Effect of Acute Hyponatremia on Distribution of Water and Electrolytes in Various Tissues of the Rat

Abstract

Effects of acute hyponatremia, induced by intraperitoneal injection of isosomolar glucose solution, on electrolyte distribution in various tissues of rats have been studied and the following results were obtained. The hyponatremic procedure increases intracellular brain Na concentration, decreases K concentration and results in a slight but insignificant decrease in brain water. Muscle Na, K and Cl concentrations are decreased and Na space is smaller than Cl space; cellular hydration occurs. In the heart, Na and Cl spaces decrease, and there is no change in K concentration; cellular hydration also occurs. Bone responds with a marked loss of cellular Na and a slight decrease in Cl space; K concentration is unchanged; cellular hydration results from the procedure. Skin responds in still a different manner; Na and Cl spaces and K concentration are unchanged; however, dehydration rather than hydration occurs in skin. The implications of the various changes in tissue water and electrolytes associated with the acute hyponatremia are discussed and various tissues are postulated to be storage sites for Na and/or water. It is concluded that each tissue has its own intrinsic control of electrolyte and water metabolism.