Figure 8.

(A) Photograph of the tail heating. The heat source was attached to the tail, and a voltage (35 V) was applied to the coil. The heat source was a tubiform coil of wire (50 turns) covered with a thin film made of acrylic resin. The whole aspect of the heat source looked like a plastic tube with an 8-mm inside diameter and a 20-mm length. Half of the inside was the effective electric heating surface. Following heating of the tail, rats whisked their tail (tail flick reflex) and bit the heat source when the tail was unable to be removed from heating by tail flick. The arrow points to the heat source. (B) An example of changes in the skin temperature of the tail after the heating was begun. In this case, the skin temperature of the tail before heating was 30.1°C. After heating was begun, the skin temperature of the tail almost linearly increased to 74.0°C at 10 s. (C) The relation between the skin temperature of the tail and the time from the beginning of tail heating. Eleven points were obtained from 11 untreated rats. Note that a high correlation (R² = 0.99) was observed between the skin temperature of the tail and the time from the beginning of tail heating (Tsuruoka et al., 2011).