Osmotic adaptation of the brains of scalded rats to chronic increase in plasma Na+. Effects of corticosteroids.
The effect of chronically increased plasma Na+ concentration, secondary to scalding, on the cerebral electrolyte and water content was studied in rats. In contrast to findings in acute hypernatremia, the water content of the brain remained constant in these experiments. Cerebral adjustment to chronic hypernatremia is supposed to be brought about by an increase of osmotically active solutes in the brain. Regression analyses of the Na+ concentration in brain water versus the plasma Na+ concentration indicate that accumulation of Na+ in brain tissue is responsible only for about 50--60% of the osmotic adjustment to increased plasma osmolality in chronic hypernatremia. Except for animals receiving prednisolone, the cerebral K+ content remained constant. Therefore, it may be concluded that except for this group, formation of idiogenic osmoles comprises about 40--50% of the extra osmolality in brain. Aldosterone and spirolactone do not seem to influence osmotic adaptation of the brain, or formation of idiogenic osmoles under these circumstances. Prednisolone, however, seems to enhance cerebral accumulation of K+ in chronic hypernatremia. This was concluded from the close correlation between the K+ concentration in brain water and the plasma Na+ concentration found in this group.
D000222:Adaptation, Physiological; D000305:Adrenal Cortex Hormones / Q000494:pharmacology*; D000818:Animals; D001834:Body Water / Q000378:metabolism; D001921:Brain / Q000503:physiopathology*; D001923:Brain Chemistry / Q000187:drug effects; D006955:Hypernatremia / Q000503:physiopathology*; D008297:Male; D009994:Osmolar Concentration; D011188:Potassium / Q000032:analysis; D051381:Rats; D012044:Regression Analysis; D012964:Sodium / Q000097:blood
D000305:Adrenal Cortex Hormones; D012964:Sodium; D011188:Potassium