Dk. Kelleher et al., LOCALIZED HYPOTHERMIA - IMPACT ON OXYGENATION, MICROREGIONAL PERFUSION, METABOLIC AND BIOENERGETIC STATUS OF SUBCUTANEOUS RAT-TUMORS, British Journal of Cancer, 78(1), 1998, pp. 56-61
The effect of localized hypothermia on microcirculatory and metabolic
parameters in s.c. DS sarcomas on the hind foot dorsum of Sprague-Dawl
ey rats was investigated. Tumours were cooled by superfusion of the tu
mour surface with cooled saline solution to 25 degrees C or 15 degrees
C. Control tumours remained at 35 degrees C. These temperatures were
maintained for 30 min. In tumour oxygenation measurements, hypothermia
at 25 degrees C and 15 degrees C caused progressive decreases in the
size of the fraction of pO(2) measurements between 0 and 2.5 mmHg toge
ther with a reduction in pO(2) variability. No significant changes in
median or mean pO(2) or in the fraction of pO(2) measurements between
0 and 5 mmHg, and 0 and 10 mmHg were observed. Using laser Doppler flo
wmetry, red blood cell flux was found to decrease significantly upon 2
5 degrees C or 15 degrees C hypothermia treatment to 67% and 37% of st
arting values respectively, whereas no significant changes were seen i
n control tumours over the whole observation period. Viscosity was mea
sured in blood and plasma samples over a range of temperatures and was
found to increase with decreasing temperature. Assessment of tumour g
lucose levels showed an increased concentration of glucose following 1
5 degrees C hypothermia, an observation consistent with a 'slowing dow
n' of glycolysis. No changes in lactate or adenylate phosphate levels
were observed. As a way of improving tumour oxygenation, localized hyp
othermia may therefore be a useful means of radiosensitization.