| Abstract: | The gas phase partial pressure of O2 (PO2) overlying mouse keratinocyte cultures controls the rate of DNA synthesis of these cells by an undefined mechanism. In these studies, both PO2 and PCO2 tensions overlying primary cell cultures were varied within the physiologic range. The prostaglandin (PG) production of cells grown under several varying gas tensions was then determined using radioimmune assay. The cultures were grown under a PO2 of either 7.5% (physiologic for in vivo epidermis) or 21% (atmospheric; culture conditions and wound healing) for 5 days. The PCO2 was either 5 or 10%, 2 CO2 tensions routinely used in tissue culture studies. DNA synthesis was quantitated using [3H]dThd uptake into DNA and autoradiography. The PGE2 and PGF2 alpha syntheses by the cultures over specific time periods were determined. Changing the PO2 from 21 to 7.5% decreased the rate of DNA synthesis, while PG production remained constant. When the PCO2 was varied from 5 to 10%, keratinocyte DNA synthesis remained unchanged but PG production was markedly stimulated. The PCO2 effect on PG production was greatest at the highest oxygen tension. The data indicated that under this set of variables, PG production by keratinocytes is not directly related to the rate of DNA synthesis of the cells. Apparently the amount of oxygen in the gas phase can have a permissive effect on epidermal keratinocyte PG production. |
