Ionic shift in cerebral ischemia

Electrolyte and water contents were measured in gerbil brain after unilateral cerebral ischemia. Increase of Na⁺ and water, and decrease of K⁺ occurred after an ischemic period of 30 minutes. However, these abnormalities disappeared within 3 hours. When the ischemic period was extended to 3 hours, the abnormalities observed after ischemia for 30 minutes were again encountered, but more significant alterations occurred immediately after re-establishment of blood flow. In addition to more pronounced increase of Na⁺ and decrease of K⁺, Ca²⁺ became significantly elevated after recirculation for 15 minutes and progressively increased during recirculation for 3 hours. The steady rise of Ca²⁺ appears to be related to the irreversibility of cerebral ischemia.