CORRELATIVES OF WATER CONTENT 



231 



6 hours of copious, uniform water administration, the following 

 values result (table 25). At the end of 6 hours the urea concen- 

 tration in the blood was actually 3 niM, corresponding to a urea 

 content of the whole body of 14 millimols. This agrees with the 

 amount expected (last column) upon the assumptions mentioned. 

 The agreement makes it probable that the rate of urea formation 

 itself is actually unaffected by water excess. Another notable out- 

 come of the computation is that the urea content of the body ap- 

 proaches (at only half the control content, or Au-50) a new 

 balance, in which elimination of urea equals production of urea. 

 Chloride in plasma behaved similarly in the same test. 



6i 



Hours 



Fig. 130. Rate or concentration (in arbitrary units) in relation to time after water 

 ingestion. One test on dog E of Shannon ('36b, p. 208). Water was administered 

 by stomach at zero time (5.0% of Bo) and at 5.15 hours (1.5% of Bo). Urea Clearance = 

 urinary clearance of urea from plasma, in units of 2.0% of BoAour. Ureap Con- 

 centration = concentration of urea in plasma, in units of 0.8 millimols/liter. Urea Rate 

 = rate of urinary urea output, in units of 0.10 millimols/hour. Water Rate = rate of 

 urinary water output, in units of 0.4% of Bo/liour. 



To conclude that the kidneys are responsible for the depletions 

 of solutes in + AW is like blaming the pumping station for the 

 great flow of water from faucets near dinner time. In water 

 deficits the lesser renal clearances by themselves favor retentions 

 of solutes. 



The above relations for urea are shown in figure 130 as they 

 change with time during single loadings and unloadings of water. 

 Renal urea clearance there temporarily augments by 50 per cent. 

 Since water excesses are measured ordinarily as sensible loads, the 



