PENTOXIFYLLINE INCREASES RIF-1 TUMOR PO(2) IN A MANNER COMPATIBLE WITH ITS ABILITY TO INCREASE RELATIVE TUMOR PERFUSION

The time course and dose response of 600 mm(3) subcutaneous RIF-1 tumo urs to pentoxifylline was measured in terms of relative tumour perfusi on, assayed by Rb-86 extraction, and pO(2) distribution measured by th e Eppendorf histograph. Both perfusion and pO(2) distribution were max imally increased by 20 mg/kg pentoxifylline 15 min after administratio n, perfusion to 141 +/- 15% (2 SE) of control, and median pO(2) from 3 to 15 mmHg, with the percentage of values < 2.5 mmHg falling from 44 +/- 8% to 22 +/- 7%. Fifteen minutes after administration the pO(2) in creases were linearly dose-dependent up to 20 mg/kg. Correlation coeff icients for perfusion data with the percentages of low values were, fo r time course and dose response data respectively, 0.76 and 0.84 for m edian pO(2), 0.84 and 0.97 for percentage < 2.5 mmHg and 0.81 and 0.87 for percentage < 10 mmHg, The data show good correlation between chan ges in perfusion and pO(2) distribution parameters, with better correl ation for percentage of low values than for median pO(2).