GLUCOSE AND OXYGEN UTILIZATION IN SYMPATHETIC GANGLIA 95 



move lactate. The volume of fluid was kept small, 20 to 30 microliters, so that 

 about 10% of the glucose was removed in one hour. Glucose was initially pres- 

 ent in a concentration of 1 gm. per liter. At the end of about an hour the vessel 

 was exchanged for one containing fresh solution. The accumulated samples 

 were analyzed for glucose by the method of Park and Johnson (1949) and for 

 lactate by the method of Barker and Summerson (1941). In these analyses the 

 usual steps involving precipitation of proteins were omitted because there was 

 no reason to expect much protein to appear in fluid bathing a ganglion with the 

 connective tissue sheath still intact. The results on resting uptake of glucose 

 did not differ significantly from those found earlier using a method based on 

 glucose oxidase, which was more specific for glucose than that used here (Ed- 

 wards and Larrabee, 1955). 



Weights 



At the end of each experiment the tissue was dried at 90° to 100°C. for at. 

 least }4 hour, which was sufficient to reach constant weight. All results are 

 expressed in terms of dry weight of tissue, which was usually between 200 and 

 400 micrograms. The only exception is in Fig. 10, where rates are based on wet 

 weights. 



Results 

 Resting Metabolism 



The average rate of resting oxygen uptake by 18 excised rat ganglia was 

 298 ± 8 micromoles per dry gm. hr. (mean ± s.e.m.). This is not particularly 

 interesting in itself. More information was gained by comparing this result with 

 rates of glucose uptake and lactate production. 



During the first hour or two after excision a typical ganglion produced a 

 significant amount of lactate, about }/% as many micrograms as glucose was con- 

 sumed. Rates for both glucose and lactate rose slowly for several hours, but 

 they kept in step, so that the differences between them stayed constant. The 

 lactate presumably came from the glucose, since its production stopped when 

 glucose was withdrawn. For further analysis we must consider possible des- 

 tinies of glucose other than (a) lactate. Presumably some glucose was (b) 

 oxidized to C0 2 and water. Some may have been (c) polymerized to glycogen 

 and some may have gone to (d) other miscellaneous fates, including loss as 

 pyruvate, acetate, or other intermediates. Lacking definite information we will 

 assume for the present that amounts going to glycogen and the "other" des- 

 tinies were negligible. Our chief justification for this assumption is that, when 

 oxidation was stopped by removal of oxygen, then all the glucose taken up 

 (22.9 mg./dry gm. hr.) was recovered as lactate (22.2 mg./dry gm. hr.), within 

 the limits of accuracy of our methods. Thus the amount of glucose going to fates 

 (c) and (d) must have been trivial, at least under conditions of anoxia. 



