Hyperthermia-induced alteration in erythrocyte velocity in tumors

The effect of a hyperthermic treatment on the microcirculation of the experimental tumor Rhabdomyosarcoma BA1112 was investigated. The tumor was grown in 'sandwich' chambers in the rat skin. The erythrocyte velocity in selected capillaries was used to assess changes in the microcirculation. For this purpose, a simplified comparative method in which the (adjusted) velocity of a train of light dots indicated the velocity in the capillary was employed. During hyperthermic treatment (n = 16) consisting of an exposure of 180 minutes at 43 degrees C, it was apparent that a slight increase in erythrocyte velocity first occurred. This was followed, however, by a decrease and eventually a complete standstill.