title: Localized hypothermia: impact on oxygenation, microregional perfusion, metabolic and bioenergetic status of subcutaneous rat tumours.
abstract: The effect of localized hypothermia on microcirculatory and metabolic parameters in s.c. DS sarcomas on the hind foot dorsum of Sprague-Dawley rats was investigated. Tumours were cooled by superfusion of the tumour 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 pO2 measurements between 0 and 2.5 mmHg together with a reduction in pO2 variability. No significant changes in median or mean pO2 or in the fraction of pO2 measurements between 0 and 5 mmHg, and 0 and 10 mmHg were observed. Using laser Doppler flowmetry, red blood cell flux was found to decrease significantly upon 25 degrees C or 15 degrees C hypothermia treatment to 67% and 37% of starting values respectively, whereas no significant changes were seen in control tumours over the whole observation period. Viscosity was measured in blood and plasma samples over a range of temperatures and was found to increase with decreasing temperature. Assessment of tumour glucose levels showed an increased concentration of glucose following 15 degrees C hypothermia, an observation consistent with a 'slowing down' of glycolysis. No changes in lactate or adenylate phosphate levels were observed. As a way of improving tumour oxygenation, localized hypothermia may therefore be a useful means of radiosensitization.
authors.affiliation: Institute of Physiology and Pathophysiology, University of Mainz, Germany.
authors.forename: D K
authors.initials: DK
authors.lastname: Kelleher
authors.forename: C
authors.initials: C
authors.lastname: Nauth
authors.forename: O
authors.initials: O
authors.lastname: Thews
authors.forename: W
authors.initials: W
authors.lastname: Krueger
authors.forename: P
authors.initials: P
authors.lastname: Vaupel
mesh_terms: D000818:Animals; D001809:Blood Viscosity; D007036:Hypothermia, Induced; D017078:Laser-Doppler Flowmetry; D008297:Male; D008833:Microcirculation; D010101:Oxygen Consumption; D051381:Rats; D017207:Rats, Sprague-Dawley; D012513:Sarcoma, Experimental / Q000097:blood / Q000098:blood supply / Q000378:metabolism / Q000628:therapy; D012878:Skin Neoplasms / Q000097:blood / Q000098:blood supply / Q000378:metabolism / Q000628:therapy