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Objective: The prenatal hypoxia induces a complex response, and numerous functional systems are involved to prevent the damage of embryo. The mechanism of the developmental response to hypoxia is not entirely clear. We studied the changes of oxygen tension in amniotic fluid (AF) during development of chick embryo and under the influence of acute and chronic hypoxia.
Methods: Chick eggs were incubated at 37.5°C. Po2, Pco2, and pH were measured in samples of AF using blood gas analyzer Radiometer Copenhagen ABL 605 on incubation days 10 (D10), 12 and 14 in control and after the egg exposure to acute hypoxia (10%O2 for 10min) or chronic hypoxia (15%O2 since D6).
Results: In control, the Po2 in AF was about 55 mmHg and remained relatively constant during this period. The Pco2 significantly increased from 19.85 ± 0.52 to 30.22 ± 1.87 mmHg, while pH significantly decreased from 6.91 ± 0.03 to 6.58 ± 0.05 since D10 to D14.
Acute hypoxia reduced the Po2 in AF by 25; 23 and 16% from the control values on D10, 12 and 14, respectively. The Pco2 increased, but the effect was significant only on D12. The pH decreased and this effect was more pronounced on D14.
Chronic hypoxia increased the Po2 in AF by 20% from the control value on D10, and did not change it significantly on D12 and D14. The Pco2 decreased on D10, D12, but didn?t change on D14. The pH decreased on D10 and D12, but rose significantly on D14.
Conclusion: The effects of acute and chronic hypoxia on gases values in AF were different. These results are discussed in regards to the role of oxygen in AF for the embryo metabolism during hypoxia and for the function of amniotic membrane, which is not vascularised and may use oxygen from amniotic fluid. This work was supported by RFBR grant 05-04-49434.