Temperature and pH effects on the oxygen equilibrium curve of the thoroughbred horse.
A new oxygen equilibrium curve is defined for the Thoroughbred horse under standard conditions of 37 degrees C, pH = 7.4 and PCO2 = 5.33 kPa. The "standard" P50 for the Thoroughbred is, at 2.83 +/- 0.04 (SE of mean) kPa, significantly lower than that found for the Hanoverian horse (3.17 +/- 0.03 kPa) by Clerbaux et al. (Can. J. Vet. Res. 50: 188-192, 1986), and lower than other values for horses in the literature. Using data from Butler et al. (J. Exp. Biol. 179: 159-180, 1993), curves were also constructed, in vitro, under simulated conditions of intense exercise to examine the individual effects of pH, temperature and PCO2 on the standard curve. The fixed acid Bohr coefficient is similar to that in humans (-0.41) whereas the temperature coefficient is, at 0.019, lower than that for humans. The coefficients were shown to be saturation dependent.
Smale
K
K
Department of Comparative Physiology, Animal Health Trust, Newmarket, Suffolk, UK.
Butler
P J
PJ
D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006736:Horses / Q000097:blood*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D010100:Oxygen / Q000097:blood*; D005082:Physical Exertion; D012016:Reference Values; D013045:Species Specificity; D013696:Temperature
D006454:Hemoglobins; D002245:Carbon Dioxide; D010100:Oxygen