HYPEROXIA INFLUENCES MESSENGER-RNA EXPRESSION OF CYTOKINES IN CULTURED HUMAN UMBILICAL VEIN ENDOTHELIAL-CELLS

High concentrations of oxygen, indispensable for the treatment of seve re hypoxemia from neonatal as well as adult respiratory distress syndr ome, increase the risk of oxygen toxicity. Biochemical mechanisms are lipid peroxidation, protein sulfhydryl oxidation, enzyme inactivation, and DNA damage. Recent reports suggest that cytokines might be involv ed in free radical injury as well as in adaptive response to hyperoxic injury. However, actual signal transduction pathways involving cytoki nes have not yet been clarified. In this study we exposed cultured hum an umbilical vein endothelial cells (HUVECs) to either ambient air or 100% oxygen, and compared for the rate of DNA synthesis [(H-3]thymidin e uptake) at different time points up to 72 h. After exposing the cell s to each treatment condition, we extracted RNA, constructed complemen tary DNA using reverse transcriptase, amplified the specific DNA segme nts of cytokines by polymerase chain reaction (PCR), and used the PCR products for gel electrophoresis to examine the bands which signified mRNA levels of corresponding cytokines. There was a significant decrea se in the rate of DNA synthesis as early as 24 h. The mRNA expression of IL-1 beta and TNFa seemed less influenced by hyperoxia, while IL-8 and TGF beta showed marked increase in mRNA levels at 6 h of 100% oxyg en exposure.