Studies in the Physiology of Muscular Exercise

In normal resting individuals, Parsons (1) found by calculation from electrometric determinations that the reaction of arterial and venous blood from the arm differed only by pH 0.02, the venous being less alkaline.Peters, Barr, and Rule (2) in three normal men calculated differences of only pH 0.01 to 0.00.No comparisons of the COz-combining capacity of whole blood from artery and vein have been found in the literature.Stadie and Van Slyke (3) compared the COz capa'city of arterial and venous plasma and showed that the venous was usually about 15 per cent higher.Joffe and Poulton (4) have demonstrated, however, that values for plasma COz capacity depend upon the tension under which blood previously existed in the body.Since the CO2 tension of venous blood is always higher than that of arterial, one should expect the capacity of venous plasma to be higher.Capacity determinations upon whole blood do not depend upon preexisting tensions and the results of Stadie and Van Slyke are, therefore, not applicable to whole blood studies.It has been!generally assumed that the CO2 capacity of arterial and venous blood is normally identical.In the experiments of the preceding paper, it was demonstrated that the reaction and COz capacity of both arterial and venous.blood were diminished after exercise.The degree to which each was changed in any particular experiment, however, was not