Respiratory changes in human red cells.

To investigate physiological respiratory changes in human red cells, we measured automated red cell parameters in samples from the pulmonary and radial arteries of 86 patients undergoing aorto-coronary bypass and from the pulmonary artery and the aorta in 23 patients. Our results showed higher mean corpuscular volume (88.53 +/- 5.06 fl vs. 88.12 +/- 4.94 fl, P < 0.000001), haematocrit (0.369 +/- 0.039 vs. 0.367 +/- 0.038, P < 0.0005), red cell distribution width (43.38 +/- 4.16 vs. 43.04 +/- 4.05 fl, P < 0.000001) and a lower mean corpuscular haemoglobin concentration (338.3 +/- 15.9 vs. 339.9 +/- 16.8 g/l, P < 0.005) in pulmonary arterial as compared to radial arterial blood. There were no differences with respect to haemoglobin concentration, red blood cell count, or mean corpuscular haemoglobin. Similar differences were observed between pulmonary arterial and aortic blood. Our results suggest cyclic respiratory modifications of red cell parameters attributable to the CO2 Jacobs-Stewart cycle.