50 Paul Fourman and Patricia M. Leeson 



patients. The potassium content was normal. The sodium 

 content, far from being lower than normal, was in fact at the 

 upper limits of the normal. The chloride content was simil- 

 arly high. For this to happen with a low concentration of 

 sodium in ECF, the amount of ECF in the muscle samples 

 must have been larger than normal. 



Hypertonic saline 



The infusion of hypertonic saline produced only a transient 

 increase in the plasma [Na]. 



The response was studied in detail in Albert. He had 500 ml. 

 of 5 per cent sodium chloride (436 m-equiv.) infused over 

 about three hours on 15th June when his plasma [Na] was 

 initially 127 m-equiv./l. (Fig. 1). 



The immediate response to this infusion was an osmotic 

 diuresis with an output of 7-3 ml./min. of urine containing 

 330 m-osm. and 155 m-equiv. of sodium per litre. During 

 the infusion he excreted 80 m-equiv. of sodium. The plasma 

 [Na] increased to 143 m-equiv./l. during the infusion and was 

 138 m-equiv./l. at the end. In the following 21 hours he 

 responded quite differently. He excreted only 55 m-equiv. of 

 sodium and his urine flow fell to 0-2 ml./min. with a concen- 

 tration of 696 m-osm. /I. He was thus retaining water and 

 diluting the sodium he had retained. Three days later his 

 plasma [Na] was again only 130 m-equiv./l. 



Ivor had infusions of 300 ml. of 5 per cent sodium chloride 

 on 22nd June and 540 ml. on 24th June. We did not make 

 very detailed studies of his response, but the plasma [Na] 

 before and after the second infusion was 113 and 115 m- 

 equiv./l. During the first three hours of this infusion when 

 he had received 190 m-equiv. he excreted only 30 m-equiv. 

 Both the infusions were followed by a retention of water. 



These are not the responses one would expect from salt- 

 depleted patients (Black, Piatt and Stanbury, 1950). They 

 imply that the osmolality of the body water was being 

 maintained even at the expense of increasing the volume of 

 the extracellular fluid. This is the normal response to hyper- 



