Discussion 221 



the major organic acid constituent of the urine which is passed im- 

 mediately after birth. In addition, urine passed during the first 24 

 hours of hfe contains mahc acid, glycohc, lactic, ^-hydroxybutyric, 

 succinic, and a-ketoglutaric acids, but not aconitic acid. With this 

 method one can detect a minimum of 20 y.g. of each of these organic 

 acids. 



Adolph : Is there any appreciable accumulation of organic acids in the 

 newborn during the first week of life? At this stage the individual is very 

 insensitive to the hydrogen-ion concentration changes as far as the 

 breathing is concerned, and I was wondering whether it is also insensitive 

 as far as excretion is concerned. 



Zweymiiller : We are now working on the detection and identification 

 of the organic acids found in the urine of normal newborn babies, and the 

 next problem will be to identify those found in the urine of hypoxaemic 

 newborn babies. 



Karvonen : Did you find any pyruvate or does it come out with this 

 method? 



Zweymiiller : We have not found a pyruvic acid spot, but we have not 

 added pyruvic acid to the urine so we do not know exactly where the 

 spot should appear on the paper. 



Karvonen : I understand that increased excretion of pyruvate has been 

 found during the first few days of life (Tallqvist, H. (1952). Thesis, 

 Hameenlinna). 



Zweymiiller : There is an interesting paper about some work on the 

 output of organic acids in potassium depletion in which pyruvic acid, 

 lactic acid, a-ketoglutaric acid, and citric acid were estimated, but this 

 was done on normal adults (Evans et al. (1957). Clin. Sci., 16, 53). 



Fourman : The hydrogen ion in the allantoic sac must come from some- 

 where, it cannot be manufactured. It must come in the end from the 

 mother and since she cannot manufacture the hydrogen ion it must 

 ultimately come from her diet. So what happens if you feed alkali to 

 the mother pig? 



Widdowson : We have not tried that. 



Milne: It is well shown in your paper. Dr. Widdowson, how the new- 

 born baby copes with its normal environment. I would agree that the 

 organic acid level, especially that of citrate, is proportionally much 

 higher than in the adult. Ob\4ously in assessing the efficiency of the 

 kidney, particularly in excreting an acid load, one must give it a maxi- 

 mum challenge and, though I see the difficulties of this in human experi- 

 mentation, it would be extremely interesting to do this in the newborn 

 animal. There seem to be two separate aspects of excretion of acid by the 

 kidney. One is the ability of the kidney to excrete a maximum amount of 

 hydrogen ion per day and clearly that can only be assessed by giving a 

 prolonged acid load. The other is the ability of the kidney to maintain 

 a hydrogen ion gradient between urine and plasma, in other words the 

 production of a minimum urinary pH. I would be very interested in 

 having data on whether the minimum pH of adult urine is similar to the 

 minimum pH of newborn urine, whether the ammonia excretion can 

 increase on prolonged acid ingestion proportionally to that of the adult, 



