Effect of Hyperoxia on Superoxide Dismutase Content of Pig Pulmonary Artery and Aortic Endothelial Cells in Culture

Abstract

In order to test the hypothesis that pulmonary endothelial cells could be involved in the hyperoxia-induced increase in lung superoxide dismutase (SOD) content, we have measured total and KCN-insensitive SOD content of freshly isolated and cultured endothelial cells taken from the pulmonary artery and aorta of pigs. Freshly isolated and cultured pulmonary endothelial cells had a lower SOD content than aortic cells. Under culture conditions, both types of endothelial cells showed a marked increase in total SOD content, primarily due to the KCN-insensitive form of SOD. Since cultured fibroblasts and aortic myocytes did not exhibit the same phenomenon, this increase in total SOD content could not be attributed to culture conditions alone. Only cultured aortic endothelial cells increased both their total and KCN-insensitive SOD content when exposed to 95% O2-5% CO2 for 5 days following confluence. Exposure of aortic endothelial cells to hy-poxia (10% O2) for 5 days after confluence resulted in a slight decrease in their SOD content. These results suggest that the SOD content of endothelial cells is a function of their in vivo ambient O2 tension. Only endothelial cells that are potentially exposed to high O2 tensions can, when cultured, increase their SOD content in response to hyperoxia.