Combined ventilatory responses to aerial hypoxia and temperature in the South American lungfish Lepidosiren paradoxa

Silva, Glauber S. F. da; Giusti, Humberto; Branco, Luiz G.S.; Glass, Mogens L.

doi:10.1016/j.jtherbio.2011.09.004

Cited by 9 publications

(9 citation statements)

References 28 publications

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“…Ventilation and gas exchange was measured following Glass et al (1978b), Wang and Warburton (1995) and Silva et al (2011). Feeding was suspended seven days before experimentation.…”

Section: Setupmentioning

confidence: 99%

Ventilation and gas exchange in two turtles: Podocnemis unifilis and Phrynops geoffroanus (Testudines: Pleurodira)

Cordeiro

Abe

Klein

2016

Respiratory Physiology & Neurobiology

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Turtles (Testudines) have two major taxa, Pleurodira and Cryptodira. To date, only limited data are available regarding the respiratory physiology of pleurodirans. To begin to address this, we studied ventilation and gas exchange in Podocnemis unifilis and Phrynops geoffroanus. Breathing pattern in both species could be described as episodic with breathing episodes separated by large non-ventilatory periods. We measured duration of inspiration and expiration, breathing frequency, duration of the non-ventilatory period (time between episodes), tidal volume, and oxygen consumption when breathing normoxia, hypoxia and hypercarbia at 25°C. In both species hypercarbia caused a greater increase in ventilation compared to hypoxia, increasing both breathing frequency and tidal volume. Minute ventilation and oxygen consumption in P. geoffroanus were the lowest described so far in testudines, indicating either extra-pulmonary gas exchange or a significantly lower metabolism. Oxidative costs of breathing, estimated using the regression method, was the highest described so far for any reptile. Further studies are necessary to better understand respiratory physiology in Phrynops and Podocnemis species.

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“…Ventilation and gas exchange was measured following Glass et al (1978b), Wang and Warburton (1995) and Silva et al (2011). Feeding was suspended seven days before experimentation.…”

Section: Setupmentioning

confidence: 99%

Ventilation and gas exchange in two turtles: Podocnemis unifilis and Phrynops geoffroanus (Testudines: Pleurodira)

Cordeiro

Abe

Klein

2016

Respiratory Physiology & Neurobiology

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“…This response is evidenced by a significant increase in air convection requirement for oxygen at both temperatures. It was shown in a previous study (da Silva et al, 2011) that the magnitude of the ventilatory response is highly temperaturedependent in L. paradoxa, which may be of adaptive importance for an animal that experiences large seasonal variations in its habitat, such as drought and environmental temperature fluctuations. Moreover, integrated cardiorespiratory responses are expected in the O 2 -cascade under conditions of increased O 2 demand.…”

Section: Discussionmentioning

confidence: 97%

“…These data were reported for animals exposed to aerial/aquatic normoxic environment. Da Silva et al (2011) studied interactions between temperature and aerial hypoxia on pulmonary ventilation and blood gases in L. paradoxa, and as described for other tetrapods Jackson, 1973;Kruhoffer et al, 1987;Munns et al, 1998), the hypoxic ventilatory response was amplified at high temperature. Currently, there are few data available on lungfish ventilation and breathing pattern during hypoxia, and data on gas exchange during hypoxia at high temperatures are lacking completely.…”

Section: Introductionmentioning

confidence: 94%

Effects of aerial hypoxia and temperature on pulmonary breathing pattern and gas exchange in the South American lungfish, Lepidosiren paradoxa

Silva

Ventura

Zena

et al. 2017

Comparative Biochemistry and Physiology Part A: Molecular &

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The South American lungfish Lepidosiren paradoxa is an obligatory air-breathing fish possessing well-developed bilateral lungs, and undergoing seasonal changes in its habitat, including temperature changes. In the present study we aimed to evaluate gas exchange and pulmonary breathing pattern in L. paradoxa at different temperatures (25 and 30°C) and different inspired O levels (21, 12, 10, and 7%). Normoxic breathing pattern consisted of isolated ventilatory cycles composed of an expiration followed by 2.4±0.2 buccal inspirations. Both expiratory and inspiratory tidal volumes reached a maximum of about 35mlkg, indicating that L. paradoxa is able to exchange nearly all of its lung air in a single ventilatory cycle. At both temperatures, hypoxia caused a significant increase in pulmonary ventilation (V̇), mainly due to an increase in respiratory frequency. Durations of the ventilatory cycle and expiratory and inspiratory tidal volumes were not significantly affected by hypoxia. Expiratory time (but not inspiratory) was significantly shorter at 30°C and at all O levels. While a small change in oxygen consumption (V̇O) could be noticed, the carbon dioxide release (V̇CO, P=0.0003) and air convection requirement (V̇/V̇O, P=0.0001) were significantly affected by hypoxia (7% O) at both temperatures, when compared to normoxia, and pulmonary diffusion capacity increased about four-fold due to hypoxic exposure. These data highlight important features of the respiratory system of L. paradoxa, capable of matching O demand and supply under different environmental change, as well as help to understand the evolution of air breathing in lungfish.

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“…It is conceivable that obligate sarcopterygians do not possess externally oriented O 2 chemoreceptors in the gills (Lahiri et al, 1970;Perry et al, 2005a;Silva et al, 2017). However, the actinopterygian and sarcopterygian species just cited, as well as the obligate air-breathing teleosts C. argus and Monopterus cuchia, show an increase in air-breathing frequency when exposed to aerial hypoxia, which may have been triggered by hypoxaemia through internally oriented chemoreceptors or by external chemoreceptors that monitor the P O2 of air in the ABO Lomholt and Johansen, 1974;Glass et al, 1986;Sanchez et al, 2001a;Zaccone et al, 2003Zaccone et al, , 2006Perry et al, 2005a;Silva et al, 2011Silva et al, , 2017. Nonetheless, the facultative sarcopterygian N. forsteri did not exhibit this response after the injection of nitrogen into the lung .…”

Section: Environmental Factorsmentioning

confidence: 99%

“…Regarding sarcopterygians, there is one report that external nicotine injections stimulate air-breathing in the African lungfish (P. aethiopicus) , but such kind of external stimuli has more often failed to trigger this behavior in dipnoans Sanchez et al, 2001a;Perry et al, 2005a). On the other hand, internal NaCN injections triggered air-breathing responses in P. aethiopicus (Lahiri et al, 1970), as well as exposure to aerial hypoxia did in L. paradoxa, P. aethiopicus and P. dolloi Sanchez et al, 2001a;Perry et al, 2005a;Silva et al, 2011Silva et al, , 2017. As pulmonary NECs were already found in lungfish (Zaccone et al, 1989(Zaccone et al, , 1997Kemp et al, 2003), it is possible that the exposure to aerial hypoxia stimulated air-breathing in these animals via external O 2 chemoreceptors in the lungs rather than internal O 2 chemoreceptorshowever, at least in the case of P. aethiopicus, such air-breathing response is eliminated by complete gill denervation (Lahiri et al, 1970).…”

Section: O 2 Chemoreceptorsmentioning

confidence: 99%

Control of air-breathing in fishes: Central and peripheral receptors

et al. 2018

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This review considers the environmental and systemic factors that can stimulate air-breathing responses in fishes with bimodal respiration, and how these may be controlled by peripheral and central chemoreceptors. The systemic factors that stimulate air-breathing in fishes are usually related to conditions that increase the O demand of these animals (e.g. physical exercise, digestion and increased temperature), while the environmental factors are usually related to conditions that impair their capacity to meet this demand (e.g. aquatic/aerial hypoxia, aquatic/aerial hypercarbia, reduced aquatic hidrogenionic potential and environmental pollution). It is now well-established that peripheral chemoreceptors, innervated by cranial nerves, drive increased air-breathing in response to environmental hypoxia and/or hypercarbia. These receptors are, in general, sensitive to O and/or CO/H levels in the blood and/or the environment. Increased air-breathing in response to elevated O demand may also be driven by the peripheral chemoreceptors that monitor O levels in the blood. Very little is known about central chemoreception in air-breathing fishes, the data suggest that central chemosensitivity to CO/H is more prominent in sarcopterygians than in actinopterygians. A great deal remains to be understood about control of air-breathing in fishes, in particular to what extent control systems may show commonalities (or not) among species or groups that have evolved air-breathing independently, and how information from the multiple peripheral (and possibly central) chemoreceptors is integrated to control the balance of aerial and aquatic respiration in these animals.

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Combined ventilatory responses to aerial hypoxia and temperature in the South American lungfish Lepidosiren paradoxa

Cited by 9 publications

References 28 publications

Ventilation and gas exchange in two turtles: Podocnemis unifilis and Phrynops geoffroanus (Testudines: Pleurodira)

Ventilation and gas exchange in two turtles: Podocnemis unifilis and Phrynops geoffroanus (Testudines: Pleurodira)

Effects of aerial hypoxia and temperature on pulmonary breathing pattern and gas exchange in the South American lungfish, Lepidosiren paradoxa

Control of air-breathing in fishes: Central and peripheral receptors

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