Volume regulation of muscle cells in the carp Cyprinus carpio in response to hypernatremia.

BACKGROUND: Hypernatremia supports the movement of water from the intracellular to the intercellular space. This shift leads to cells shrinkage and disruption of intracellular processes, representing risk factors of morbidity and mortality in clinical circumstances. On the other hand, hypernatremia triggers protective mechanisms that counteract damage of cells.

OBJECTIVES: To determine in experiments in vivo the ranges of sodium content regulation in the blood plasma of carp characterizing the norm and hypernatremia. To identify the patterns volume regulation of skeletal muscles cells in response to hypernatremia.

METHODS: Carps were acclimating for 3 weeks to a different salinity in the range of 0-12 g/L. In the plasma and muscle tissue the concentration of sodium, potassium, calcium and magnesium was determined by the method of flame spectrophotometry. Water content in the muscles has been additionally determined.

RESULTS: Carps acclimated in the salinity range of 0-6 g/L, maintained the concentration of sodium in blood plasma within of the range of 129-135 mmol/L (normonatremia). In the salinity zone of 6-12 g/L concentration of sodium in the blood plasma of fish has increased to 207 mmol/L (hypernatremia). Hypernatremia was causing the increase of the sodium, potassium, calcium and magnesium content in carp muscles and the drop of water level.

CONCLUSIONS: Muscle tissue of carp adapts to hypernatremia by means of increasing inorganic ions by 70.8 % and organic osmolytes by 29.2 % (Fig. 2, Ref. 51).