Interactions of acid–base balance and hematocrit regulation during environmental respiratory gas challenges in developing chicken embryos (Gallus gallus)

Burggren, Warren W.; Andrewartha, Sarah J.; Tazawa, Hiroshi

doi:10.1016/j.resp.2012.06.011

Cited by 20 publications

(17 citation statements)

References 63 publications

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“…Exposing chicken embryos in vivo to severe acute respiratory or metabolic acidosis for up to 24 h results in large reductions in pH e that are not fully compensated, but the embryos survive (Burggren et al, 2012;Mueller et al, 2014) -a pattern that is consistent with the pH e changes observed in fish that preferentially regulate pH i ). These studies did not measure pH i ; however, based on these data, we hypothesize that embryonic chickens may preferentially regulate pH i , making this a potential avian model that is clearly worthy of study.…”

Section: Preferential Ph I Regulation During Developmentsupporting

confidence: 60%

Preferential intracellular pH regulation: hypotheses and perspectives

Shartau

Baker

Crossley

et al. 2016

Journal of Experimental Biology

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The regulation of vertebrate acid-base balance during acute episodes of elevated internal P CO2 is typically characterized by extracellular pH ( pH e ) regulation. Changes in pH e are associated with qualitatively similar changes in intracellular tissue pH ( pH i ) as the two are typically coupled, referred to as 'coupled pH regulation'. However, not all vertebrates rely on coupled pH regulation; instead, some preferentially regulate pH i against severe and maintained reductions in pH e . Preferential pH i regulation has been identified in several adult fish species and an aquatic amphibian, but never in adult amniotes. Recently, common snapping turtles were observed to preferentially regulate pH i during development; the pattern of acid-base regulation in these species shifts from preferential pH i regulation in embryos to coupled pH regulation in adults. In this Commentary, we discuss the hypothesis that preferential pH i regulation may be a general strategy employed by vertebrate embryos in order to maintain acid-base homeostasis during severe acute acid-base disturbances. In adult vertebrates, the retention or loss of preferential pH i regulation may depend on selection pressures associated with the environment inhabited and/or the severity of acid-base regulatory challenges to which they are exposed. We also consider the idea that the retention of preferential pH i regulation into adulthood may have been a key event in vertebrate evolution, with implications for the invasion of freshwater habitats, the evolution of air breathing and the transition of vertebrates from water to land.

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Section: Preferential Ph I Regulation During Developmentsupporting

confidence: 60%

Preferential intracellular pH regulation: hypotheses and perspectives

Shartau

Baker

Crossley

et al. 2016

Journal of Experimental Biology

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“…Chicken embryos between 60% and 90% of incubation subjected to hypercarbia (5 kPa P CO2 ) for 24 h experienced a reduction in pH e that was largely uncompensated (Burggren et al, 2012). Embryonic chickens are exceptionally hypercarbia tolerant as they can survive 1 h exposure to P CO2 of 10 kPa where pH e is reduced by ∼0.8 pH units (Andrewartha et al, 2014), a degree of pH e depression typically observed in animals that preferentially regulate pH i .…”

Section: Introductionmentioning

confidence: 99%

Embryonic common snapping turtles (Chelydra serpentina) preferentially regulate intracellular tissue pH during acid-base challenges

Shartau

Crossley

Kohl

et al. 2016

Journal of Experimental Biology

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The nests of embryonic turtles naturally experience elevated CO 2 (hypercarbia), which leads to increased blood P CO2 and a respiratory acidosis, resulting in reduced blood pH [extracellular pH ( pH e )]. Some fishes preferentially regulate tissue pH [intracellular pH ( pH i )] against changes in pH e ; this has been proposed to be associated with exceptional CO 2 tolerance and has never been identified in amniotes. As embryonic turtles may be CO 2 tolerant based on nesting strategy, we hypothesized that they preferentially regulate pH i , conferring tolerance to severe acute acid-base challenges. This hypothesis was tested by investigating pH regulation in common snapping turtles (Chelydra serpentina) reared in normoxia then exposed to hypercarbia (13 kPa P CO2 ) for 1 h at three developmental ages: 70% and 90% of incubation, and yearlings. Hypercarbia reduced pH e but not pH i , at all developmental ages. At 70% of incubation, pH e was depressed by 0.324 pH units while pH i of brain, white muscle and lung increased; heart, liver and kidney pH i remained unchanged. At 90% of incubation, pH e was depressed by 0.352 pH units but heart pH i increased with no change in pH i of other tissues. Yearlings exhibited a pH e reduction of 0.235 pH units but had no changes in pH i of any tissues. The results indicate common snapping turtles preferentially regulate pH i during development, but the degree of response is reduced throughout development. This is the first time preferential pH i regulation has been identified in an amniote. These findings may provide insight into the evolution of acid-base homeostasis during development of amniotes, and vertebrates in general.

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“…Control [La − ] in chicken embryos is relatively low, ranging from 0.5 to 1.5 mmol L −1 in a normoxic environment (Freeman, 1965;Tazawa et al, 1983bTazawa et al, , 2012Tazawa, 1986;Bjǿnnes et al, 1987;Høiby et al, 1987;Burggren et al, 2012;present study). However, when O 2 supply to the tissues is deficient, [La − ] increases markedly due to anaerobic glycolysis.…”

Section: Lactate Concentrationmentioning

confidence: 75%

“…Therefore, in general, it is presumed that avian embryos should be able to demonstrate a high tolerance to hypercapnic environments. Indeed, exposures to 5-20% CO 2 has been used as an investigative tool in studies of reserve capacity of physiological functions of late chicken embryos (Dawes and Simkiss, 1971;Tazawa, 1981;Andrewartha et al, 2011;Burggren et al, 2012;Tazawa et al, 2012;Mueller et al, 2013Mueller et al, , 2014b. Unlike respiratory acidosis experienced in tions efficiently for embryos if they are exposed to ≤10% CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Hypercapnic thresholds for embryonic acid–base metabolic compensation and hematological regulation during CO2 challenges in layer and broiler chicken strains

Burggren

Mueller

Tazawa

2015

Respiratory Physiology & Neurobiology

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Time specific acid-base metabolic compensation and responses of hematological respiratory variables were measured in day 15 layer (Hyline) and broiler (Cornish Rock) chicken embryos during acute hypercapnic challenges (3, 6, 10 and 20% CO2). Control acid-base status and hematology differed between two strains. Broiler embryos were relatively respiratory acidotic and had higher hematocrit (Hct) and hemoglobin concentration. The partial metabolic compensation for respiratory acidosis produced by ≤ 10% CO2 exposures occurred in proportion to CO2 concentrations in both strains, but metabolic compensation for 20% CO2 respiratory acidosis was depressed at 2, 6 and 24h, particularly in broiler embryos. Exposure to ≤ 10% CO2 induced the same hematological responses across CO2 concentrations; i.e., Hct and mean corpuscular volume (MCV) increased while RBC concentration remained unchanged. In response to 20% CO2 exposure, Hct and MCV increased dramatically in both stains. Consequently, altered acid-base and hematology responses to 20% CO2 exposure compared to ≤ 10% CO2 suggest that the hypercapnic threshold to compensation for acidosis and regulation of hematology is >10% CO2.

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Interactions of acid–base balance and hematocrit regulation during environmental respiratory gas challenges in developing chicken embryos (Gallus gallus)

Cited by 20 publications

References 63 publications

Preferential intracellular pH regulation: hypotheses and perspectives

Preferential intracellular pH regulation: hypotheses and perspectives

Embryonic common snapping turtles (Chelydra serpentina) preferentially regulate intracellular tissue pH during acid-base challenges

Hypercapnic thresholds for embryonic acid–base metabolic compensation and hematological regulation during CO2 challenges in layer and broiler chicken strains

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