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  • Canadian Science Publishing  (4)
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  • Canadian Science Publishing  (4)
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  • 1
    Online Resource
    Online Resource
    Canadian Science Publishing ; 1977
    In:  Canadian Journal of Zoology Vol. 55, No. 12 ( 1977-12-01), p. 2024-2034
    In: Canadian Journal of Zoology, Canadian Science Publishing, Vol. 55, No. 12 ( 1977-12-01), p. 2024-2034
    Abstract: Pulmonary ventilation and perfusion have been measured directly in unanaesthetized turtles (Pelomedusa subrufa) and tortoises (Testudo pardalis) during normal air breathing and during the inspiration of both hypoxic and hypercapnic gases. Lung ventilation in air was intermittent in both species and particularly in the turtle was accompanied by transient increases in pulmonary perfusion. Hypercapnia (4% CO 2 in air) elicited a twofold to threefold increase in pulmonary perfusion but a sixfold increase in pulmonary ventilation in both species. Consequently the ventilation:perfusion ratio more than doubled in value. Unlike the hypercapnic responses, hypoxia (5% O 2 in N 2 ) increased pulmonary perfusion by two to five times but increased pulmonary ventilation by less than two times, and so the ventilation:perfusion ratio fell by one-half during hypoxic exposure. These data are interpreted in terms of intermittent breathing and processes of O 2 and CO 2 transport.
    Type of Medium: Online Resource
    ISSN: 0008-4301 , 1480-3283
    RVK:
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1977
    detail.hit.zdb_id: 1490831-1
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Canadian Science Publishing ; 1979
    In:  Canadian Journal of Zoology Vol. 57, No. 12 ( 1979-12-01), p. 2331-2336
    In: Canadian Journal of Zoology, Canadian Science Publishing, Vol. 57, No. 12 ( 1979-12-01), p. 2331-2336
    Abstract: Male Sepia officinalis were subjected to hypoxia and the concentrations of blood metabolites were measured during stress and recovery. Blood octopine levels were elevated during hypoxia, whereas blood glucose concentration declined. During recovery, octopine was rapidly cleared from the blood while blood glucose concentration increased, initially overshooting the control level, before returning to prehypoxia levels.The clearance of an octopine bolus (300 μmol given intravenously) from the blood was followed. Octopine uptake from the blood was correlated with a transient rise in blood glucose concentration. Injection of an arginine bolus resulted in an increase in blood octopine levels, whereas a lactate bolus led to elevated blood glucose and octopine levels.The data show that octopine concentration in cephalopod blood is modulated in response to physiological stress and that octopine metabolism is closely integrated with the metabolism of glucose, arginine, and lactate. It is suggested that the octopine produced during glycolytic muscular work is transported via the bloodstream for use as an aerobic substrate in other tissues. The inverse relationship between blood octopine and glucose levels suggests the presence of a modified "Cori cycle" in which octopine released from muscle can be taken up by tissues capable of utilizing the compound as a gluconeogenic substrate.
    Type of Medium: Online Resource
    ISSN: 0008-4301 , 1480-3283
    RVK:
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1979
    detail.hit.zdb_id: 1490831-1
    SSG: 12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Canadian Science Publishing ; 1985
    In:  Canadian Journal of Zoology Vol. 63, No. 4 ( 1985-04-01), p. 821-823
    In: Canadian Journal of Zoology, Canadian Science Publishing, Vol. 63, No. 4 ( 1985-04-01), p. 821-823
    Abstract: Zoarces viviparous were maintained in either normoxic or hypoxic ([Formula: see text], 4–4.7 kPa) water for 4–6 weeks. The hypothesis that adaptation to hypoxia results in an increase in the potential for anaerobic energy production in heart was tested. There was no difference in the activities of key enzymes of energy metabolism or in the content of myoglobin between the hearts from control or experimental fish. However, ventricular strips from animals adapted to hypoxic conditions were better able to sustain tension development than hearts from control animals during anoxia in the presence of high levels of external Ca 2+ . A combination of high Ca 2+ and glucose was particularly effective in improving performance. The data suggest that hypoxic adaptation leads to an enhancement of Ca 2+ -activated carbohydrate mobilization but that the enzyme complement required to process the additional glycolytic flux is already in place.
    Type of Medium: Online Resource
    ISSN: 0008-4301 , 1480-3283
    RVK:
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1985
    detail.hit.zdb_id: 1490831-1
    SSG: 12
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    Canadian Science Publishing ; 1970
    In:  Journal of the Fisheries Research Board of Canada Vol. 27, No. 3 ( 1970-03-01), p. 551-564
    In: Journal of the Fisheries Research Board of Canada, Canadian Science Publishing, Vol. 27, No. 3 ( 1970-03-01), p. 551-564
    Abstract: Unanesthetized specimens of Pacific dogfish, Squalus suckleyi, were used to study the relationships of oxygen uptake to ventilation and blood perfusion of the gills. Ventilation–perfusion ratios [Formula: see text] were determined over a wide range.In resting dogfish the [Formula: see text] ratios normally fell within the range of 10–20 at 6–10 C with a ventilation usually between 200 and 500 ml/min∙kg and a cardiac output between 20 and 40 ml/min∙kg. The extraction of oxygen from water varied from about 20 to 50% within that [Formula: see text] range, but at lower ratios the extraction was higher and sometimes exceeded 75%. When extraction was high the oxygen tension of expired water often fell below that of arterial blood thus indicating countercurrent gas exchange.The oxygen uptake varied almost directly with cardiac output over a wide range and with ventilation at low and normal water flows.Data are presented regarding the effectiveness of oxygen removal from water, oxygen uptake by blood, and overall transfer of oxygen from water to blood at various ventilations.In curarized dogfish the heart rate varied with changes of induced ventilation. The reflex nature of this cardiac and ventilatory coupling was revealed by its abolition when the fish were atropinized.
    Type of Medium: Online Resource
    ISSN: 0015-296X
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1970
    detail.hit.zdb_id: 3036-3
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