Chronic hypoxic hypercapnia modifies in vivo and in vitro ventilatory chemoreflexes in the cane toad

Srivaratharajah, Kajapiratha; Cui, Alex; McAneney, Jessica; Reid, Scott D.

doi:10.1016/j.resp.2007.10.007

Cited by 3 publications

(3 citation statements)

References 35 publications

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“…Amphibians, and cane toads in particular, have well-developed physiological capacities to survive in low oxygen or anoxic environments [ 16 ]. In addition, they have physiological capabilities to deal with increasing levels of CO 2 in the blood stream and can shunt CO 2 into other tissues for short-term storage or excrete it via their skin [ 17 ].…”

Section: Methodsmentioning

confidence: 99%

An Efficient Method for the Euthanasia of Cane Toads (Rhinella marina) under Northern Australian Field Conditions

Kay

Mawson

2021

Animals

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The euthanasia of cane toads under field conditions presents a number of logistical and animal welfare challenges. One recommended method of control involves the use of carbon dioxide in plastic bags. This paper describes the minimum amount of time (4 h) required to efficiently euthanase toads with a carbon dioxide concentration of 4.96% under field conditions experienced in northern Australia. Discussion is also provided on the issues of safe disposal of biological and plastic waste associated with the application of this method.

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Section: Methodsmentioning

confidence: 99%

An Efficient Method for the Euthanasia of Cane Toads (Rhinella marina) under Northern Australian Field Conditions

Kay

Mawson

2021

Animals

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“…The latter was abolished by midbrain transection, again illustrating a descending inhibitory role of higher brain structures on ventilatory activity produced by the medulla (McAneney and Reid 2007). Chronic exposure to hypoxic hypercapnia (10% O 2 /3.5% CO 2 ), also blunted the ventilatory response to hypoxia in intact animals (Srivaratharajah et al 2008). In isolated brainstems from these toads, respiratory frequency was augmented due to an increase in the number of breathing episodes/minute (Srivaratharajah et al 2008).…”

Section: Amphibiansmentioning

confidence: 99%

“…Chronic exposure to hypoxic hypercapnia (10% O 2 /3.5% CO 2 ), also blunted the ventilatory response to hypoxia in intact animals (Srivaratharajah et al 2008). In isolated brainstems from these toads, respiratory frequency was augmented due to an increase in the number of breathing episodes/minute (Srivaratharajah et al 2008). Overall these results indicate that anuran amphibians do not exhibit ventilatory acclimatization to hypoxia, as seen in some fish and mammals, although it is clear that prolonged hypoxic (and hypercapnic) exposure modifies the ventilatory responses to subsequent exposures to hypoxia, indicating that respiratory plasticity does occur in anurans.…”

Section: Amphibiansmentioning

confidence: 99%

Time domains of the hypoxic ventilatory response in ectothermic vertebrates

et al. 2011

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Over a decade has passed since Powell et al. (Respir Physiol 112:123–134, 1998) described and defined the time domains of the hypoxic ventilatory response (HVR) in adult mammals. These time domains, however, have yet to receive much attention in other vertebrate groups. The initial, acute HVR of fish, amphibians and reptiles serves to minimize the imbalance between oxygen supply and demand. If the hypoxia is sustained, a suite of secondary adjustments occur giving rise to a more long-term balance (acclimatization) that allows the behaviors of normal life. These secondary responses can change over time as a function of the nature of the stimulus (the pattern and intensity of the hypoxic exposure). To add to the complexity of this process, hypoxia can also lead to metabolic suppression (the hypoxic metabolic response) and the magnitude of this is also time dependent. Unlike the original review of Powell et al. (Respir Physiol 112:123–134, 1998) that only considered the HVR in adult animals, we also consider relevant developmental time points where information is available. Finally, in amphibians and reptiles with incompletely divided hearts the magnitude of the ventilatory response will be modulated by hypoxia-induced changes in intra-cardiac shunting that also improve the match between O2 supply and demand, and these too change in a time-dependent fashion. While the current literature on this topic is reviewed here, it is noted that this area has received little attention. We attempt to redefine time domains in a more ‘holistic’ fashion that better accommodates research on ectotherms. If we are to distinguish between the genetic, developmental and environmental influences underlying the various ventilatory responses to hypoxia, however, we must design future experiments with time domains in mind.

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Adenosine A2A receptor deficiency prevents p38MAPK activation and apoptosis of mouse hippocampal cells in the chronic hypoxic-hypercapnia model

Ren

Guo

Wang

et al. 2019

Bioscience, Biotechnology, and Biochemistry

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This study aims to study the effects of adenosine A2A receptor (A2AR) on hippocampal cell apoptosis and the putative mechanisms in a mouse model of chronic hypoxic-hypercapnia. Wild-type (WT) or A2AR knockout (A2AR KO) mice were randomly divided into normal control (NC) groups and chronic hypoxic-hypercapnia (4HH) groups. Compared with their corresponding NC groups (WT-NC and KO-NC), the apoptosis index (AI), caspase-3 activity, Bax mRNA and P-p38 protein expression in the hippocampus of 4HH groups (WT-4HH and KO-4HH) were significantly increased, while Bcl2 mRNA expression was significantly decreased (P < 0.05). Moreover, A2AR deficiency significantly rescued the effect of chronic hypoxic-hypercapnia on apoptosis when compared with the WT-4HH group (P < 0.05). A2AR deficiency inhibits hippocampal cell apoptosis in mice exposed to chronic hypoxic-hypercapnia, which might be associated with dampened p38 MAPK activation and Bax mRNA expression, and augmented Bcl-2 mRNA expression.

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Chronic hypoxic hypercapnia modifies in vivo and in vitro ventilatory chemoreflexes in the cane toad

Cited by 3 publications

References 35 publications

An Efficient Method for the Euthanasia of Cane Toads (Rhinella marina) under Northern Australian Field Conditions

An Efficient Method for the Euthanasia of Cane Toads (Rhinella marina) under Northern Australian Field Conditions

Time domains of the hypoxic ventilatory response in ectothermic vertebrates

Adenosine A2A receptor deficiency prevents p38MAPK activation and apoptosis of mouse hippocampal cells in the chronic hypoxic-hypercapnia model

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