Water and Electrolytes in Congestive Failure 277 



According to Wesson, Anslow and Smith (1948) some 85 

 per cent of the filtered sodium and chloride is reabsorbed by 

 an active mechanism in the proximal tubule, irrespective of 

 the amount filtered. The reabsorption of the remaining 15 per 

 cent of sodium and chloride is limited by a fixed maximal 

 rate at which the distal tubular cells are able to reabsorb 

 these electrolytes. Whenever the tubular chloride load 

 decreases with a fall in glomerular filtration rate in the 

 presence of this maximal reabsorption capacity, almost all 

 of the filtered chloride is reabsorbed. Merrill (1949), Mokotoff, 

 Ross and Leiter (1948), Selkurt, Hall and Spencer (1949), 

 Stead (1951) and others are of the opinion that in congestive 

 failure this mechanism leads to the maximum reabsorption of 

 electrolytes and water; that is to say that the diminution of 

 glomerular filtration is such that with a normal unchanged 

 tubular reabsorption, water and electrolytes are retained. 



Our results are not in accord with the hypothesis of Wesson, 

 Anslow and Smith. In patients with severe congestive failure, 

 glomerular filtration rate did not rise towards normal levels 

 at the time of nocturnal diuresis ; in spite of this, the amount 

 of excreted chloride was far greater than the quantity of 

 chloride excreted at night in healthy subjects with a normal 

 glomerular filtration rate. Fig. 4 demonstrates that the 

 tubular reabsorption of chloride can vary markedly with a 

 constant tubular chloride load. It is clear, of course, that at a 

 given chloride load less chloride is reabsorbed at a high than 

 at a low urine flow. 



The concentration of chloride in urine exceeded its plasma 

 level in only seven out of 24 observations at high urine flow. 

 The increased urine flow, therefore, cannot be explained on 

 osmotic grounds by an increased excretion of chloride. 



The lower elimination of electrolytes and water in conges- 

 tive failure is, according to these findings, not caused only by 

 decreased glomerular filtration rate. Tubular reabsorption of 

 water and electrolytes increases as well. The same conclusion 

 is stated by Briggs and co-workers (1948), Kattus and co- 

 workers (1948), Davis and Shock (1949), Newman (1949),, 



