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Biology | Systems and Integrative Physiology | Zoology


1. Arrest temperatures and Q10 values for extensor digitorum longus (EDL), soleus, trabecula, and jejunum muscle twitch strength, contraction time, and 0.5 relaxation time were calculated for a deep torpor hibernator, white-tailed prairie dog (WTPD) (Cynomys leucurus), a shallow torpor hibernator, black-tailed prairie dog (BTPD) (Cynomys ludovicianus), and a non-hibernator, lab rat (Rattus norvegicus) to test the hypothesis that tissue temperature tolerances limit the depth of expressed torpor.

2. There were no temperature tolerance differences between the tissues of the two species of hibernators. Both hibernating species had arrest temperatures and Q10 values more indicative of cold temperature tolerance than the lab rat in all tissues, with the exception of the soleus muscle.

3. These data imply that a limited cold tolerance of contractile tissue does not preclude a shallow torpor hibernator such as the black-tailed prairie dog from expressing deep torpor patterns. Other mechanisms, such as central neural control, are more likely to be important in determining the torpor strategy utilized by hibernating species.