IPVING 



significant difference between the heat dissipation to our digital 

 calorimeter of the control and locally cold conditioned digits. 



There is a possibility that this vasodilation, or relatively 

 reduced vasoconstriction, could be due to the destruction of the 

 components or functions in the finger that would allow for maxi- 

 mal vasoconstriction during immersion in the ice bath. That is, 

 the vasodilation we see developing in the locally cold conditioned 

 finger may be due to a destruction of vasoconstriction potential. 

 However, using anxiety again as a variable, we found that with our 

 subjects, all of whom were either medical or graduate students 

 and in whom it is very easy to induce anxiety, the induction of 

 anxiety by verbal suggestion at any point in the phase of vasodila- 

 tion brought the finger immediately to C, with a cooling pattern 

 similar to the initial vasoconstriction seen in the control experi- 

 ments. I do not feel, therefore, that the cold conditioned fingers 

 have lost the ability to vasoconstrict maximally. The altered CIVD 

 patterns appear to result from an adjustment in peripheral circula- 

 tory control rather than a simple destruction of function. 



EAGAN: I would like to point out that you have to be very care- 

 ful in using thermometry to deduce what is happening in the blood 

 vessels, but you cannot fool a calorimeter if you use exactly bal- 

 anced systems in testing the two fingers. In similar experiments 

 of recurrent finger cold exposure we have used plethysmography, 

 thermometry, and calorimetry concurrently, and we do not see 

 any of these GIVD differences you report. 



ADAMS: I think such calorimeter data are quite acceptable 

 for showing an increase in digital blood flow. It is possible, how- 

 ever, that one could have a change in circulation or circulatory 

 mechanisms, perhaps in an increased blood flow deep in the finger, 

 that would not be reflected in surface temperatures. 



EAGAN; How can you fool a plethysmography Calorimetry 

 will measure the average response over 30 minutes, if that is the 

 length of immersion. With thermometry you get something inter- 

 mediate in capability for detecting vascular change. It is slightly 

 more sensitive than calorimetry, but nevertheless, in vasocon- 

 stricted tissue, because of the thermal capacity of the tissue and 



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