Regional Accumulation of Calcium in Postischemic Rat Brain

Abstract

The regional concentrations of intravenously injected ⁴⁵Ca and total calcium were measured in rat brain during recovery from transient occlusion of the four major arteries to the brain. ⁴⁵Ca was injected at intervals after ischemia, and the regional distribution of ⁴⁵Ca was estimated by autoradiography. The ⁴⁵Ca appeared to enter the brain via the choroid plexus, labeling the paraventricular tissue at 1 h after the injection. Control brains had more ⁴⁵Ca in the gray matter compared to fiber-rich areas at 5 and 24 h, but within these regions the optical density was nearly uniform. The accumulation and retention of ⁴⁵Ca in postischemic brain were selective and time-dependent. The regional pattern of ⁴⁵Ca uptake correlated with the temporal progression of ischemic cell change. Infarction and preischemic hyperglycemia increased morphological damage, and increased the extent and distribution of ⁴⁵Ca accumulation. The rise in total calcium concentration appeared to be biphasic in irreversibly damaged tissue.