1. Respiratory and cardiovascular responses to oxygen and carbon dioxide levels in internally pipped chicken embryos Stephanie Sbong, Department of Biological Sciences, College of Arts and Sciences & Honors College Dr. Edward Dzialowski, Department of Biological Sciences, College of Arts and Sciences

2. Lab Goals To understand the development of human respiratory and cardiovascular systems using avian models ◦ To characterize the ductus arteriosi in chicken embryos

3. Mammalian Ductus Arteriosus Fetal Circulatory System Vessel that connects pulmonary artery with aorta Shunts blood away from lungs  to body Closes upon birth Randell et al., 2002 Circulation In Womb

4. Avian Ductus Arteriosi Notice: ◦ Aorta branches left, not right. ◦ Two longer ductus arteriosi rpa to lung lpa to lung aorta pa LDA RDA rv da lv to body and CAM

5. Lab Goals To understand the development of human respiratory and cardiovascular systems using avian models ◦ To characterize the ductus arteriosi in chicken embryos

6. Focus How does O 2 uptake at the CAM and interact during internal pipping? How does CO 2 uptake at the CAM and lungs interact during internal pipping?

7. Rahn, Ar, Paganelli. “How Bird Eggs Breathe” 1979

8. Pre-pippedInternally Pipped CAMCAM + Lungs 12% O 2 5% CO 2

9. Rahn, Ar, Paganelli. “How Bird Eggs Breathe” 1979

10. Focus How does O 2 uptake at the CAM and interact during internal pipping? How does CO 2 uptake at the CAM and lungs interact during internal pipping?

11. Lung and CAM Respiration Air Cell Gas Mixture 12% O 2, 5% CO 2, 83% N 2 Egg Air Measure lung and CAM oxygen consumption separately Open flow respirometry

12. Air cell Respirometer

13. O 2 Level of Exposure Egg O 2 Air Cell O 2 21% 5% 15%12% 15%21% 15%5% 30%12% 30%21% 30%5% Egg O 2 Air Cell O 2 21%12% CONTROL TESTING

14. Lung metabolic rate vs. total metabolic rate at normoxia

15. Results There was a positive correlation between Vo 2 lungs and Vo 2 total.

16. Lung metabolic rate vs. total metabolic rate

17. Results There was a positive correlation between Vo 2 lungs and Vo 2 total. Different stages of internal pipping

18. Changes in Lung MR vs. changes in CAM MR

20. Results Embryos have the ability to use the CAM or lungs to compensate for each other. Significance: ◦ CAM hyperoxic, lungs hypooxic  increased VO 2 total ◦ Both CAM and lungs are hypoxic  both decrease Could response be due to changes in ventilation patterns?

21. AC 5% O 2 AC 21% O 2 AC 2.5% CO 2 Tidal volume Frequency 103 ± 6 96 ± 755 ± 6 * 103 ± 3 105 ± 696 ± 7 Changes in ventilation after changing air cell O 2 and CO 2 Data presented as % of control Pulmonary ventilation 107 ± 8101 ± 951 ± 6 *

22. Ventilation At internal pipping: ◦ Ventilatory oxygen chemosensitivity has little role in controlling O 2 exchange ◦ Develops during external pipping ◦ CO 2 chemosensitivity is functioning  in ventilation plays no role in controlling gas exchange in response to hypoxia or hypoeroxia

23. Blood Flow Dr. Dzialowski, Upward Bound Students Microspheres Technique

24. * * * Repeated Measures ANOVA CAM p = 0.013 Brain p = 0.001 Hypoxia

25. * * * Repeated Measures ANOVA CAM p = 0.024 Brain p = 0.26 Hyperoxia

26. Results Lung hypoxia  increased blood flow through the ductus arteriosi Lung hyperoxia  decreased blood flow through the ductus arteriosi Achieved by altering blood flow to the lungs and through the ductus arteriosi and the interatrial foramina

27. Focus How does O 2 uptake at the CAM and interact during internal pipping? How does CO 2 uptake at the CAM and lungs interact during internal pipping?

28. CO 2 Level of Exposure Egg CO 2 Air Cell CO 2 0% 2.5% 0%10% 5% Egg CO 2 Air Cell CO 2 0%5% CONTROL TESTING

29. Changes in Lung MR vs. changes in CAM MR

30. Results Lung hypercapnia  no change VO 2 total Lung hypocapnia  decreasing VO2total Egg hypercapnia  increase both VO 2 total Brain senses CO 2 levels (carbon dioxide chemosensitivity)

31. Final Conclusions During internal pipping, chicken embryos have two sites of respiration: CAM and air cell. When there is a change in oxygen level at one respiration site, the other site compensates. ◦ Blood flow is the compensation mechanism for O 2 changes. O 2 chemosensitivity in the IP chicken embryo is weak and developing, while CO 2 chemosensitivity is functional.

32. Future Research Measure ventilation and blood flow patterns during hypercapnia and hypocapnia

33. QUESTIONS?

34. Acknowledgments Dr. Dzialowski, Faculty Mentor Dr. Eve and Dr. Cox, Honors College Upward Bound Students: ◦ Miguel Cavazos ◦ Felicia Guerrero ◦ Heather Morgan