RESPIRATORY REGULATION OF THE CO, CAPACITY 
OF THE BLOOD. 
I. HIGH LEVELS OF CO, AND ALKALI. 
By YANDELL HENDERSON anp H..W. HAGGARD. 
(From the Physiological Laboratory, Yale Medical School, New Haven.) 
(Received for publication, December 31, 1917.) 
The balance between acids and alkalies has come to be recog- 
nized as one of the most important of the equilibria of the living 
body. It is so important in fact that it appears never to be 
considerably altered except when the organism is practically 
moribund. ay 
The two modes of estimating the degree of equilibrium which, 
at the present time, appear to be most interesting are by meas- 
urement of the CO, content of the alveolar air and of the CO, 
capacity or ‘‘alkaline reserve” of the blood (Van Slyke). The 
view now prevailing is that in ‘‘acidosis” the accumulation of 
non-volatile acids in the body neutralizes the alkalies and causes 
a reduction-in both measurements. | 
In the facts and conclusions which follow we do not question 
the essential correctness of this general conception in conditions 
of true acidosis. We do however attempt to show that many 
conditions simulating acidosis are really due to disturbance of 
another factor which exerts a powerful! influence upon the CO, 
capacity of the blood, and which may lead to an equilibrium at a 
new level. This factor is respiration. Abnormal breathing may 
even produce a disturbance such that equilibrium cannot be 
spontaneously restored. It may thus produce death. 
Recent papers by Scott,! Peters,? and others have recognized 
certain aspects of this factor. General recognition of its power 
will profoundly modify the present crassly mechanistic theoreti- 
1 Scott, R. W., Am. J. Physiol., 1917, xliv, 196. 
Peters, i) b.,.0r., Am.Ju PRhysiol., 1917, xl, l13; xliv, 84. 
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