An electrolytic method for determining oxygen dissociation curves using small blood samples: the effect of...

1. A detailed account is given of an electrolytic method for determining the oxygen dissociation curve of fish blood using a single sample of 50-100 mul for the whole curve. The accuracy and some of the problems arising from its uses are discussed. 2. Oxygen dissociation curves have been determined for trout blood and human blood at temperatures of 15 and 37 degrees C. The relationship between P50 and temperature is similar to that obtained using other methods. Absolute values of P50 are generally lower than those obtained by other methods, especially in the case of fish blood. 3. The effect of PCO2 and pH on the oxygen dissociation curve of trout blood is tested and it is shown that PCO2 has a more marked effect than pH when the other factor is maintained at a constant level. The Bohr factor (delta log P50/delta pH) appears to be approximately the same and independent of the PCO2. 4. The P50 of ray blood determined from fish during and after an operation showed an increased Bohr factor.