Standard and pH-affected hemoglobin-O2 binding curves of Sprague-Dawley rats under normal and shifted P50 conditions.

1. The oxygen saturation (SO2) was determined of Sprague-Dawley rat blood having increased hemoglobin (Hb)-O2 affinity (P50 < 37 mmHg) or capacity (Cmax) over a range of pH's. 2. Rats were untreated (K), or had passed 14 d drinking 0.5% saline (C; ctrl) or NaOCN (N; chronically low P50, high Cmax), 5000 m altitude acclimatization (H; high Cmax), or exchange transfusion with OCN(-)-Hb red cell blood (X; acutely low P50). 3. The P50 [mmHg], Hill's "n", and Cmax [ml O2/100 ml], measured after tonometry, were 36.0, 2.60 and 20.6 (K), 32.6, 2.50 and 21.8 (C), 18.3, 2.35 and 23.9 (N), 36.0, 2.60 and 29.4 (H), and 24.9, 2.73 and 22.3 (X). 4. Oxygen dissociation curves (ODC's), derived from simultaneous SO2 and PO2 measurements during deoxygenation (PO2: 100-0 mmHg) of blood (normal and acidified with CO2 or lactic acid), delivered Bohr coefficients (BCCO2, BCLac) each differing between groups (C vs N) above SO2 50%; within groups BCCO2 vs BCLac differed at SO2 10-90% (P < 0.05). 5. Group-specific ODC's and pH-shifted curves (+/- 0.05, +/- 0.10 and +/- 0.15 units from 7.4, relying on BCCO2) are plotted for direct reading of SO2 and, with Cmax, accurate data on blood O2 content are obtained; corrections for lactic acidosis are discussed.

[1]  J. Severinghaus,et al.  pH and molecular CO2 components of the Bohr effect in human blood. , 1966, Scandinavian journal of clinical and laboratory investigation.

[2]  R. Schmidt,et al.  Physiologie des Menschen , 1993, Springer-Lehrbuch.

[3]  M. Hlastala,et al.  Saturation dependency of the Bohr effect: interactions among H-+, CO2, and DPG. , 1975, Journal of applied physiology.

[4]  Christian Bohr,et al.  Ueber einen in biologischer Beziehung wichtigen Einfluss, den die Kohlensäurespannung des Blutes auf dessen Sauerstoffbindung übt1 , 1904 .

[5]  L. H. Gray,et al.  Determination of the oxyhaemoglobin dissociation curves for mouse and rat blood , 1964, The Journal of physiology.

[6]  C. Bauer,et al.  Influence of chronic and acute hypoxia on oxygen affinity and red cell 2,3 diphosphoglycerate of rats and guinea pigs. , 1971, Respiration physiology.

[7]  J. Graziano,et al.  Pharmacology of cyanate. I. General effects on experimental animals. , 1973, The Journal of pharmacology and experimental therapeutics.

[8]  B. Teisseire,et al.  Effects of chronic changes in hemoglobin-O2 affinity in rats. , 1979, Journal of applied physiology: respiratory, environmental and exercise physiology.

[9]  J. Eaton,et al.  Survival at Extreme Altitude: Protective Effect of Increased Hemoglobin-Oxygen Affinity , 1974, Science.

[10]  W. Schmidt,et al.  Blood gas transport properties in endurance-trained athletes living at different altitudes. , 1990, International journal of sports medicine.

[11]  F. Hall.  Minimal utilizable oxygen and the oxygen dissociation curve of blood of rodents. , 1966, Journal of applied physiology.

[12]  P. Vaupel,et al.  [PO-2-PCO-2-pH-nomograms for rat blood at 37 degrees C (author's transl)]. , 1975, Der Anaesthesist.

[13]  R. W. Bullard,et al.  Blood characteristics and volume in two rodents native to high altitude. , 1966, Journal of applied physiology.

[14]  K. Braumann,et al.  Red cell age effects on metabolism and oxygen affinity in humans. , 1987, Respiration physiology.

[15]  C. Bauer,et al.  Causes of high blood O2 affinity of animals living at high altitude. , 1977, Journal of applied physiology: respiratory, environmental and exercise physiology.

[16]  C. Cartheuser.  Progressive hypoxia until brain electrical silence: a useful model for studying protective interventions. , 1988, Canadian journal of physiology and pharmacology.

[17]  R. Winslow,et al.  Normal whole blood Bohr effect in Peruvian natives of high altitude. , 1985, Respiration physiology.

[18]  O. Siggaard‐Andersen.  The acid-base status of the blood. , 1963, Scandinavian journal of clinical and laboratory investigation.

[19]  T. Asakura.  Automated method for determination of oxygen equilibrium curves of red cell suspensions under controlled buffer conditions and its clinical applications , 1979, Critical care medicine.