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  • 1
    ISSN: 1432-136X
    Keywords: Heart rate ; Temperature ; Reptile development ; Embryo ; Turtle,Chelydra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Growth and development can occur over a wide range of physical conditions in reptiles. Cardiovascular function must be critical to this ability. However, information on cardiovascular function in developing oping reptiles is lacking. Previous work indicated that in reptiles the effects of temperature on growth and metabolism are largely restricted to early development. This study examined whether the previously observed effects of temperature and different perinatal patterns of metabolism observed in amniotic vertebrates are correlated with cardiovascular function. Embryonic and hatchling carcass mass, heart mass and heart rate (HR) were compared for snapping turtle eggs (Chelydra serpentina) incubated at 24° and 29°C. Incubation time was shorter at 29 °C (56.2 days) than at 24 °C (71:1 days). Carcass and heart growth showed a sigmoidal pattern at both temperatures. However, cardiac growth showed a relative decrease as incubation proceeded. Incubation temperature significantly affected the HR pattern during development. The HR of embryos incubated at 24 °C was constant for most of incubation (51.8±4.8 min-1). A small decrease was observed just prior to and a large decrease immediately following hatching (posthatch, 22.3±4.1 min-1). At 29 °C embryonic HR was greater than at 24 °C early in development (72.3±3 min-1). The HR steadily decreased to values equivalent to those at 24 °C. The HRs of 24 °C and 29 °C hatchlings were not different. Cardiac output (estimated as the product of heart mass and HR) increased rapidly during early development and then slowed dramatically at both temperatures. These data are consistent with the suggestion that temperature exerts its effects primarily early in development. Furthermore, the changes in cardiovascular function are correlated with metabolic changes in hatching vertebrates.
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  • 2
    ISSN: 1432-136X
    Keywords: Key words Heart rate ; Temperature ; Reptile development ; Embryo ; Turtle ; Chelydra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Growth and development can occur over a wide range of physical conditions in reptiles. Cardiovascular function must be critical to this ability. However, information on cardiovascular function in developing reptiles is lacking. Previous work indicated that in reptiles the effects of temperature on growth and metabolism are largely restricted to early development. This study examined whether the previously observed effects of temperature and different perinatal patterns of metabolism observed in amniotic vertebrates are correlated with cardiovascular function. Embryonic and hatchling carcass mass, heart mass and heart rate (HR) were compared for snapping turtle eggs (Chelydra serpentina) incubated at 24 ° and 29 °C. Incubation time was shorter at 29 °C (56.2 days) than at 24 °C (71.1 days). Carcass and heart growth showed a sigmoidal pattern at both temperatures. However, cardiac growth showed a relative decrease as incubation proceeded. Incubation temperature significantly affected the HR pattern during development. The HR of embryos incubated at 24 °C was constant for most of incubation (51.8±4.8 min-1). A small decrease was observed just prior to and a large decrease immediately following hatching (posthatch, 22.3±4.1 min-1). At 29 °C embryonic HR was greater than at 24 °C early in development (72.3±3 min-1). The HR steadily decreased to values equivalent to those at 24 °C. The HRs of 24 °C and 29 °C hatchlings were not different. Cardiac output (estimated as the product of heart mass and HR) increased rapidly during early development and then slowed dramatically at both temperatures. These data are consistent with the suggestion that temperature exerts its effects primarily early in development. Furthermore, the changes in cardiovascular function are correlated with metabolic changes in hatching vertebrates.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-136X
    Keywords: Key words Cardiovascular ; Hypoxia ; Crustacea ; Respiratory ; Doppler
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The heart rate of crayfish (Procambarus clarkii) and lobsters (Homarus americanus) decreased (bradycardia) as partial pressure of O2 (P O 2) decreased, yet cardiac output (V b) was maintained via an increased stroke volume (S v) to P O 2s of 40 mmHg and 75 mmHg for crayfish and lobsters, respectively. V b was redistributed in both animals. Flow through the anterior aorta increased while flow dropped through the posterior aorta and sternal artery to a P O 2 of 30 mmHg; below this flow was no longer maintained in crayfish. In the lobster, flow increased to the lateral arteries and the ventral thoracic artery while flow through the anterior and posterior aortas, sternal artery and ventral abdominal artery decreased to a P O 2 of 75 mmHg. Anterior hemolymph flow was maintained or increased in both animals presumably to supply nervous tissue and cephalic sense organs better. Crayfish showed an increase in intracardiac and mean arterial hemolymph pressures as P O 2 declined. The increased pressures combined with the net increase in cardiac filling pressure and diastolic filling time could have accounted for the increased S V. The cardiovascular response exhibited by both the crayfish and lobster was P O 2 dependent; below a critical water P O 2 active compensation was no longer observed.
    Type of Medium: Electronic Resource
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