Comparison of tumor and normal tissue oxygen tension measurements using OxyLite or microelectrodes in rodents
In this study we compare oxygen tension (Po2) histograms measured with O2 microelectrodes and a new optical Po2 measurement device, the OxyLite, in normal tissues (mouse spleen and thymus) and in tumors (R3230Ac in rats) (n = 5-6). The transient response to glucose infusion or 100% O2 breathing (hyperoxia) was also measured in tumors. Po2 histograms of spleen and thymus with the two devices were not different. The OxyLite tumor Po2 histogram, however, was left-shifted compared with the microelectrode (median Po2 1.0 vs. 4.0 mmHg, P = 0.016). Both probes responded to acute hyperglycemia with a mean increase of 3-6 mmHg, but the microelectrode change was not significant. The OxyLite consistently recorded large Po2 increases (∼28 mmHg) with hyperoxia, whereas the microelectrode response was variable. The OxyLite averages Po2 over an area that contains interstitial and vascular components, whereas the microelectrode measures a more local Po2. This study demonstrates the importance of considering the features of the measurement device when studying tissues with heterogeneous Po2 distributions (e.g., tumors).
Braun, RD; Lanzen, JL; Snyder, SA; Dewhirst, MW
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