THE APPEARANCE OF OXIDOREDUCTASES IN HEALING FRACTURES

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Abstract
The activity of lactate, isocitrate, glucose‐6‐phosphate, succinate and lipoamide dehydrogenases, glutathione reductase, and cytochrome oxidase was demonstrated in the healing experimental fractures of mice. The animals were killed 1, 2, 4, 8, 10, 12 and 16 hours, and 1, 2 and 3 days after fracturing the right tibia. The subperiosteal osteocytes began to lose their oxidoreductase activity in ten hours. This decrease took place in a 200–500 μm deep central zone, in the immediate vicinity of the fracture line. In the same area necrosis could be histologically demonstrated in two days. In a peripheral zone, farther away from the fracture line, the oxidoreductase activity began to increase from the tenth post‐operative hour onwards in the osteoblasts and osteogenic cells of the inner periosteal layer. Lactate and lipoamide dehydrogenases showed the strongest, succinate and glucose‐6‐phosphate dehydrogenases the slightest intensification of activity. The proliferation of the periosteal cells after 16 hours contributed to the increase in oxidoreductase activity, remaining strong during the rest of the experimental period. Similar phenomena were observed in the endosteum, cytochrome oxidase showing the most intense reaction there. The decreasing enzyme activity in the central zone is an early sign of imminent necrosis. The initial increase in oxidoreductase activity in the peripheral zone represents an important part of the enzymatic response to injury, depicting the changing energy production in traumatized tissue.