Breathing pattern and cost of ventilation in the american alligator

Wang, Tobias; Warburton, Stephen J.

doi:10.1016/0034-5687(95)00043-d

Cited by 45 publications

(31 citation statements)

References 18 publications

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“…1A) for measurements of gas exchange and ventilation was similar to previous descriptions (Wang and Warburton, 1995). One end of the T-piece of the facemask was connected to a side-tube connected to a mass flow meter (Sierra Instruments, Inc.), whilst the other was connected to CO 2 and O 2 analysers (AEI Technologies) and a steady flow was pulled through the side tube using two parallel arranged flow controllers (R2 Flow Control from AEI Technologies and the other custom-made).…”

Section: Measurements Of Gas Exchange and Ventilationsupporting

confidence: 81%

“…even a decrease in VĖ (de Andrade et al, 2004;Milsom et al, 2004;Nielsen, 1961;Tattersall et al, 2006;Wang and Warburton, 1995). We also observed rather variable ventilatory responses among individuals at 4% CO 2 , and the small ventilatory response may have contributed to a slow course of gas exchange, so steady state was not reached within 90 min at 4% CO 2 as indicated by RER remaining considerable lower than the possible RQ range.…”

Section: Discussionmentioning

confidence: 68%

“…Given the constant flow pulled downstream from the mask and into the O 2 and CO 2 sensors, gas exchange per breath could be calculated as the product of the integrated gas fraction below or above baseline and the flow rate. This was verified as previously described (Wang and Warburton, 1995) by simulating exhalations with known gas compositions via injecting known volumes of O 2 and CO 2 into the circuit with the mask glued to a cast, thereby establishing tight (R 2 =0.999) proportional relations between the calculated volumes and the injected volumes (slope of 0.96). All data was collected using BioPac data acquisition systems.…”

Section: Measurements Of Gas Exchange and Ventilationmentioning

confidence: 58%

“…During measurements they were placed in a dark box in a heating cabinet at 23 or 33°C to minimize disturbance. Animals were fitted with a face-mask glued to the head with fast hardening epoxy glue as previously described by Glass et al (1978) and Wang and Warburton (1995). Animals were placed at test temperature at least 16-20 h before measurements in order for the bodily CO 2 stores to adjust to the new body temperature (e.g.…”

Section: Materials and Methods Animals And Instrumentationmentioning

confidence: 99%

“…Here, we determine time constants for changes in gas exchange (and thus, indirectly, bodily gas stores) and ventilatory responses to hypoxia and hypercapnia in Cuvier's dwarf caimans (Paleosuchus palpebrosus), a suitable species for simultaneous measurements of gas exchange and ventilation using pneumotachography (Glass et al, 1978;Wang and Warburton, 1995). Given the present difficulty in acquiring precise blood gas values at a high sampling rate (Malte et al, 2014), we used changes in RER (CO 2 excretion divided by O 2 uptake) as a proxy for changes in bodily gas stores because RER ideally will approach a steady state equal to the respiratory quotient [RQ; tissue CO 2 production divided by O 2 consumption (Farhi and Rahn, 1955)].…”

Section: Introductionmentioning

confidence: 99%

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The long road to steady state in gas exchange: metabolic and ventilatory responses to hypercapnia and hypoxia in Cuvier’s dwarf caiman

Malte

Wang

2016

Journal of Experimental Biology

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Animals with intermittent lung ventilation and those exposed to hypoxia and hypercapnia will experience fluctuations in the bodily O 2 and CO 2 stores, but the magnitude and duration of these changes are not well understood amongst ectotherms. Using the changes in the respiratory exchange ratio (RER; CO 2 excretion divided by O 2 uptake) as a proxy for changes in bodily gas stores, we quantified time constants in response to hypoxia and hypercapnia in Cuvier's dwarf caiman. We confirm distinct and prolonged changes in RER during and after exposure to hypoxia or hypercapnia. Gas exchange transients were evaluated in reference to predictions from a twocompartment model of CO 2 exchange to quantify the effects of the levels of hypoxia and hypercapnia, duration of hypercapnia (30-300 min) and body temperature (23 versus 33°C). For hypercapnia, the transients could be adequately fitted by two-phase exponential functions, and slow time constants (after 300 min hypercapnia) concurred reasonably well with modelling predictions. The slow time constants for the decays after hypercapnia were not affected by the level of hypercapnia, but they increased (especially at 23°C) with exposure time, possibly indicating a temporal and slow recruitment of tissues for CO 2 storage. In contrast to modelling predictions, elevated body temperature did not reduce the time constants, probably reflecting similar ventilation rates in transients at 23 and 33°C. Our study reveals that attainment of steady state for gas exchange requires considerable time and this has important implications for designing experimental protocols when studying ventilatory control and conducting respirometry.

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Section: Measurements Of Gas Exchange and Ventilationsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 68%

Section: Measurements Of Gas Exchange and Ventilationmentioning

confidence: 58%

Section: Materials and Methods Animals And Instrumentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The long road to steady state in gas exchange: metabolic and ventilatory responses to hypercapnia and hypoxia in Cuvier’s dwarf caiman

Malte

Wang

2016

Journal of Experimental Biology

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Control of Breathing in Ectothermic Vertebrates

Milsom

Gilmour

Perry

et al. 2022

Comprehensive Physiology

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The ectothermic vertebrates are a diverse group that includes the Fishes (Agnatha, Chondrichthyes, and Osteichthyes), and the stem Tetrapods (Amphibians and Reptiles). From an evolutionary perspective, it is within this group that we see the origin of air-breathing and the transition from the use of water to air as a respiratory medium. This is accompanied by a switch from gills to lungs as the major respiratory organ and from oxygen to carbon dioxide as the primary respiratory stimulant. This transition first required the evolution of bimodal breathing (gas exchange with both water and air), the differential regulation of O 2 and CO 2 at multiple sites, periodic or intermittent ventilation, and unsteady states with wide oscillations in arterial blood gases. It also required changes in respiratory pump muscles (from buccopharyngeal muscles innervated by cranial nerves to axial muscles innervated by spinal nerves). The question of the extent to which common mechanisms of respiratory control accompany this progression is an intriguing one. While the ventilatory control systems seen in all extant vertebrates have been derived from common ancestors, the trends seen in respiratory control in the living members of each vertebrate class reflect both shared-derived features (ancestral traits) as well as unique specializations. In this overview article, we provide a comprehensive survey of the diversity that is seen in the afferent inputs (chemo and mechanoreceptor), the central respiratory rhythm generators, and the efferent outputs (drive to the respiratory pumps and valves) in this group.

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A cineradiographic study of lung ventilation in Alligator mississippiensis

Claessens

2009

J. Exp. Zool.

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The skeletal and visceral kinematics of lung ventilation of the American alligator (Alligator mississippiensis) was examined using cineradiography, pneumotachometry, and intrapulmonary pressure recording. The respiratory pattern of A. mississippiensis is intermittent and diphasic. The inspiratory lung volume is retained during the non-ventilatory period through closure of the glottis. The aspiration pump of A. mississippiensis consists of multiple components: visceral movement, pubic rotation, gastralial movement, and costosternal movement, which vary independently in their contribution to lung ventilation. Vertebral flexion and extension is also observed, and may be a passive artifact of costal displacement. The amount of craniocaudal visceral movement during lung ventilation is variable, and can produce as much as 60% of the tidal volume. Pubic rotation is not directly coupled to visceral movement and contributes a relatively small percentage of the tidal volume, approximately 4% on average, as does vertebral flexion, which contributes less than 3%. Costosternal movement contributes the remaining majority of tidal volume, generally over 40%. The gastralia stiffen the abdominal wall and likely facilitate unified displacement of the abdominal wall. Tripartite ribs facilitate thoracic movement, allowing substantial excursion of the body wall. A relatively abrupt change in position of the vertebral parapophysis in the anterior thorax results in an increase in lateral rib movement in the posterior half of the thorax. The crocodylian aspiration pump appears to consist of a derived pelvic and diaphragmatic breathing pump combined with a basal costosternal and gastralial aspiration pump.

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Breathing pattern and cost of ventilation in the american alligator

Cited by 45 publications

References 18 publications

The long road to steady state in gas exchange: metabolic and ventilatory responses to hypercapnia and hypoxia in Cuvier’s dwarf caiman

The long road to steady state in gas exchange: metabolic and ventilatory responses to hypercapnia and hypoxia in Cuvier’s dwarf caiman

Control of Breathing in Ectothermic Vertebrates

A cineradiographic study of lung ventilation in Alligator mississippiensis

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