Journal of Comparative Physiology B

, Volume 184, Issue 5, pp 641–649 | Cite as

Dynamics of acid–base metabolic compensation and hematological regulation interactions in response to CO2 challenges in embryos of the chicken (Gallus gallus)

Original Paper


CO2 exposure elicits multiple changes in the acid–base balance and hematology of avian embryos, but the time-specific, dose-dependent effects of graded increases in extrinsic CO2 in a normoxic environment are poorly understood. Consequently, we exposed day 15 chicken embryos to 1, 3, 5, 6 or 10 % CO2 in 20 % O2. We hypothesized that both the magnitude of hypercapnic respiratory acidosis and the resultant metabolic compensation within 24 h of exposure to <10 % CO2 are proportional to ambient CO2 concentration ([CO2]). We also predicted that regulation of hematological respiratory variables is graded according to [CO2]. Time-course (2, 6 and 24 h) changes were determined for acid–base disturbances and hematological respiratory variables; hematocrit (Hct), red blood cell concentration ([RBC]), hemoglobin concentration, mean corpuscular volume (MCV) and other mean corpuscular indices. Both the decrease in uncompensated pH, which indicates uncompensated respiratory acidosis, and the compensatory pH increase, a sign of metabolic compensation, increased with [CO2]. The partial metabolic compensation across all CO2 gas mixtures was ~17, 46 and 53 % compensation at 2, 6 and 24 h, respectively. Hematological responses were nearly identical across the entire range of [CO2], with Hct decreasing across the time course of CO2 exposure due to a decrease in MCV from 2 to 24 h and a decrease in [RBC] at 24 h. Even though hematological regulation was not graded, chicken embryos were able to compensate and survive exposure to <10 % CO2.


Chicken embryo Acid–base balance Hematological respiratory variables Hypercapnia Metabolic compensation Respiratory acidosis 





Red blood cell concentration


Mean corpuscular volume


Hemoglobin concentration


Mean corpuscular hemoglobin


Mean corpuscular hemoglobin concentration


Carbon dioxide concentration


Oxygen concentration


Arterialized blood carbon dioxide partial pressure


Arterialized blood pH


Arterialized blood bicarbonate concentration


Blood osmolality


Change in pH


Change in blood bicarbonate concentration


Percent change in hematocrit


Percent change in red blood cell concentration


Percent change in mean corpuscular volume



Support for this study was provided by NSF operating Grant IOS-1025823 to Warren W. Burggren.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Casey Mueller
    • 1
    • 2
  • Hiroshi Tazawa
    • 1
  • Warren Burggren
    • 1
  1. 1.Developmental Integrative Biology, Department of Biological SciencesUniversity of North TexasDentonUSA
  2. 2.Department of BiologyMcMaster UniversityHamiltonCanada

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