Oxygen carriage and carbonic anhydrase activity in the blood of a marsupial, the Tammar Wallaby ( Macropus eugenii), during early development

Blood O 2 transport and Hb type have been studied in pouch young and adult of a marsupial, the Tammar Wallaby. The O 2Hb equilibrium curves (at 35.5 °C and P CO 2 = 34 Torr) had a high P 50 in the first few days of life, up to 49 Torr. This fell to 32 Torr by 2 weeks of age. Also ( Δ log P 50/ δ P...

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Veröffentlicht in:Respiration physiology 1988-07, Vol.73 (1), p.69-86
Hauptverfasser: Holland, R.A.B., Rimes, A.F., Comis, A., Tyndale-Biscoe, C.H.
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Sprache:eng
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Zusammenfassung:Blood O 2 transport and Hb type have been studied in pouch young and adult of a marsupial, the Tammar Wallaby. The O 2Hb equilibrium curves (at 35.5 °C and P CO 2 = 34 Torr) had a high P 50 in the first few days of life, up to 49 Torr. This fell to 32 Torr by 2 weeks of age. Also ( Δ log P 50/ δ P CO 2 ) was low but it rose to adult levels by 2 weeks of age. The curves in these early pouch young showed a change in Hill coefficient (n H) at between 32 and 62% saturation, n H rising to more than 4.0 at higher O 2 saturations. This indicates interaction between more than 4 Hb subunits. Model of calculations showed that such curves could be produced by a mixture of 2 Hb components; one with a low P 50 and low n H, and one with a high P 50 and high n H. In this model the n H values were different from the n H values of either component. The temperature effect of P 50 in early pouch young was higher than in adult Tammars and similar to that reported for adult eutherians. In the first 4 days all red cells were nucleated and four Hb types were present. Carbonic anydrase activity in the blood before birth was about 30% of the adult levels. These levels remained until 2 days after birth, when a rapid rise in activity began, near-adult levels being reached at 5 days depsite the animals being still very immature.
ISSN:0034-5687
DOI:10.1016/0034-5687(88)90128-4