Kumai Yusuke, Porteus Cosima S, Kwong Raymond W M, Perry Steve F
Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada.
Pflugers Arch. 2015 Apr;467(4):651-64. doi: 10.1007/s00424-014-1550-y. Epub 2014 Jun 18.
The present study investigated the role of hydrogen sulfide (H2S) in regulating Na(+) uptake in larval zebrafish, Danio rerio. Waterborne treatment of larvae at 4 days post-fertilization (dpf) with Na2S or GYY-4137 (chemicals known to generate H2S) significantly reduced Na(+) uptake. Exposure of larvae to water enriched with NaCl (1 mM NaCl) caused a pronounced reduction in Na(+) uptake which was prevented by pharmacological inhibition of cystathionine β-synthase (CBS) or cystathionine γ-lyase (CSE), two key enzymes involved in the endogenous synthesis of H2S. Furthermore, translational gene knockdown of CSE and CBSb significantly increased the basal rate of Na(+) uptake. Waterborne treatment with Na2S significantly decreased whole-body acid excretion and reduced Na(+) uptake in larval zebrafish preexposed to acidic (pH 4.0) water (a condition shown to promote Na(+) uptake via Na(+)-H(+)-exchanger 3b, NHE3b). However, Na2S did not affect Na(+) uptake in larvae depleted of NHE3b-containing ionocytes (HR cells) after knockdown of transcription factor glial cell missing 2 (gcm2) in which Na(+) uptake occurs predominantly via Na(+)-Cl(-) co-transporter (NCC)-containing cells. These observations suggest that Na(+) uptake via NHE3b, but not NCC, is regulated by H2S. Whole-mount immunohistochemistry demonstrated that ionocytes expressing NHE3b also express CSE. These data suggests a physiologically relevant role of H2S as a mechanism to lower Na(+) uptake in zebrafish larvae, probably through its inhibitory action on NHE3b.
本研究调查了硫化氢（H₂S）在调节斑马鱼幼体（Danio rerio）钠（Na⁺）摄取中的作用。在受精后4天（dpf）用水溶性Na₂S或GYY - 4137（已知可产生H₂S的化学物质）处理幼体，显著降低了Na⁺摄取。将幼体暴露于富含NaCl（1 mM NaCl）的水中会导致Na⁺摄取明显减少，而通过药理学抑制胱硫醚β-合酶（CBS）或胱硫醚γ-裂解酶（CSE）可防止这种情况，这两种关键酶参与内源性H₂S的合成。此外，对CSE和CBSb进行翻译基因敲低显著提高了Na⁺摄取的基础速率。用水溶性Na₂S处理显著降低了整体酸排泄，并减少了预先暴露于酸性（pH 4.0）水（一种显示可通过钠氢交换体3b（NHE3b）促进Na⁺摄取的条件）中的斑马鱼幼体的Na⁺摄取。然而，在转录因子神经胶质缺失2（gcm2）敲低后，Na⁺摄取主要通过含钠氯共转运体（NCC）的细胞发生，此时Na₂S对缺乏含NHE3b离子细胞（HR细胞）的幼体的Na⁺摄取没有影响。这些观察结果表明，通过NHE3b而非NCC的Na⁺摄取受H₂S调节。整装免疫组织化学显示，表达NHE3b的离子细胞也表达CSE。这些数据表明H₂S在斑马鱼幼体中作为降低Na⁺摄取的机制具有生理相关作用，可能是通过其对NHE3b的抑制作用实现的。
