEHydrogen sulphide (H2S) is an endogenous gasotransmitter. Although it has been shown to elicit responses in vascular and other smooth muscle preparations, a role for endogenously produced H2S in mediating airway tone has yet to be demonstrated. Therefore, the aim of this study was to determine whether H2S is produced within the airways and to determine the functional effect on airway tone. EXPERIMENTAL APPROACHSmall peripheral airways (<5 mm in diameter) from porcine lungs were set up in isolated tissue baths, pre-contracted with the muscarinic agonist carbachol, and then exposed to either the H2S donor sodium hydrosulphide (NaHS), or the precursor L-cysteine. H2S production from L-cysteine or 3-mercaptopyruvate in tissue homogenates was measured by the methylene blue assay. Expression of the H2S-synthesizing enzymes cystathionine b-synthase (CBS), cystathionine g lyase (CSE) and 3-mercaptopyruvate sulphurtransferase (3-MST) were measured by Western blotting. KEY RESULTSNaHS caused a large relaxation of the airways, which was inhibited partially by pre-contraction with KCl or exposure to tetraethylammonium, but not glibenclamide, paxilline or 4-aminopyridine. L-cysteine also caused a relaxation of the airways which was inhibited by the CBS inhibitor aminooxyacetic acid. Tissue homogenates from airways exposed to L-cysteine or 3-mercaptopyruvate in vitro showed a significant production of H2S. Western blotting demonstrated immunoreactivity to CBS, CSE and 3-MST enzymes in the airways. CONCLUSIONS AND IMPLICATIONSThese data demonstrate that H2S can be produced endogenously within porcine airways causing relaxation. The mechanism of relaxation depends, in part, on K + channel activity. Abbreviations

Hydrogen sulfide decreases β-adrenergic agonist-stimulated lung liquid clearance by inhibiting ENaC-mediated transepithelial sodium absorption

“…This loss of H 2S from buffers was initially determined by measuring H2S concentrations at various time points after application of 5 ϫ 10 Ϫ5 M Na2S to H441 Ringer solution (for composition, see below). H2S was measured by the formation of methylene blue exactly as previously described (70). Methylene blue/H2S levels stayed constant for up to 5 min postapplication of Na2S and decreased afterward to baseline levels ( Fig.…”

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“…Similar to colon tumours, colon adenocarcinoma‐derived cell lines (HCT116, HT‐29, LoVo) exhibit selective up‐regulation of CBS when compared with NCM356 cells (a non‐tumorigenic control human epithelial cell line) (Figure A,B). Homogenates of the patient‐derived colon tumour specimens, as well as homogenates of the colon cancer‐derived cell lines, exhibit an increased rate of H 2 S production, which is blocked by the CBS inhibitor aminooxyacetic acid (AOAA), a widely used CBS inhibitor (Abe and Kimura, ; Julian et al ., ; Austgen et al ., ; Han et al ., ; Asimakopoulou et al ., ; Rashid et al ., ; Wang et al ., ). However, H 2 S production was not significantly inhibited by the CSE inhibitor PAG.…”

Emerging role of hydrogen sulfide in hypertension and related cardiovascular diseases

“…In tissue bath preparations of small peripheral airways (<5 mm in diameter) from porcine lungs precontracted with the muscarinic ACh receptor agonist carbachol, both H2S donor NaHS and the precursor L-cysteine causes a large relaxation of the airways (Rashid et al, 2013). Ariyaratnam et al found that 500 μM NaHS causes a reduction in both pulmonary artery and bronchial airway pressures (Ariyaratnam et al, 2013).…”