Journal of Applied Physiology, Vol 64, Issue 6 2400-2409, Copyright © 1988 by American Physiological Society
Human whole-blood O2 affinity: effect of CO2
G. Kwant, B. Oeseburg, A. Zwart and W. G. Zijlstra
Department of Physiology, University of Groningen, The Netherlands.
The proton Bohr factor (phi H = alpha log PO2/alpha pH), the carbamate Bohr
factor (phi C = alpha log PO2/alpha log PCO2), the total Bohr factor (phi
HC = d log PO2/dpH[base excess) and the CO2 buffer factor (d log PCO2/dpH)
were determined in the blood of 12 healthy donors over the whole O2
saturation (SO2) range. All three Bohr factors proved to be dependent on
SO2, although to a lesser extent than reported in some of the recent
literature. At SO2 = 50% and 37 degrees C, we found phi H = -0.428 +/-
0.010 (SE), phi C = 0.054 +/- 0.006, and phi HC = -0.488 +/- 0.007. The
values obtained for phi H, phi C, and d log PCO2/dpH were used to calculate
phi HC. Calculated and measured values of phi HC proved to be in good
agreement. In an additional series of 12 specimens of human blood we
determined the influence of PCO2 on phi H and the influence of pH on phi C.
At SO2 = 50%, phi H varied from -0.49 +/- 0.009 at PCO2 = 15 Torr to -0.31
+/- 0.010 at PCO2 = 105 Torr and phi C from 0.157 +/- 0.015 at pH = 7.80 to
0.006 +/- 0.009 at pH = 7.00. When on the basis of these data a
second-order term is taken into account, a still slightly better agreement
between measured and calculated values of phi HC can be attained.
