Water metabolism in rats under hypokinesia and during readaptation

It has been suggested that hypokinesia (diminished muscular activity)* may induce substantial changes in water metabolism in animal tissues. Thus, the objective of this study was to try to determine water metabolism reactions in 115 rats weighing 156-168 g under hypokinesia (HK) of 60-days and during the readaptation period (RP) of 15-days. All of the examined rats were divided into experimental and control groups. The experimental group of rats were subjected to pure HK, that is, without the use of any preventive measures, and the control group placed under ordinary vivarium conditions and served as control. For the simulation of the hypokinetic effect the experimental group of rats were kept in small individual cages made of plexiglas, which restricted their movements in all directions without hindering feed and water intake. Both groups of rats received water and salt supplements. Fluid intake and elimination, sodium and potassium content in urine and blood, hematocrit index and water content in blood were measured. Under hypokinesia a marked diuresis and electrolyte excretion as well as changes in blood electrolyte composition were demonstrated. Hematocritic index and blood water content changed unreliable. During the readaptation period diuresis and mineral excretion diminished substantially. It was concluded that exposure to hypokinesia induced significant changes in water metabolism of rats, regardless of the additional intake of water and salts.