Ouabain-sensitive bicarbonate secretion and acid absorption by the marine teleost fish intestine play a role in osmoregulation
Ouabain-sensitive bicarbonate secretion and acid absorption by the marine teleost fish intestine play a role in osmoregulation
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DOI：
10.1152/ajpregu.00818.2005
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发表时间：
2006-10-01
期刊：
影响因子：
--
通讯作者：
Genz, J.
中科院分区：
文献类型：
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作者：
Grosell, M.;Genz, J.
海湾蟾鱼（Opsanus beta）肠道分泌的碱主要以HCO 3-的形式通过顶端阴离子交换来服务Cl-和水的吸收，以达到肠道调节的目的。在Ussing室中通过pH-统计技术测量的管腔HCO 3-分泌速率依赖于氧化能量代谢，并且对温度高度敏感。在25 ℃下，在体内样条件下，分泌速率平均为0.45 μ mol（.）cm（-2）（.）h（-1），其中0.25 μ mol（.）cm（-2）（.）h（-1）可以解释为碳酸酐酶部分催化的内源CO2水合作用。完全极性的分泌HCO 3-和H+所产生的CO2水合反应是显而易见的，从相等的速率管腔HCO 3-分泌通过阴离子交换和基底外侧H+挤出。当基底外侧H+挤出部分抑制血清pH值的降低，管腔HCO 3-分泌减少。基底外侧H+分泌通过乙基异丙氨氯地平不敏感机制与Na+交换，并最终由基底外侧Na+-K+-ATP酶的活性提供动力。蟾鱼肠道的液体吸收，以反对扩散的水损失到集中的海洋环境是伴随着大量的基底侧H+的挤出，密切联系的调节和酸碱平衡。
The gulf toadfish (Opsanus beta) intestine secretes base mainly in the form of HCO3- via apical anion exchange to serve Cl- and water absorption for osmoregulatory purposes. Luminal HCO3- secretion rates measured by pH-stat techniques in Ussing chambers rely on oxidative energy metabolism and are highly temperature sensitive. At 25 degrees C under in vivo-like conditions, secretion rates averaged 0.45 mu mol (.) cm(-2) (.) h(-1), of which 0.25 mu mol (.) cm(-2) (.) h(-1) can be accounted for by hydration of endogenous CO2 partly catalyzed by carbonic anhydrase. Complete polarity of secretion of HCO3- and H+ arising from the CO2 hydration reaction is evident from equal rates of luminal HCO3- secretion via anion exchange and basolateral H+ extrusion. When basolateral H+ extrusion is partly inhibited by reduction of serosal pH, luminal HCO3- secretion is reduced. Basolateral H+ secretion occurs in exchange for Na+ via an ethylisopropylamilorideinsensitive mechanism and is ultimately fueled by the activity of the basolateral Na+-K+-ATPase. Fluid absorption by the toadfish intestine to oppose diffusive water loss to the concentrated marine environment is accompanied by a substantial basolateral H+ extrusion, intimately linking osmoregulation and acid-base balance.