HIBERNATION IN MAMMALS— LYMAN and CIL'\TFI1<:LD 



600^ 



103 



500 



400 



Rate 300 



200 



100 



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Q I ' I I I I i I I I I I I I I I I I I I I I I I I I i I I I I ] I I I 



10 20 30 40 



T° C 

 Fig. 15. — Composite graph of tlie heart rates/min. of 6 hamsters arousing from hiljernation, 

 plotted against their cheek-pouch temperatures. Linear coordinates. 



reported in the literattire were due to errors or omissions in experimental 



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'S The problem of the linear relationship of heart rate to temperature and also oxygen con- 

 sumption to temperature in the waking hibernator lias been explored further by C. Kayser, 

 AI. L. Rietsch and M. A. Lucot (Arch. d. Sci. Physiologiques 8: 155, 1955). Although their 'data 

 do not fit the Arrhenius equation over the whole temperature range of 5° to 35° C, they feel that 

 the plot actually falls into a series of three straight lines if the waking process is considered as 

 three separate steps. With the complicated changes described below, which take place during 

 arousal from hibernation, it would seem most unlikely that cither heart rate or oxygen consump- 

 tion would fit the Arrhenius equation. This conclusion is fortified by the observation of Daw-e and 

 Morrison (Am. Heart J. 49: 367, 1955) that the heart rate-body temperature function is totally 

 different in arousal than during the process of entering hibernation. 



G. Biorck and B. Johansson (Acta Physiol. Scand. 34:257, 1955), found a steeper sloi>e in 

 the plot of heart rate against temperature from 15° to 22°. It may be that one source of dis- 

 crepancies in measurements of the relationships between heart rate and temperature in the arous- 

 ing hibernator is that in some cases (Endres, et al., Biorck, et al.), the animal was warmed 

 with heat from external sources. Smce the control of circulation is such an important phase of 

 the process of arousal, (see below), it seems likely that external heat might affect the heart rate. 



