Plasticity of osmoregulatory function in the killifish intestine: drinking rates, salt and water transport, and gene expression after freshwater transfer
Plasticity of osmoregulatory function in the killifish intestine: drinking rates, salt and water transport, and gene expression after freshwater transfer
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鳉鱼肠道渗透调节功能的可塑性：饮水率、盐和水运输以及淡水转移后的基因表达
DOI：
10.1242/jeb.02462
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发表时间：
2006
影响因子：
2.8
通讯作者：
C. Wood
中科院分区：
文献类型：
--
作者：
G. Scott;P. Schulte;C. Wood
摘要本研究探讨了微咸水(10%海水)移入淡水后，异地锦鲤肠道功能的变化。血浆Na+和Cl-浓度在移植后12h下降，但在7d后恢复。饮水率在12h显著下降(为对照值的32%)，在淡水中3d和7d后仍受到抑制(34%和43%)。相反，体外测得的肠道吸水率有一过性增加(12h和3d分别为3.3和2.6倍)，7天后恢复到基线水平。吸水率的变化完全可以用净离子通量的变化来解释：吸水率与净Na+和净氯离子通量之和(3.42±0.10mol.L水μ-1离子)之间存在极强的相关性(R2=0.960)。然而，淡水中增强的肠道离子传输可能不会增加体内的水分摄取量，因为饮酒率远远低于肠道吸收水分的能力。当食物中的离子存在于肠道中时，淡水转移后增加的肠道离子吸收可能反而有助于促进食物中的离子吸收。净离子通量的调节没有改变许多离子转运体(Na+/K+-ATPaseα1a、碳酸氢酶2、CFTRCl-通道、Na+/K+/2Cl-共转运体2和信号蛋白14-3-3a)的基因水平，而且在第3天Na+/K+-ATPase活性增加之前发生了调节，这表明存在其他机制导致离子转运量增加。有趣的是，净氯离子通量总是超过净钠离子通量，这可能是为了帮助维持氯离子平衡和/或促进碳酸氢盐的排泄。我们的结果表明，在转移到淡水中的离子扰动最严重的时期，肠道对食物中的氯化钠的吸收是重要的，这为进一步深入了解鲤鱼常盐度的机制提供了依据。
SUMMARY We have explored intestinal function in the euryhaline killifish Fundulus heteroclitus after transfer from brackish water (10% seawater) to fresh water. Plasma Na+ and Cl– concentrations fell at 12 h post-transfer, but recovered by 7 days. Drinking rate decreased substantially at 12 h (32% of control value) and remained suppressed after 3 and 7 days in fresh water (34 and 43%). By contrast, there was a transient increase in the capacity for water absorption measured across isolated intestines in vitro (3.3- and 2.6-fold at 12 h and 3 days), which returned to baseline after 7 days. These changes in water absorption could be entirely accounted for by changes in net ion flux: there was an extremely strong correlation (R2=0.960) between water absorption and the sum of net Na+ and net Cl– fluxes (3.42±0.10 μl water μmol–1 ion). However, enhanced ion transport across the intestine in fresh water would probably not increase water uptake in vivo, because the drinking rate was far less than the capacity for water absorption across the intestine. The increased intestinal ion absorption after freshwater transfer may instead serve to facilitate ion absorption from food when it is present in the gut. Modulation of net ion flux occurred without changes in mRNA levels of many ion transporters (Na+/K+-ATPase α1a, carbonic anhydrase 2, CFTR Cl– channel, Na+/K+/2Cl– cotransporter 2, and the signalling protein 14-3-3a), and before a measured increase in Na+/K+-ATPase activity at 3 days, suggesting that there is some other mechanism responsible for increasing ion transport. Interestingly, net Cl– flux always exceeded net Na+ flux, possibly to help maintain Cl– balance and/or facilitate bicarbonate excretion. Our results suggest that intestinal NaCl absorption from food is important during the period of greatest ionic disturbance after transfer to fresh water, and provide further insight into the mechanisms of euryhalinity in killifish.
影响因子：
5.5
作者：
Scott, GR;Richards, JG;Schulte, PM
通讯作者：
Schulte, PM