6 The Chemistry of the Injured Cell 



view that the intracellular compartment is hypertonic relative to 

 the extracellular fluid. 



The mechanism whereby water is excluded from the normal cell 

 appeared to be revealed by a number of investigations all showing 

 that the exclusion of water appeared to depend on energy produc- 

 ing reactions in the cell. Thus many of the various types of injury 

 leading to swelling of tissues in vitro interfere with cell metabolism. 

 Anaerobiosis, low temperature, poisoning with 2:4 dinitrophenol, 

 cyanide, azide or heavy metals, all block the oxidative formation of 

 high energy phosphate bonds and all cause water influx into cells in 

 vitro. In red blood corpuscles, too, the general principle holds. 



Robinson (1950) showed that on incubation in hypotonic sur- 

 roundings, metabolising tissue slices became water-logged less 

 rapidly than did similar slices whose metabolism had been in- 

 hibited by cooling to 0°c. His experiments seemed to support the 

 argument that water was prevented from entering a normally hyper- 

 tonic intracellular compartment by energy-yielding metabolic pro- 

 cesses. 



Two sets of observations have served to invalidate this view. 

 The first observations concern direct measurement of the intracellu- 

 lar tonicity. This was first attempted by determination of the freez- 

 ing point of tissues as compared with that of blood. All such experi- 

 ments have shown tissues to yield values about 150 per cent of those 

 of blood. A similar result was obtained by measurement of melting 

 point depression. The effect of these findings was apparently to con- 

 firm the view that the cell was hypertonic relative to its surround- 



ings. 



However, this interpretation was challenged because it was 

 shown that after removal from the body, even at 0°, there occurred 

 in the tissues a very rapid rise in the value for freezing point de- 

 pression due presumably to autolysis (Conway and McCormack, 

 1953) . In fact, a calculation was made showing that if corrected for 

 post mortem changes, the freezing point depression of tissues was 

 similar to that of blood. These conclusions did not pass unchal- 

 lenged but freezing point determinations on tissues previously 

 heated to prevent autolysis indicated that the cells were in fact 

 isotonic with blood (Appleboom, 1957) . The truth of this state- 

 ment is indicated by recent experiments quoted by Leaf (1959) . In 



