DIVEKSE COMPONENTS 



335 



creted or oxidized (fig. 166). The proportions represented by these 

 paths differ enormously at various glucose increments, represent- 

 ing quantitatively facts that are loosely known. At small incre- 

 ments practically all glucose is transformed, presumably to other 

 forms of carbohydrate. While the rates of synthesis and oxidation 

 are limited to about 3.6 gm./kg. hr., excretion is not limited but aug- 

 ments in proportion to the glucose load. One might envisage diffi- 

 cult situations for the organism if (a) there were no excretion of 

 glucose, (b) there were excretion of glucose at small loads (^=no 

 threshold), or (c) combustion of the extra sugar were not carried 



i: 



£" 6 

 I 



(D 



Z - 



+2 



+ 4 



+6 



+8 



+10 



Mean Glucose Load -qm/ kg. 



Fig. 166. Rate of net glucose disposal, and its partition, in relation to mean glu- 

 cose load in approximately steady states of glucose excess. Dog. Glucose was injected 

 intravenously at constant rates during 6 hours. The last 3 hours were taken in each 

 test, 29 or 48 tests being included in the 9 means. Glucose load was computed from 

 blood sugar concentrations and a Vd of 50% of Bo. Hence an increment of 1 gm.Ag- 

 or 0.1% of Bo = 2 gm./liter of whole blood; and since the initial content was 0.97 

 gm./liter of blood, 1 gm.Ag- or 5.55 millimols/kg. = 206 per cent of the control content 

 (Go). Data of Wierzuchowski ('36, pp. 314, 322, 327; '37b, p. 153). 



out. As it is, there are arrangements for meeting exceedingly large 

 influxes of glucose, and it has often been remarked that the organ- 

 ism has reserve means of meeting situations so extreme that they 

 may have never occurred in non-experimental situations. How 

 extreme these are, may be realized from the statement (Trimble 

 et al., '33) that glucose is ordinarily absorbed from the alimentary 

 tract at a rate of only 1 gm,/kg. hr. In Wierzuchowski 's experi- 

 ment, the dog speeds up its rates of disposal of glucose even to the 

 point where excretion of it is faster than removal of it by synthesis. 

 Total exchanges and turnovers are subject to small uncertain- 



