Fig. 3. Changes in hummingbird uncoupling protein (HmUCP) mRNA levels during torpor and rewarming. (A) Profile of the rate of oxygen consumption of a representative specimen of Eupetomena macroura during euthermy, torpor and rewarming. Body temperatures were 33-40 °C and 15-23 °C during euthermy and torpor, respectively. (B) Northern blot of total RNA (probed with [-³²P]dCTP-labelled HmUCP coding region) obtained from heart and pectoral (wing) muscle of birds killed at the indicated times of the torpor/rewarming cycle. E, euthermy; T, torpor; R, rewarming. The ribosomal (18S) RNA was stained with Methylene Blue. (C) Ratio between HmUCP mRNA and ribosomal RNA obtained after densitometry. Values are the mean + range. Two animals were used per activity state. ^*P<0.05 compared with euthermy (E); ^**P0.05 compared with rewarming (R) (ANOVA). Reproduced from Vianna et al. (2001) with permission from the American Physiological Society.