Intracellular pH of whole body and erythrocytes was measured in patients with moderate chronic stable hypercapnia caused by chronic obstructive lung disease. These values were not significantly different from those of normal subjects or from normal values reported in the literature. Unlike acute hypercapnia, mean whole body intracellular pH values were maintained in a normal range despite arterial pH values which varied between 7.27 and 7.46. The percentage of total body water was not significantly different between hypercapnics and normal subjects. However, extracellular water level was higher and intracellular water level was lower. Although plasma chloride concentration [CI-] was significantly lower in hypercapnics than in normal subjects, total body chlorides per kilogram body weight was not significantly different between the groups. Plasma, muscle, and red blood cell sodium and potassium levels did not differ significantly between the hypercapnics and the normal group.
The precise significance of the changes in acid-base