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

摘要: 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 poor water external NO−2 concentrated the blood plasma until at approximately same molar concentration as haemoglobin (about 8 mmol) and this point has been oxidized methaemoglobin being a contributory cause death. Two theories are advanced account for blood. first supposes that gills impermeable but allow its conjugate acid nitrous (HNO2) diffuse into where dissociates according pH value. Thus will accumulate if higher value than water. second uptake mechanism freshwater gill an affinity accounts fact entry suppressed when present significant amounts. The results also suggest behave similarly diffusing ions. diffusion seawater fish loaded occurs rate corresponding fluxes. Nitrite loss thought be mainly although there some evidence active extrusion having weak nitrite.