Fixed acid and carbon dioxide Bohr effects as functions of hemoglobin-oxygen saturation and erythrocyte pH in the blood of the frog, Rana temporaria.

Using a thin film, dynamic recording technique, the pH sensitivity of the oxygen equilibrium (Bohr effect) of whole blood in the frog Rana temporaria, and its dependence on CO2 and fixed acids and on plasma and erythrocyte pH values were measured. Under standard conditions (20 degrees C, PCO2 = 14.7 mm Hg, pH = 7.65) the oxygen equilibrium could be described by a P50 value of 38 mm Hg and n50 of 1.8 Hill plots of the oxygen equilibria showed increased cooperativity in oxygen binding with increasing saturation (n20 congruent to 1.2, n80 congruent to 4.0). Values of fixed acid and CO2 Bohr factors (phi AH and phi CO2, respectively) were similar at specific saturations (S20, 50, 80) but showed saturation dependence with high values occurring at high saturation. The same statements also hold for the intracellular Bohr factors (derived from the relation between blood P50 and erythrocyte pH) although the values of both phi AH and phi CO2 now were greater than those related to blood pH.