Comments On: Changes in PO₂ and Ion Fluxes in Cerebral Hypoxia-Ischemia

Abstract

The demonstration of inhomogeneous damage in shock relative to hypoxia is consistent with the hypothesis that inhomogeneous perfusion is present and may be responsible for many of the graded biochemical changes noted in ischemia. In our laboratory we have also noted marked inhomogeneity in ischemic lesions as was mentioned earlier by Dr. Welsh. (Fig. lb) In hypoxic animals the lesion demonstrated by frozen tissue fluorescence is likely to be more homogeneous as can be seen in Figure la. However, even in the hypoxic insult, there is usually evidence of some metabolic inhomogeneity. This is especially evident when there is slight oligemia associated with hypoxia. (Fig. 1c) I think it is important to keep this finding in mind when trying to interpret biochemical changes in either hypoxic or ischemic lesions. That is, when a graded change in one of the metabolic parameters is noted, it may be due to a slight diffuse or to a marked focal variation. This problem has, of course, been recognized at the subcellular level for some time.