Pressure increases oxygen affinity of whole blood and erythrocyte suspensions

increases oxygen affinity of whole blood and erythrocyte suspen-sions. J. Appl. Physiol. 61(Z): 486-494, 1986.-Effect of hydro-static pressure (HP) on whole blood (WB) or erythrocyte suspension hemoglobin (Hb) O2 affinity has been studied using newly developed techniques. O2 partial pressure at which he-moglobin is half-saturated with O2 (P & measurements were made at 5 HP (1, 26, 51, 76, and 126 ATA) on thin films of human WB or erythrocytes at 37°C. CO, partial pressure of WB was either 28 or 57 Torr (film pH 7.51 or 7.31). HP increased affinity of erythrocytes and WB. For erythrocytes in tris(hydroxymethyl)aminomethane buffer, the ratio (r) of P,, (1 ATA)/P,, (51 ATA) was 1.089 (P < 0.01) at pH 7.0. WB P,, decreased with HP at a rate of-3.3 x lo- ’ Torr atm-l; change in P,, at higher HP vs. 1 ATA was highly significant (P < 0.01). No effect of HP was seen on the CO, Bohr coefficient