RAPID CORRECTION OF SEVERE HYPONATREMIA IN THE RAT - HISTOPATHOLOGICAL CHANGES IN THE BRAIN

The effects of rapid correction of severe hyponatremia (serum Na < 120 meq/l) either to mildly hyponatremic levels (serum Na = 130 meq/l) or to normonatremic levels (serum Na = 150 meq/l) on the brain histology of rats were examined. In group I, 13% of the rats revealed brain lesions following correction to mildly hyponatremic levels by the administration of 855 mM NaCl. All the rats (100%) in group II had brain lesions following correction to normonatremic levels by 24 h of water restriction. Similarly, all the rats in group III showed brain lesions following correction to normonatremic levels by the administration of 855 mM NaCl. Severe hyponatremia by itself did not cause any brain lesions in another group. Rapid correction of severe hyponatremia to mildly hyponatremic levels by the administration of 855 mM NaCl does not cause significant brain lesions. Rapid correction to normonatremic levels either by water restriction or by the administration of 855 mM NaCl results in significant brain lesions.