Electrolyte metabolic changes in rats during and after exposure to hypokinesia

The objective of this study was to determine fluid-electrolyte changes in male Wistar rats during 90 days of hypokinesia (decreased motor activity) and 15 days posthypokinesia. The animals were divided into two groups: rats subjected to hypokinesia served as experimental animals and rats placed under vivarium conditions served as control animals. The hypokinetic effect was carried out by keeping the experimental rats in small individual cages which restricted all their movements without hindering food and water intake. Determination was made of body weight, fluid consumed and eliminated in urine, sodium and potassium excretion in urine, concentrations of sodium and potassium in urine, the hematocrit level and water content in blood, and plasma concentration of sodium and potassium. During the experimental period body weight, water intake, urinary sodium and potassium content, and water content in blood decreased significantly, while electrolyte excretion in urine, plasma electrolyte concentration, hematocrit content and fluid excretion in urine increased significantly in the hypokinetic animals when compared with the control animals. During the initial seven days of the postexperimental period, water intake increased significantly while hematocrit level, water content in blood, and electrolyte plasma concentration remained markedly higher, and the fluid electrolyte excretion and electrolyte concentration thereof in urine decreased significantly. However, all these changes reverted back to the control level by the end of the post-experimental period. It was concluded that prolonged hypokinesia (HK) and the initial stages of post hypokinesia are associated with significant sodium and potassium changes and water consumption and elimination disturbances.