HETEBOTHEBMY IN HOMEOTHEPMS 



because of its lowthermalconductivity,youwillhave a considerable 

 delay in detection of vasodilation. We have used the mercury strain 

 gauge, which you can place on the finger and which makes plethysmo- 

 graphic measurements by using either the olume pulse or the meas- 

 urement of blood flow but does not interfere with the exposure of the 

 finger to the environment. And here we have a very sensitive meas- 

 ure of the most subtle changes in mscular responses. Yet, despite 

 this we have failed to detect any evidence in favor of a local adapta- 

 tion to cold insofar as the CIVD response is concerned. 



FOLK: I would like to ask Dr. Johansen to comment again on 

 his work with huskies. As I understand it they showed high body tem- 

 peratures after being on the trail. If you are talking about some 

 other animal we might find evidence of cross-acclimatization, but 

 if I understand it correctly, the husky does not show cold acclima- 

 tization. Is it possible that there might be heat acclimatization? 



JOHANSEN: My studies on the exercising of huskies were 

 essentially not complete in the sense that I studied all the factors 

 tnvohed in thermobalance. I did not measure superficial tempera- 

 tures, for example. I did find, however, that training lowers to some 

 extent the great increase in temperature that is seen after intense 

 exercise. I do not know if this will hold up statistically, but I do 

 think that the effector systems for heat loss in the husky, the wolf, 

 the fox, and a number of other semi- large arctic mammals are not 

 effective enough to give a steady statethermalbalance at high levels 

 of exercise. There seems to be an inevitable accumulation of heat.* 



MORRISON: What was the ambient temperature when you were 

 running those huskies? 



JOHANSEN: From 30° C to 40° C below zero. 



MORRISON: We ran some similar studies with huskies, and 

 in two sets of experiments of about an hour each we did not get any 



♦Rapid or slow, this heat accumulation is probably related to the whole problem 

 of fatigue. 



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