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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
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Lab Goals To understand the development of human respiratory and cardiovascular systems using avian models ◦ To characterize the ductus arteriosi in chicken embryos
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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
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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
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Lab Goals To understand the development of human respiratory and cardiovascular systems using avian models ◦ To characterize the ductus arteriosi in chicken embryos
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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?
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Rahn, Ar, Paganelli. “How Bird Eggs Breathe” 1979
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Pre-pippedInternally Pipped CAMCAM + Lungs 12% O 2 5% CO 2
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Rahn, Ar, Paganelli. “How Bird Eggs Breathe” 1979
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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?
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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
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Air cell Respirometer
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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
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Lung metabolic rate vs. total metabolic rate at normoxia
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Results There was a positive correlation between Vo 2 lungs and Vo 2 total.
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Lung metabolic rate vs. total metabolic rate
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Results There was a positive correlation between Vo 2 lungs and Vo 2 total. Different stages of internal pipping
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Changes in Lung MR vs. changes in CAM MR
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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?
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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 *
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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
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Blood Flow Dr. Dzialowski, Upward Bound Students Microspheres Technique
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* * * Repeated Measures ANOVA CAM p = 0.013 Brain p = 0.001 Hypoxia
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* * * Repeated Measures ANOVA CAM p = 0.024 Brain p = 0.26 Hyperoxia
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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
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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?
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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
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Changes in Lung MR vs. changes in CAM MR
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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)
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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.
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Future Research Measure ventilation and blood flow patterns during hypercapnia and hypocapnia
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QUESTIONS?
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Acknowledgments Dr. Dzialowski, Faculty Mentor Dr. Eve and Dr. Cox, Honors College Upward Bound Students: ◦ Miguel Cavazos ◦ Felicia Guerrero ◦ Heather Morgan
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