242 



N. W. Shock 



trend was not statistically significant. The other major 

 electrolytes, sodium and chloride, do not show any age trend 

 (de Billis, 1954; Herbeuval, Cuny and Manciaux, 1954; Lippi 

 and Malerba, 1955). In our own laboratory we have found no 



55 65 



MEAN AGE 



Fig. 12. Trends in the acid-base equilibrium of the 

 blood of males with increasing age. Average curves 

 from top to bottom include percentage of red cells, 

 serum pH at 38°, carbon dioxide tension expressed 

 in millimetres of mercury, serum bicarbonate and 

 blood carbon dioxide content, both expressed in milli- 

 moles per litre. The vertical lines indicate ± one 

 standard error of the mean. Data for the 25-year de- 

 terminations taken from : Hamilton and Shock (1936). 



(From : Shock and Yiengst, 1950). 



systematic age changes in the total osmotic pressure of the 

 plasma or its water content. The bicarbonate content of the 

 plasma and the pH do not show significant age trends (Shock 

 and Yiengst, 1950). Thus, under basal conditions the kidney 

 is able to regulate the acid-base equilibrium of the body 

 adequately, even to advanced ages (Fig. 12). Lewis and 



