Post-natal changes in oxygen affinity and the concentration of 2,3-diphosphoglycerate in cat blood

Abstract

The respiratory properties and concentrations of 2,3-diphosphoglycerate (2,3-DPG) in kitten blood were studied during fetal life and from birth to 100 days of age and compared with adult values. Fetal blood had a hemoglobin concentration (Hb) of 10.4 g%, within the normal adult range. Newborn kittens in the first 24 hr of life had Hb values averaging 13.4 g%. Hb then fell gradually, reaching a low value at about 35 days of age and subsequently rising. At 100 days of age Hb values were again similar to those of adult cats. The pH difference across the red cell membrane was significantly higher during fetal life than after birth. The P 50 value for fetal blood was similar to adult blood (34.1 ± 0.6 vs. 35.2±0.8 mm Hg, respectively) but P 50 values within the first 24 hr of life were significantly lower (P<0.01) than adult values. At 35 days of age, the mean P 50 (37.8±1.1 mm Hg) was significantly higher (P<0.01) than for adult cats. At 100 days, P 50 values were similar to adult cat blood. Concentrations of 2,3-DPG in blood from fetuses and kittens of all ages were low compared to humans and not significantly different from values of adult cat blood. The sensitivity of kitten and cat Hb to 2,3-DPG was similar and very low compared with human hemoglobin A. Starch gel electrophoresis at pH 8.6 showed no difference in kitten and adult cat Hb. Both have two major components. The fall in P 50 after birth is attributed to a fall in trans-membrane pH difference, but the subsequent increase in P 50 is unexplained by our data.