Ontogeny of acid-base balance in the bullfrog and chicken

Erasmus, Beth de W.; Howell, B.J.; Rahn, Hermann

doi:10.1016/0034-5687(70)90101-5

Cited by 69 publications

(15 citation statements)

References 15 publications

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“…Furthermore, embryos encapsulated within extra-embryonic structures (e.g. eggshells) face additional restrictions on the diffusion of O 2 and CO 2 (Goldberg et al, 2008;Tazawa, 1980), which makes the exchange of gases and acid-base equivalents with the environment challenging and limits the ability of the embryo to undergo coupled pH regulation (Erasmus et al, 1971). Although turtles and alligators appear to lose the capacity for preferential pH i regulation as adults, a number of adult fishes and an aquatic salamander preferentially regulate pH i (Fig.…”

Section: Preferential Ph I Regulation During Developmentmentioning

confidence: 99%

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 Developmentmentioning

confidence: 99%

Preferential intracellular pH regulation: hypotheses and perspectives

Shartau

Baker

Crossley

et al. 2016

Journal of Experimental Biology

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“…However, cardiac function in embryos at 90% of incubation was not preserved. The difference in cardiac function between developmental ages may be due to the increased metabolic demand of older embryos being depressed by changes in CO 2 and O 2 (Erasmus et al, 1971), as in adult turtles cardiac function is reduced during periods of lower metabolic demand (Jackson, 1987;Jackson et al, 1991).…”

Section: Cardiovascular Function May Be Protected By Preferential Ph mentioning

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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“…These tren ds have been do cumented by several groups (51, 60,72 increase in buffering cap acity associated with increased concentrations of hemo globin in the bloo d (6 0). These tren ds have been do cumented by several groups (51, 60,72 increase in buffering cap acity associated with increased concentrations of hemo globin in the bloo d (6 0).…”

Section: Respira Tion Of Birds Prior To Hatchingmentioning

confidence: 79%

Avian Physiology

Dawson¹

1975

Annu. Rev. Physiol.

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Research on the physiology of birds has grown enormou sly in recent years. Much of thi s g rowth is, of course, a manifestation of the importance of certain domesti cated species in food production, and some of it also reflects the suitability of certain birds as experimental subjects in some types of physiological investigations. How ever, it also is a testimonial to the fact that birds are inherently interesting animals with frequently elaborate behaviors, spectacular powers of locomotion, and impres sive regulatory cap acities. Their evolution from a reptilian stock quite distinct from th at giving rise to their fellow homeotherms, the mammal s, makes consideration of certain of the se regul atory cap acitie s intriguing from a comparative standpoint.Variou s facets of avian phy siology have been extensively tr eated in monographs, symposia, and review articles or chapters over the past fi ve years. The volumes of Avian Biology (64) represent a particularly useful source of information. With this wealth of material available, and considering limitations of sp ace, it seems appropri ate in this article to adopt an eclectic approach. The topics selected for discu ssion should provide a basis for examining the ways in which birds resemble or differ from other vertebrates, especially mammals, in the means by which they meet common functional requirements. SOME ENERGETIC CONSIDERATIONSMost aspects of avian physiology considered here are directly related to energetics or th e consequence s of catabolic processes, and it is thus pertinent to include a few statements on metabolic rates of birds. These rates tend to vary with a fractional power of body mass, as in most animals. Earlier analyses (29, 95) suggested that the exponent in the allometric equation relating basal metabolic rate (BMR) to body mass was lower than that reported for eutherian mammals (98). Subsequently, this was shown to be an arti fact of lumping data for order s of bird s differing substanti ally in metabolic level (107). When the data are an alyzed properly an exponent near 0.75 is obtained. This is of intere st in view of a recent analy sis of physiological sc aling 1

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Ontogeny of acid-base balance in the bullfrog and chicken

Cited by 69 publications

References 15 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

Avian Physiology

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