Department of Physiology, Shanghai Jiaotong University School of Medicine, 800 Dongchuan Road, 328 Wenxuan Medical Building, Shanghai 200240, China.
Eur J Pharmacol. 2011 Dec 30;673(1-3):85-95. doi: 10.1016/j.ejphar.2011.10.018. Epub 2011 Oct 25.
The present study was designed to investigate the effect of endogenous hydrogen sulfide (H₂S) on gastric motility in mice. Western blotting and immunocytochemistry were used to determine expression levels of the H₂S-producing enzymes cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE) in gastric tissues and cultured smooth muscle cells. Physiological and intracellular recordings and the whole-cell patch clamp technique were used to evaluate the effect of H₂S on the mechanical and electrical activities in muscle strips and in isolated smooth muscle cells, respectively. The results showed that CBS and CSE were expressed in mouse gastric smooth muscle. NaHS, a H₂S donor, inhibited the amplitude and frequency of spontaneous contraction at high concentrations (>200 μM). However, NaHS at low concentrations (<100 μM) enhanced the basal tension and increased the contractile amplitude of muscle strips. This excitatory effect was not altered by the blockade of the enteric nerve with TTX, but was abolished by tetraethylammonium (TEA) or 4-aminopyridine (4-AP). Aminooxyacetic acid (AOA), but not propargylglycine (PAG), caused a concentration-dependent inhibition of spontaneous contraction. This effect was restored by L-cysteine and NaHS. In addition, NaHS at low concentrations (<100 μM) produced a depolarization of the membrane potential, whereas AOA hyperpolarized the membrane potential and decreased the amplitude of slow waves. Furthermore, AOA increased whole-cell delayed rectifier K⁺ current (I(K(V))). These findings suggest that endogenous H₂S appears to be an excitatory gaseous mediator during physiological regulation of gastric motility and this excitable effect is mediated by depolarization of the membrane potential via inhibition of I(K(V)).
本研究旨在探讨内源性硫化氢（H₂S）对小鼠胃动力的影响。采用 Western blot 和免疫细胞化学法测定胃组织和培养平滑肌细胞中 H₂S 产生酶胱硫醚-β-合酶（CBS）和胱硫醚-γ-裂解酶（CSE）的表达水平。生理和细胞内记录以及全细胞膜片钳技术分别用于评估 H₂S 对肌条机械和电活动的影响，以及对分离平滑肌细胞的影响。结果表明，CBS 和 CSE 在小鼠胃平滑肌中表达。H₂S 供体 NaHS 在高浓度（>200 μM）时抑制自发性收缩的幅度和频率。然而，低浓度（<100 μM）的 NaHS 增强了肌条的基础张力并增加了收缩幅度。这种兴奋作用不受 TTX 阻断肠神经的影响，但被四乙铵（TEA）或 4-氨基吡啶（4-AP）消除。氨基氧乙酸（AOA），但不是炔丙基甘氨酸（PAG），可引起自发性收缩的浓度依赖性抑制。这种作用可被 L-半胱氨酸和 NaHS 恢复。此外，低浓度（<100 μM）的 NaHS 导致膜电位去极化，而 AOA 则使膜电位超极化并降低慢波幅度。此外，AOA 增加了全细胞延迟整流钾电流（I(K(V)))。这些发现表明，内源性 H₂S 似乎是生理调节胃动力过程中的一种兴奋性气体介质，这种兴奋作用是通过抑制 I(K(V))) 来实现膜电位去极化介导的。
