CHOROID-PLEXUS ELECTROLYTES AND ULTRASTRUCTURE FOLLOWING TRANSIENT FOREBRAIN ISCHEMIA

A temporal profile of lateral and fourth ventricle rat choroid plexus (LVCP and 4VCP, respectively) tissue injury and recovery was determined using alterations in K, Na, and H2O content and ultrastructure after 10 min of transient forebrain ischemia (TFI). At 0.5 h postischemia the LVCP displayed a maximum reduction in K content by 32% and a significant increase in Na content by 85% and H2O content by 22%. LVCP tissue K, Na, and H2O content returned to sham values by 24 h postischemia. Ultrastructural changes appeared more severe between 0.5 and 12 h postischemia, whereas by 24 h, normal ultrastructure was restored. Elevations in 4VCP tissue Na (P < 0.05) and H2O content, which were less than those in LVCP, gradually reached a maximum by 24 h compared with sham. No change in 4VCP tissue ultrastructure was observed. These results indicate that the LVCP tissue is more vulnerable than 4VCP in the bilateral carotid artery occlusion model but that it recovers in a timely manner after TFI. Furthermore, the ability of the LVCP tissue to rapidly recover suggests its functional importance in helping to restore brain homeostasis.