The cooling tube: A novel small animal model of systemic hypothermia in awake Syrian Golden Hamsters ( mesocricetus auratus )

Abstract

Hypothermia is increasingly used as a therapeutic strategy in a diversity of clinical scenarios. Its impact on mammalian physiology, particularly on the microcirculatory changes of critical organ systems, are, however, incompletely understood. Close examination of the literature reveals a marked paucity of small animal models of rapid systemic hypothermia. All published models introduce important microvascular confounders by investigating either local cooling processes or using anaesthetised animals. Here we present the first rapid systemic hypothermia model in an awake hamster. We developed a waterstream cooled copper tube system for standardized systemic temperature control. With this novel system core body temperature (T _c ) in 14 awake animals could be precisely stabilised at temperatures of 30°C and 18°C (7 animals, respectively) within 10–20 min. Rewarming was achieved over 10–15 min. Tolerance of the procedure was excellent. Hamsters did not show any behavioural changes in the mild hypothermia group. In the deep hypothermia group 6 of 7 animals regained normal behaviour within 2–11 hs. As hypothermia was induced in dorsal skinfold chamber bearing animals this model seems suitable for investigation of microcirculatory purposes.

Advantages over previously established experimental hypothermia models are significant. Amongst these, the possibility of visualization of microcirculation, the lack of microcirculation confounding factors such as anaesthetic drugs, the ability for precise T _c control and rapid induction of hypothermia are prominent.