Acute Recovery and Delayed Changes in Tissue Following Transient Cerebral Hypoxia-Ischemia:Impedance,Electron Microscopy and MR Imaging Studies in Rats

Abstract

A transient episode of cerebral hypoxia-ischemia will produce transient biochemical and cellular changes that may be followed by a delayed cell death. Magnetic resonance (MR) imaging techniques have demonstrated that despite a normalization of images post reperfusion, a secondary or delayed return of hyperintense areas in the T2 and diffusion weighted (DW) images can appear several hours after the end of the hypoxic-ischemic insult [1, 2]. Reductions in extracellular space and cell swelling are known to occur during ischemia and are considered to underly some of these MR imaging changes. How well the extracellular space changes recover upon reperfusion is not known. Presently, we examine the pre, during and post hypoxic-ischemic changes in extracellular space in rats at two different ages because hypoxic-ischemic MR-imaging changes differ between them [2].