THE RELATIONSHIP BETWEEN OXYGEN UPTAKE AND ION LOSS IN FISH FROM DIVERSE HABITATS
THE RELATIONSHIP BETWEEN OXYGEN UPTAKE AND ION LOSS IN FISH FROM DIVERSE HABITATS
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不同栖息地的鱼类摄氧量与离子损失之间的关系
DOI：
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发表时间：
1994
影响因子：
2.8
通讯作者：
D. G. McDonald
中科院分区：
文献类型：
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作者：
R. J. González;D. G. McDonald
最近对淡水鱼的O2摄取（M（dot）O2）和扩散性钠丢失（JNaout）之间关系的研究表明，力竭运动后的Na+丢失超过了基于M（dot）O2的预期，这可能是由于细胞旁紧密连接（扩散性离子丢失的主要部位）和/或肾小球型滤过的变形引起的板层压增加。在本研究中，在不同的栖息地的9种鱼类的这种关系的检查支持这个模型。在常规条件下，Na+损失率每单位消耗的O2（称为离子/气体比或IGR）是相似的，在所有测试的物种，平均61.6 pmol Na+ nmol-1 O2。力竭运动后，每种动物的IGR相对于其常规水平（运动后IGR/常规IGR）增加的程度与M（dot）O2的相对上升呈指数关系，即O2摄取率越高，离子损失越大。进一步的分析表明，虽然自然活性物种的M（点）O2的增加比例最低，但由于其高的常规速率，它们具有最高的运动后O2摄取率。事实上，运动后IGR和M（dot）O2之间存在负相关性，即M（dot）O2值较低的物种比M（dot）O2值较高的物种每摩尔O2损失更多的Na+。因此，天然活性物种，如常见的和金色的闪光，能够实现更高的O2吸收率，同时避免高速率的离子损失。令人惊讶的是，带状翻车鱼、黄鲈鱼和小嘴鲈鱼等物种并没有限制与运动相关的离子损失，尽管它们显然有能力这样做。他们表现出很强的能力，以限制离子损失所造成的短暂的渗透冲击和暴露于软水（这两个扭曲紧密连接）。
A recent examination of the relationship between O2 uptake (M(dot)O2) and diffusive sodium loss (JNaout) in a freshwater fish showed that Na+ losses after exhaustive exercise exceeded those expected on the basis of M(dot)O2, probably due to distortion of the paracellular tight junctions (the primary site of diffusive ion loss) and/or glomerular-type filtration caused by increased lamellar pressure. In the present study, an examination of this relationship in nine species of fish from diverse habitats supports this model. Under routine conditions, the rate of Na+ loss per unit of O2 consumed (termed the ion/gas ratio or IGR) was similar in all the species tested, averaging 61.6 pmol Na+ nmol-1 O2. After exhaustive exercise, the degree to which the IGR of each species increased relative to its routine levels (post-exercise IGR/routine IGR) was exponentially related to the relative rise in M(dot)O2, i.e. greater rates of O2 uptake led to even greater ion losses. Further analysis revealed that, although naturally active species had the lowest proportionate increase in M(dot)O2, by virtue of their high routine rates, they had the highest post-exercise rates of O2 uptake. In fact, there was an inverse correlation between post-exercise IGR and M(dot)O2, i.e. species with low M(dot)O2 values lost more Na+ per mole of O2 taken up than did species with high ones. Thus, naturally active species, such as the common and golden shiner, were able to achieve higher rates of O2 uptake while avoiding high rates of ion loss. Surprisingly, species such as banded sunfish, yellow perch and smallmouth bass did not limit ion loss associated with exercise despite their apparent ability to do so. They demonstrated a strong ability to limit ion losses caused by a brief osmotic shock and by exposure to soft water (both of which distort tight junctions).