PO(2) MEASUREMENT IN MURINE TUMORS BY EPPENDORF HISTOGRAPH - CALIBRATION, REPRODUCIBILITY AND COMPARISON WITH DIAMOND-GENERAL DEVICE

The purpose of this study was to assess the usefulness of the Eppendor f 'Kistograph' as a device for measuring pO(2) in tumor and normal tis sues of the laboratory mouse. To determine the appropriate calibration and electrode condition, nitrogen bubbling time was changed, and the current during calibration was recorded. Reproducibility of pO(2) meas urements was tested in the series of human xenografts and murine isopl ants at different time points or in the same tumor in successive deter minations. pO(2) values obtained with the Eppendorf 'Histograph' were compared to those obtained with a manually controlled needle-type elec trode manufactured by the Diamond-General Company. The pO(2) values af ter 9 min of nitrogen bubbling were closer to the expected values than those after 3 min bubbling. The current during nitrogen bubbling in c alibration declined following the pO(2) measurement by an amount corre sponding to 0.8 mm Hg. Good reproducibility of pO(2) measurement was s hown in i) pO(2) values in the same cell line at different time points and ii) pO(2) values in two or three consecutive measurements in rela ted regions within the same tumor. The Eppendorf 'Histograph' and the Diamond-General device showed no significant differences in pO(2) dist ribution in either subcutaneous tissue or MCaIV tumors. In conclusion, results of the Eppendorf 'Histograph' were consistent and reproducibl e and were similar to those obtained by the Diamond-General set-up.