Recent studies have maintained that cytochrome c release from mitochondria into the cytosol is involved in the death of CAI neurons after global ischemia (155). However, such results are not clearly interpretable. The change might not reflect events occurring in neurons specifically, because brain tissue was used to prepare soluble extracts. The change could reflect release or abnormal import of cytochrome c into mitochondria due to subcellular damage, and, if it is release, it could be non-physiological and spontaneous due to mitochondrial disruption rather than physiologically regulated release.