Cerebral Water and Electrolytes

Abstract

Administration of fluid and vasopressin injection to rats induced within 24 to 48 hours a condition which can be considered as an experimental model of the syndrome of inappropriate secretion of antidiuretic hormone (ADH). Concurrently with hyponatremia and hypoosmolarity in serum, the changes in muscle consisted of a fall in sodium content and a decrease in percentage dry weight equivalent to 12% swelling. There was no loss of potassium from muscle. In contrast, in brain the decrease in sodium content was smaller, the tissue percentage dry weight decreased only slightly, indicating minimal swelling, and there was a significant net loss of potassium. It is suggested that neurological dysfunction associated with the syndrome of inappropriate secretion of ADH is unlikely to be due to cerebral edema but may be related to the decreased potassium content of brain tissue.

The Effects of Hyponatraemia and Subarachnoid Haemorrhage on the Cerebral Vasomotor Responses of the Rabbit

“…Changes in extracellular osmolarity, cell volume, and intracranial pressure may explain the adverse effects of hyponatraemia. Under normal circum stances, mammalian cells resist changes in extracel lular osmolarity by sacrificing absolute amounts of intracellular cations to preserve cell volume (Holli day et aI., 1968; Dila and Pappius, 1972;Katzman and Pappius, 1973;Rymer and Fishman, 1973). The time taken to effect these adjustments in the central nervous system is not known (Grantham and Lin shaw, 1984), but the gradual development of chronic hyponatraemia is usually tolerated without neurological disturbance, whereas rapid alterations in osmolarity result in the potentially fatal distur bances of water intoxication (Swanson and Iseri, 1958;Lipsmeyer and Ackerman, 1966;Arieff, 1986) and pontine myelinolysis (Sterns et aI., 1986;Lau reno and Karp, 1988).…”

Altered brain structure with preserved cortical motor activity after exertional hypohydration: a MRI study

“…Hence, it is postulated that the continuous exercise bout at a higher intensity in our study, coupled with thermal stress (end T re of~38.8°C), could have altered neural metabolism (49,58) and ion channel properties in the neurons (44). This could lead to changes in brain electrolyte levels (Na ϩ , K ϩ , Cl Ϫ , and Ca 2ϩ ), which modulate brain water content (20,43,52).…”