GENERAL DISCUSSION 



Wallace: I should like to present a problem that arises when one 

 attempts to interpret chemical analysis of tissues from deficient 

 animals in terms of histological appearance. Skeletal muscle taken 

 from potassium-deficient animals is low in potassium, high in sodium, 

 high in its content of basic amino acids and probably low in bicar- 

 bonate content. When the muscle is examined histologically one 

 sees apparently normal cells lying side by side with grossly abnormal 

 cells. Which cells account for the chemical abnormalities? I have 

 wondered if a cell can tolerate any deficit at all. Possibly, for the cell, 

 it is an all-or-none phenomenon. Does a tissue as a whole become 

 deficient in a sort of quantum fashion, cell by cell rather than by an 

 over-all shared process by all of the cells? Is it not necessary to get 

 down to a truly cellular level to further our understanding? 



Fourman: May I add to Prof. Wallace's problem? The kidney and 

 the heart show the morphological changes of potassium deficiency 

 before the other tissues. These two tissues, when they are analysed in 

 animals that have been made deficient in potassium, do not as a rule 

 show chemical evidence of potassium deficiency. I suppose they do if 

 you carry the deficiency far enough but as a rule they do not. It has 

 always been a puzzle to me why two tissues that have a normal 

 potassium content are the first tissues to show a potassium abnor- 

 mality. These two tissues are also ones that never rest, in the way 

 muscles do, and one wonders whether the fact that their function 

 requires the maintenance of a normal potassium content, with the 

 demand on the metabolic energy of the cell that this entails, carries 

 the seeds of their own destruction. 



Wallace: The analyses of Orent-Keiles and McCoUum do show 

 deficits of potassium in cardiac muscle taken from deficient rats (1941. 

 J. hiol. Chem., 140, 337). However, most workers have not shown 

 the same thing. 



Black: Jean Oliver and co-workers (1957. J. exp. Med., 106, 563) 

 have done work on the localization of the morphological defect in 

 the nephron of potassium-depleted animals, and this seems to be 

 limited to the proximal and the collecting tubules. Dr. Fourman's 

 difficulty may not be so real if the lesion is as sharply localized as 

 that. With analysis of the whole kidney that may just be a failure 

 to detect a limited local deficiency of potassium. 



Milne: Part of the difficulty may be this: is not the necrosis or 

 degeneration in the cell possibly due to the fall in intracellular pH, 

 not primarily to potassium deficiency? I agree that kidney analyses 



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