Early biochemical and histological changes during hyperbaric or normobaric reoxygenation after in vitro ischaemia in primary corticoencephalic cell cultures of rats.

In a first series of experiments, the morphological changes of corticoencephalic cells by ischaemia were determined by staining with celestine blue-acid fuchsin in order to classify cells as intact, dark basophilic (supposedly reversibly injured) and preacidophilic or acidophilic (profoundly injured). Hypoxia and glucose-deprivation (in vitro ischaemia) markedly decreased the number of intact cells and correspondingly increased the number of both reversibly and profoundly damaged cells. The morphological characteristics indicated a partial recovery during reoxygenation either in the absence or presence of glucose and irrespective of whether normobaric or hyperbaric oxygen was used. In a second series of experiments, nucleoside triphosphate and diphosphate levels were determined in corticoencephalic cultures by high-performance liquid chromatography. Hypoxia in combination with glucose-deficiency markedly decreased the ATP:ADP, GTP:GDP and UTP:UDP ratios. A still larger fall of these ratios was observed both after normobaric and hyperbaric reoxygenation. In contrast, both normobaric and hyperbaric reoxygenation in the presence of glucose led to an almost complete recovery near the control normoxic values. In conclusion, the histological changes were not adequately reflected by changes in the nucleoside triphosphate:diphosphate ratios and, in addition, hyperbaric oxygen had neither favourable nor unfavourable effects on the early morphological and functional restitution of ischaemically damaged cells under the conditions of the present study.