title: Oxygen carriage and carbonic anhydrase activity in the blood of a marsupial, the Tammar wallaby (Macropus eugenii), during early development.
abstract: Blood O2 transport and Hb type have been studied in pouch young and adult of a marsupial, the Tammar Wallaby. The O2-Hb equilibrium curves (at 35.5 degrees C and PCO2 = 34 Torr) had a high P50 in the first few days of life, up to 49 Torr. This fell to 32 Torr by 2 weeks of age. Also (delta log P50/delta PCO2) 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 (nH) at between 32 and 62% saturation, nH rising to more than 4.0 at higher O2 saturations. This indicates interaction between more than 4 Hb subunits. Model calculations showed that such curves could be produced by a mixture of 2 Hb components; one with a low P50 and low nH, and one with a high P50 and high nH. In this model the nH values were different from the nH values of either component. The temperature effect on P50 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 anhydrase 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 despite the animals being still very immature.
mesh_terms: D000375:Aging; D000818:Animals; D002256:Carbonic Anhydrases / Q000097:blood*; D004912:Erythrocytes / Q000201:enzymology; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D007614:Macropodidae / Q000097:blood* / Q000196:embryology / Q000254:growth & development; D008394:Marsupialia / Q000097:blood*; D010100:Oxygen / Q000097:blood* / Q000502:physiology; D010108:Oxyhemoglobins / Q000378:metabolism; D013696:Temperature
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; D002256:Carbonic Anhydrases; D010100:Oxygen