Acid Base Equilibrium of the Blood. 



179 



brings about. Under the circumstances, it is necessary to conclude 

 that the effect on the refractory period is the more important. 

 It is also a matter of interest that the dogs are not affected uni- 

 formly by the drug. It is to be recalled that a similar lack of 

 uniformity in action exists in patients. We have, as yet, no 

 explanation of this phenomenon. Muscular irritability is a third 

 factor which must be considered in this connection, but a discussion 

 of this, as well as of the details of the experiments now described 

 and of those formerly reported, we reserve for the full account of 

 our studies. 



81 (1828) 



The acid base equilibrium of the blood following vigorous mus- 

 cular exercise. 



By DAVID P. BARR. 



[From the Russell Sage Institute of Pathology and the Second 

 Medical Division of Bellevue Hospital, New York City.] 



Immediately following short periods of vigorous muscular 

 work, there is a marked reduction in the bicarbonate content of 

 the blood, a phenomenon observed by Christianson, Douglass and 

 Haldane in 1914. 1 The initial purpose of the present investigation 

 has been to discover what changes in the reaction and the C0 2 

 tension of arterial blood accompany the diminution in bicarbonate. 

 For this purpose, four individuals without demonstrable organic 

 defects but of varying grades of apparent fitness were selected 

 for experiment. Each did on a Krogh bicycle ergometer a stand- 

 ard amount of exercise which consisted of the performance of 

 approximately 3,500 kilogrammeters of work in three and a half 

 minutes. The method employed upon the blood is that introduced 

 by Henderson and Haggard 2 and consists in the simultaneous 

 determination of the carbon dioxide absorption curve of blood at 

 body temperature and the carbon dioxide content of the arterial 

 blood as it occurs in the body. The reaction of the arterial blood 

 is calculated from the H 2 C0 3 /BHC0 3 ratio after the formula of 

 Hasselbalch. Arterial blood was drawn from the brachial or 



1 Christianson, J., Douglass, C. G., and Haldane, J. S., Jour. Physiol., 1014, 

 xlviii, 244. 



J Henderson, Y., and Haggard, H. W., J. Biol. Chem., 1919, xxxix, 163. 



