Uptake and loss of nitrite from the blood of rainbow trout, Salmo gairdneri Richardson, and Atlantic salmon, Salmo salar L. in fresh water and in dilute sea water
Uptake and loss of nitrite from the blood of rainbow trout, Salmo gairdneri Richardson, and Atlantic salmon, Salmo salar L. in fresh water and in dilute sea water
复制标题
淡水和稀海水中虹鳟鱼（Salmo gairdneri Richardson）和大西洋鲑鱼（Salmo salar L.）血液中亚硝酸盐的吸收和损失
DOI：
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发表时间：
1983
期刊：
影响因子：
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通讯作者：
R. Bath
中科院分区：
文献类型：
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作者：
F. Eddy;P. Kunzlik;R. Bath
亚硝酸盐(NO−2)对鲑鱼的急性毒性被氯离子(Cl−)强烈改善，使其在大多数淡水中几乎是无害的，但Cl−含量较低的淡水除外。在Cl-−贫乏的淡水中，NO-−-2在血浆中聚集，直到它与血红蛋白的摩尔浓度大致相同(约8 mmo1)，此时大部分的血红蛋白已被氧化成高铁血红蛋白，这是导致死亡的原因之一。
提出了两种理论来解释血液中的NO−2浓度。第一种假设是，鳃对NO−2是不可渗透的，但允许其共轭亚硝酸(HNO2)扩散到血液中，在那里根据血液的pH值进行解离。因此，如果血浆的pH值高于水，则不会有−-2在血浆中积累。第二种假设认为淡水鳃中的Cl-−摄取机制与NO-−-2有亲和力，并解释了当外部Cl-−大量存在时，不会有−进入血液的事实。
结果还表明，NO-−-2和Cl-−的行为类似于扩散离子。因此，没有−2进入海水鱼的血液和从没有−2的淡水鱼的血液中扩散的速度与相应的Cl−通量大致相同。海水鱼的亚硝酸盐损失被认为主要是通过扩散，尽管有一些证据表明，活性的Cl-−挤出机制对亚硝酸盐的亲和力很弱。
The acute toxicity of nitrite (NO−2) to salmonids is strongly ameliorated by chloride (Cl−) ions rendering it almost harmless in most fresh waters apart from those with low Cl− content. In Cl− poor fresh water external NO−2 is concentrated in the blood plasma until it is at approximately the same molar concentration as haemoglobin (about 8 mmol) and at this point most of the haemoglobin has been oxidized to methaemoglobin this being a contributory cause of death.
Two theories are advanced to account for NO−2 concentration in the blood. The first supposes that gills are impermeable to NO−2 but allow its conjugate acid nitrous acid (HNO2) to diffuse into the blood where it dissociates according to the blood pH value. Thus NO−2 will accumulate in the blood plasma if it has a higher pH value than the water. The second supposes that the Cl− uptake mechanism in the freshwater gill has an affinity for NO−2 and accounts for the fact that NO−2 entry to the blood is suppressed when external Cl− is present in significant amounts.
The results also suggest that NO−2 and Cl− behave similarly as diffusing ions. Thus NO−2 diffusion into the blood of seawater fish and from the blood of NO−2 loaded freshwater fish occurs at approximately the same rate as the corresponding Cl− fluxes. Nitrite loss from seawater fish is thought to be mainly by diffusion although there is some evidence for the active Cl− extrusion mechanism having a weak affinity for nitrite.