title: The levels and kinetics of oxygen tension detectable at the surface of human dermal fibroblast cultures.
abstract: Low oxygen tension has recently been shown to stimulate cell growth and clonal expansion, as well as synthesis and transcription of certain growth factors and extracellular matrix components. These results have been obtained by exposing cell cultures to a hypoxic environment. Using an oxygen probe, we have now studied how experimental conditions affect the oxygen tension detectable at the cell surface. Dissolved oxygen tension was directly related to the height of the medium above the cell surface (r = 0.8793, P = 0.021), but was constant when no cells were present in the flask (r = -0. 9732, P = 0.001). In both human dermal fibroblasts and NIH/3T3 cultures, oxygen tension decreased linearly as cell density increased (r = -0.835, P < 0.0001; r = -0.916, P < 0.0001, respectively). When human dermal fibroblasts were exposed to 2% O(2), maximum hypoxic levels (0 mmHg) were achieved within approximately 15 min, and the recovery time was within a similar time frame. The addition of rotenone, an inhibitor of cellular respiration, blocked this decrease in oxygen tension at the cell surface, suggesting that cellular consumption of oxygen is responsible for the decline. Finally, we examined the cell-surface oxygen tension in control and acutely wounded human skin equivalents (HSE), consisting of a keratinocyte layer over a type I collagen matrix containing fibroblasts. We found that oxygen tension dropped significantly (P < 0.0001) in acutely wounded areas of HSE as compared to unwounded areas of HSE and that this drop was prevented by the addition of mitomycin C. These results indicate that cell-surface oxygen tension is indirectly related to cell density, and that the amount of detectable oxygen at the cell surface is a function of cell density, the oxygen tension in the incubator, and increased cellular activity, as occurs after injury.
authors.affiliation: Department of Dermatology and Skin Surgery, Roger Williams Medical Center, Providence, Rhode Islandand 02908, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Tokuda
authors.forename: S
authors.initials: S
authors.lastname: Crane
authors.forename: Y
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: L
authors.initials: L
authors.lastname: Zhou
authors.forename: V
authors.initials: V
authors.lastname: Falanga
mesh_terms: D002452:Cell Count / Q000187:drug effects; D015687:Cell Hypoxia / Q000502:physiology; D019069:Cell Respiration / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003470:Culture Media; D004247:DNA / Q000096:biosynthesis; D020405:Dermis / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D007700:Kinetics; D008297:Male; D016685:Mitomycin / Q000494:pharmacology; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D009924:Organ Culture Techniques; D010100:Oxygen / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology*; D012402:Rotenone / Q000494:pharmacology; D013936:Thymidine / Q000493:pharmacokinetics; D014316:Tritium; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D003470:Culture Media; D019384:Nucleic Acid Synthesis Inhibitors; D014475:Uncoupling Agents; D012402:Rotenone; D014316:Tritium; D016685:Mitomycin; D004247:DNA; D010100:Oxygen; D013936:Thymidine