Hydrogen Sulfide Regulates Ca²⁺ Homeostasis Mediated by Concomitantly Produced Nitric Oxide via a Novel Synergistic Pathway in Exocrine Pancreas

Abstract

Aim: The present study was designed to explore the effects of hydrogen sulfide (H 2 S) on Ca 2+ homeostasis in rat pancreatic acini. Results: Sodium hydrosulfide (NaHS; an H 2 S donor) induced a biphasic increase in the in- ] i increase was markedly inhibited in the presence of NG-monomethyl L-arginine or 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), and diaminofluorescein-2/diaminofluorescein-2 triazole (DAF-2/DAF-2T) fluorometry demonstrated that nitric oxide (NO) was also produced by H 2 S in a dose-dependent manner with an EC 50 of 64.8 lM, indicating that NO was involved in the H 2 S effect. The H 2 S-induced [Ca 2+ ] i increase was inhibited by pretreatment with U73122, xestospongin C, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, KT5823, and GP2A, indicating that phospholipase C (PLC), the inositol 1,4,5-trisphosphate (IP 3 ) receptor, soluble guanylate cyclase (sGC), protein kinase G (PKG), and G q -protein play roles as intermediate components in the H 2 S-triggered intracellular signaling. Innovation: To our knowledge, our study is the first one highlighting the effect of H 2 S on intracellular Ca 2+ dynamics in pancreatic acinar cells. Moreover, a novel cascade was presumed to function via the synergistic interaction between H 2 S and NO. Conclusion: We conclude that H 2 S affects [Ca 2+ ] i homeostasis that is mediated by H 2 S-evoked NO production via an endothelial nitric oxide synthase (eNOS)-NO-sGC-cyclic guanosine monophosphate-PKG-G q -protein-PLC-IP 3 pathway to induce Ca 2+ release, and this pathway is identical to the one we recently proposed for a sole effect of NO and the two gaseous molecules synergistically function to regulate Ca 2+ homeostasis. Antioxid. Redox Signal. 20, 747-758.

Regulation of soluble guanylate cyclase by matricellular thrombospondins: implications for blood flow

“…In pancreatic acini, H 2 S was found to increase Ca 2+ levels (Moustafa and Habara, 2014). The elevated calcium levels were shown to increase NO synthesis, consistent with the known calcium regulation of eNOS.…”

A novel role for carbon monoxide as a potent regulator of intracellular Ca2+ and nitric oxide in rat pancreatic acinar cells

“…Freshly isolated pancreatic acini were prepared according to a previously reported method (42,43). In brief, the pancreata were excised, freed from fat and lymph nodes and injected with 5 ml of HEPES-buffered standard solution containing 60-75 U/ml collagenase supplemented with 0.1 mg/ml soybean trypsin inhibitor.…”

“…and NO levels, an imaging system was used as previously reported (42,43). Briefly, isolated acini were loaded with final concentrations of 10 μM Fluo-3/AM or 10 μM DAF-2/DA in the standard solution with mild shaking in the dark for 60 min at 37°C.…”

“…Photodamage was minimized by attenuating the laser intensity with a neutral density filter interposed into the illumination path (1% transmission was sufficient to obtain fluorescence). (42,43). All experiments for the measurement of [Ca 2+ ] i and NO were performed at room temperature and isolated acini were used for experiments within 4 h of isolation.…”

Chloride channels mediate sodium sulphide‐induced relaxation in rat uteri

“…Moreover, it was shown to reduce the intracellular Ca 2+ transients that underlie spontaneous myometrium contractions (Robinson and Wray, 2012). Hydrogen sulphide's effects on intracellular Ca 2+ were inhibited in the presence of the sGC inhibitor (Moustafa and Habara, 2014). Additionally, cAMP and cGMP were shown to be important in the regulation of uterine contractility (Aguilar and Mitchell, 2010).…”