This study was designed to test the hypothesis that vasodilator drugs can enhance selective heating of solid tumors by producing a favorable redistribution of blood flow between tumor and normal tissues. Subcutaneous transmissible venereal tumor implants were heated by inductive diathermy using Helmholtz coils in 8 dogs. The temperature rise in tumor and adjacent muscle was measured before and after giving hydralazine (0.5 mg/kg i.v.). Blood flow to the tumors and underlying muscle was measured with radioactive tracer microspheres. Before hydralazine treatment mean muscle blood flow was about one-third tumor blood flow (0.11 0.02 vs. 0.28 0.09 ml/min/g), and tumor and normal muscle temperatures were not significantly different (40.0 0.6 vs. 39.7 0.l oC). After hydralazine tumor blood flow decreased and muscle blood flow increased in every dog, and selective heating of the tumors became possible. Muscle blood flow averaged 0.67 0.13 ml/min/g, 17 times greater than tumor blood flow, which decreased to 0.04 0.02 ml/min/g. Core tumor temperature was 48.0 0.9 vs. 38.5 0.5 oC for underlying muscle. Blood pressure was maintained at 80 5.7 mmHg. These results demonstrate that adjuvant treatment with vasodilators is a promising technique to increase the temperature difference between tumors and surrounding normal tissues during local heat therapy.
blood flow, heat, hyperthermia, regression, therapeutic ratio, treatment, tumor
Date of this Version
Voorhees, William D. III and Babbs, Charles F., "Hydralazine-enhanced Selective Heating of Transmissible Venereal Tumor Implants in Dogs" (1982). Weldon School of Biomedical Engineering Faculty Publications. Paper 119.