OXYGEN CONSUMPTION OF MAMMALIAN TISSUES AT 

 REDUCED TEMPERATURES 



F. A. FUHRMAN 



The problem of temperature coefficients of isolated tissues, which Dr. ilrown and 

 Dr. Horvath touched on, can be summarized in figure 1. 



The curve which Dr. Adolph showed was the one relating the oxygen consump- 

 tion of the brain to temperature over a range of approximately zero to 40° C. I have 

 added to that curve the oxygen consumption of a number of other tissues deter- 

 mined in the same way. These are all slices of tissue studied under as nearly identi- 

 cal conditions as possible in Ringer's phosphate-glucose solution. 



In general all of these curves are similar to the one which Dr. Adolph showed 

 for the brain in that they are smooth over most of their course. It is now possible 

 to carry this below zero for the brain and, if freezing does not occur, the curve is 

 still smooth, a continuation of the one shown here. 



Temperature coefficients at the various temperatures are not necessarily constant 

 over the whole temperature range, and they are not constant from one tissue to 

 another. The temperature coefficient, Qio, of the brain is approximately constant 

 over a good part of the temperature range (10° to 37.5° C). For the other tissues 

 this may or may not be so. In general the Qio'5 range between 2 and 3 over the 

 central part of the temperature range, from approximately 10° or 15° C. up to about 

 35° or 37° C. Outside of this range the temperature coefficients may fluctuate 

 widely, in general becoming much larger. 



It has been shown by Field and his co-workers that at 37° C. one may ol)tain a 

 reasonable approximation of metabolic rate of the whole animal by summating the 

 metabolic rate of the individual tissues, in which case if one makes allowances for 

 the contribution of respiratory activity, muscle tension and cardiac activity, one 

 approximates the total metabolic rate of the animal from summating the rates of the 

 tissues. 



We have made some preliminary calculations of this kind at 18° C, using for the 

 rat at that temperature the total oxygen consumption obtained by Dr. Adolph, which 

 has been confirmed in a few experiments of our own. At this temperature also the 

 metabolic rate of the hypothermic animal can be largely accounted for as the sum- 

 mated respiration of the individual tissues. Again, this illustrates that there appears 

 to be no interference with oxygen delivery over this range of from approximately 

 zero to 37° C. 



REFERENCES 



1. Fulirman, F. A., and Fifld, J.: Influence of temperature on tlie stimulation of oxygen 



consumption of isolated brain and kidney bv 2-4 dinitr()i>]ien()l, J. Pliarmacol. Kxper. 

 Therap. 75: 58-63, 1942. 



2. Fuhrman, F. A., and Field, J. : Factors determining tbe metabolic rate of excised liver 



tissue. I. Efifect of slice thickness and tissue injury on oxygen consumption. II. Effect of 

 glycogen content on oxygen consumption. III. l\ffecl of temperature on oxygen con- 

 sumption, Arch. Biochem. 6: 337-349, 1945. 



3. Fuhrman, G. J., Fuhrman, F. A., and Field, J. : Metabolism of rat heart slices, with special 



reference to effects of tem])erature and anoxia, .'\m. J. Physiol. 16S: CAZ-CA?, 1950. 



50 



