An open-loop model for investigating mammalian thermosensitivity

We have developed, and herein describe, a simple, open-loop model in the rat, in which both skin and hypothalamic temperatures can be modified and clamped. A water-perfused thermode was positioned in the abdomen to drive hypothalamic temperature, and a water-perfused jacket was used to clamp skin temperature. These permitted the independent control of hypothalamic and skin temperatures. The former could be altered between 35 and 41 °C whilst achieving an isothermal skin temperature clamp. Similarly, skin temperature could be modified between 22 and 42 °C whilst hypothalamic temperature was clamped. Maximal hypothalamic heating and cooling rates were: 0.75 and −2.04 °C h⁻¹ 100 g⁻¹. We are currently using this animal model to investigate how central thermosensitivity is affected via manipulations of hypothalamic cooling rates.