A Simplified Hot-Plate Apparatus for Evaluation of Analgesic Effect

1. A. simple hot-plate apparatus, with comparatively good accuracy in the control of temperature, chiefly composed of a circular lead plate embedded with nicrome-wire heater was devised in order to improve the complications and inconveniences of the hot-plate apparatus used to date in algesimetric determination with mice. 2. The reaction times measured with this hot-plate maintained at 55°C with 500 normal mice showed an average of 9.96 ± 1.58 seconds and about 90% of the total mice exhibited reaction time of 7-13 seconds. With animals showing reaction time within this range, the daily mean reaction time did not vary with measurement once a day for consecutive days and the effect of drugs with comparatively weak analgesic effect was well reproduced with small number examples, such as 12 mice to a group.