Oscillatory temperature response to constant power applied to canine muscle.

A previously unreported oscillatory temperature response has been observed in canine thigh muscle subjected to an abrupt application of a constant specific energy absorption rate (SAR). The power was applied to anesthetized dogs (stage 3 plane of anesthesia) using 2,450-MHz microwaves. Five types of responses have been identified that have occurrences depending on the maximal temperature produced by the applied power. In particular, for SAR values resulting in sufficiently high initial temperatures, self-sustaining temperature oscillations lasting over 4 h have been observed with amplitudes up to 7 degrees C. The temperature oscillations are believed to be caused by oscillations in the local blood perfusion rate.