Meng Xiang-Min, Huang Xu, Zhang Chun-Mei, Liu Dong-Hai, Lu Hong-Li, Kim Young-Chul, Xu Wen-Xie
Xiang-Min Meng, Xu Huang, Chun-Mei Zhang, Dong-Hai Liu, Hong-Li Lu, Wen-Xie Xu, Department of Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200240, China.
World J Gastroenterol. 2015 Apr 28;21(16):4840-51. doi: 10.3748/wjg.v21.i16.4840.
To investigate the effect of hydrogen sulfide (H2S) on smooth muscle motility in the gastric fundus.
The expression of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) in cultured smooth muscle cells from the gastric fundus was examined by the immunocytochemistry technique. The tension of the gastric fundus smooth muscle was recorded by an isometric force transducer under the condition of isometric contraction with each end of the smooth muscle strip tied with a silk thread. Intracellular recording was used to identify whether hydrogen sulfide affects the resting membrane potential of the gastric fundus in vitro. Cells were freshly separated from the gastric fundus of mice using a variety of enzyme digestion methods and whole-cell patch-clamp technique was used to find the effects of hydrogen sulfide on voltage-dependent potassium channel and calcium channel. Calcium imaging with fura-3AM loading was used to investigate the mechanism by which hydrogen sulfide regulates gastric fundus motility in cultured smooth muscle cells.
We found that both CBS and CSE were expressed in the cultured smooth muscle cells from the gastric fundus and that H2S increased the smooth muscle tension of the gastric fundus in mice at low concentrations. In addition, nicardipine and aminooxyacetic acid (AOAA), a CBS inhibitor, reduced the tension, whereas Nω-nitro-L-arginine methyl ester, a nonspecific nitric oxide synthase, increased the tension. The AOAA-induced relaxation was significantly recovered by H2S, and the NaHS-induced increase in tonic contraction was blocked by 5 mmol/L 4-aminopyridine and 1 μmol/L nicardipine. NaHS significantly depolarized the membrane potential and inhibited the voltage-dependent potassium currents. Moreover, NaHS increased L-type Ca(2+) currents and caused an elevation in intracellular calcium ([Ca(2+)]i).
These findings suggest that H2S may be an excitatory modulator in the gastric fundus in mice. The excitatory effect is mediated by voltage-dependent potassium and L-type calcium channels.
研究硫化氢（H₂S）对胃底平滑肌运动的影响。
采用免疫细胞化学技术检测胃底平滑肌细胞中胱硫醚β-合酶（CBS）和胱硫醚γ-裂解酶（CSE）的表达。用等长力传感器记录胃底平滑肌张力，平滑肌条两端用丝线结扎，在等长收缩条件下进行记录。采用细胞内记录法确定硫化氢在体外是否影响胃底的静息膜电位。用多种酶消化法从小鼠胃底新鲜分离细胞，采用全细胞膜片钳技术研究硫化氢对电压依赖性钾通道和钙通道的影响。用fura-3AM负载进行钙成像，以研究硫化氢调节培养的平滑肌细胞中胃底运动的机制。
我们发现CBS和CSE均在胃底培养的平滑肌细胞中表达，低浓度的H₂S可增加小鼠胃底平滑肌张力。此外，尼卡地平和CBS抑制剂氨基氧乙酸（AOAA）可降低张力，而非特异性一氧化氮合酶Nω-硝基-L-精氨酸甲酯可增加张力。AOAA诱导的舒张作用可被H₂S显著恢复，而NaHS诱导的紧张性收缩增加可被5 mmol/L 4-氨基吡啶和1 μmol/L尼卡地平阻断。NaHS使膜电位显著去极化并抑制电压依赖性钾电流。此外，NaHS增加L型Ca²⁺电流并导致细胞内钙（[Ca²⁺]i）升高。
这些发现表明H₂S可能是小鼠胃底的一种兴奋性调节剂。其兴奋作用由电压依赖性钾通道和L型钙通道介导。
