Goldfish as a model for studying the effect of hypernatremia on blood plasma lipoproteins.

AIM: To evaluate the effect of hypernatremia on the organization of blood plasma high density lipoproteins (HDL) in goldfish; to compare the state of hypernatremia in fish and humans; to assess the possible risks and consequences of the effect of hypernatremia on human plasma lipoproteins. METHODS: The fish were acclimated for 20 days at a critical salinity of 11.5 g/L; after that the salt water was gradually "desalinated". The concentration of Na+ and the content of total water were determined in tissues, cells, and body fluids. The HDL organization was assessed by the number of apolipoprotein molecules per particle. The methods of flame spectrophotometry, electrophoresis and MALDI were used. RESULTS: In fresh water, the state of normonatremia was maintained in the fish body; at critical water salinity, the state of hypernatremia. Against the background of hypernatremia, the initial signs of muscle and erythrocyte dehydration appeared in fish, the total water content in the plasma did not change, and HDL disintegrated into small particles, which, upon restoration of normonatremia, were combined into the original large forms. CONCLUSION: In goldfish at the state of normonatremia, large forms of HDL are stable while at the state of hypernatremia, the small forms of HDL are stable. Under conditions of a hypertonic environment and plasma hypernatremia, the breakdown of HDL prevents the loss of water from the fish organism and reduces the threat of their dehydration. Human hypernatremia is characterized by plasma sodium levels comparable to that in goldfish, however accompanied by life-threatening metabolic changes. The results of this study may be useful for assessing the risks of HDL breakdown at hypernatremia and for the development of protocols for the treatment of pathological conditions in humans (Fig. 4, Ref. 45).

Shifted mineral ions transport in the mollusk Unio pictorum exposed to environmental concentrations of diclofenac.

Previous studies showed that diclofenac (DCF), when released in the environment, can be toxic to aquatic animals (fish and mollusks), affecting gills, which are the main organ of ionic regulation. This study focuses on detecting the effects of relevant environmental concentrations of DCF (0.1-1 µg L-1) on the transport of main mineral cations, i.e. sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg), by widely distributed freshwater bivalve mollusks Unio pictorum. After 96-h exposure to river aerated water at 25 °C with DCF concentrations of 0 (control), 0.1 (treatment I), and 1 µg L-1 (treatment II), the mollusks were transferred to deionized water, and daily (for 7 days) concentrations of these cations in the medium have been measured. Animals exposed to 1 µg L-1 DCF maintained the ionic balance between the organism and the diluted medium at a significantly higher level of Na, K, and Mg ions in water compared to the control and animals exposed to 0.1 µg L-1 DCF. At 0.1 µg L-1 DCF, the greater loss concerning the control (p < 0.05) was found only for Na ion. There were no differences in the dynamics of Ca ions between control and both treatments. This study showed that detectable environmental concentrations of DCF in natural waters can influence the transport of main cations required by freshwater animals to maintain their ionic balance, and the observed effect (elevated ion loss) is ion-specific and also dose-dependent.