IS THE NAKED MOLE-RAT HETEROCEPHALUS-GLABER AN ENDOTHERMIC YET POIKILOTHERMIC MAMMAL

1. Thermoregulatory changes with ambient temperature (T(a)) were monitored in Heterocephalus glaber between 12 and 37-degrees-C. 2. At all T(a)s monitored, body temperature (T(b)) was directly proportional to T(a) (T(b) = 0.568 + 1.016 T(a)). 3. Below T(a) 29-degrees-C, VO2 varied in a typically poikilothermic pattern, whereas above 29-degrees-C, VO2 followed a typically endothermic pattern. 4. At T(a)s between 31 and 34-degrees-C, VO2 was minimal (1.00 +/- 0.09 ml/g/h), skin temperature was 1.8 +/- 0.6-degrees-C lower than T(b) and evaporative water loss accounted for 173.7 +/- 51.0% of the metabolic heat produced. 5. The high rates of heat transfer are such that individual naked mole-rats cannot regulate T(b) over the entire range of measured T(a)s and, as such, are poikilothermic mammals.