Scientific Proceedings (68). 



112 (1044) 



Changes in blood alkalinity during digestion. 



By Donald D. Van Slyke, Glenn E. Cullen and Edgar 



Stillman. 



[From the Hospital of the Rockefeller Institute.] 



It has been noticed by former observers that the alveolar 

 carbon dioxide tension usually rises after a meal. Two diam- 

 etrically opposite explanations have been possible: (1) Maldiges- 

 tion products displace carbon dioxide from the blood, and during 

 the displacement the rate at which carbon dioxide passes from 

 blood to lungs is increased. (2) The blood becomes more alkaline, 

 as the result of secretion of gastric hydrochloric acid, or absorp- 

 tion of alkaline digestion products. Consequently the carbon 

 dioxide capacity of the blood is increased, and in equilibrium with 

 it the carbon dioxide tension of the alveolar air rises. 



We have determined on each of a number of subjects, in condi- 

 tions of approximate digestive rest and of digestive activity, the 

 following data: (1) Alveolar carbon dioxide tension; (2) Alkaline 

 reserve of the plasma as indicated by its ability to maintain its 

 alkalinity after addition of acid; (3) Alkaline reserve of the plasma 

 as indicated by the amount of carbon dioxide with which it can 

 combine. The results show that the reserve alkalinity of the 

 plasma increases during digestion, the alveolar carbon dioxide 

 increasing simultaneously. The second of the above explanations 

 is therefore correct. The cause of the increase in alkaline reserve 

 is being further studied. 



