Pulmonary Blood Flow at Rest and during Swimming in the Green Turtle, Chelonia mydas

West, Nigel H.; Butler, Patrick J.; Bevan, R. M.

doi:10.1086/physzool.65.2.30158254

Cited by 57 publications

(52 citation statements)

References 18 publications

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“…2C,D). The capacity to differentially adjust V S,sys and V S,pul has been previously reported in turtles, with exercise inducing a greater increase in V S,pul than in V S,sys (West et al, 1992;Krosniunas and Hicks, 2003). The opposite was the case for H10 snapping turtles during the postprandial period (Fig.…”

Section: Postprandial Measurementssupporting

confidence: 56%

“…In 5-year-old snapping turtles, fasted and postprandial _ Q pul values (∼21-31 ml min −1 kg −1 ; Fig. 4A) were within the range for other turtle species at similar temperatures (∼15-56 ml kg −1 min −1 ; West et al, 1992;Wang and Hicks, 1996a;Hicks and Wang, 1998;Galli et al, 2004). However, _ Q sys of fasted N21 snapping turtles (6.54±0.90 ml kg −1 min −1 ; Fig.…”

Section: Fasted Measurementsmentioning

confidence: 51%

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Embryonic hypoxia programmes postprandial cardiovascular function in adult common snapping turtles (Chelydra serpentina)

Wearing

Conner

Nelson

et al. 2017

Journal of Experimental Biology

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Reduced oxygen availability (hypoxia) is a potent stressor during embryonic development, altering the trajectory of trait maturation and organismal phenotype. We previously documented that chronic embryonic hypoxia has a lasting impact on the metabolic response to feeding in juvenile snapping turtles (Chelydra serpentina). Turtles exposed to hypoxia as embryos [10% O 2 (H10)] exhibited an earlier and increased peak postprandial oxygen consumption rate, compared with control turtles [21% O 2 (N21)]. In the current study, we measured central blood flow patterns to determine whether the elevated postprandial metabolic response in H10 turtles is linked to lasting impacts on convective transport. Five years after hatching, turtles were instrumented to quantify systemic ( _ Q sys ) and pulmonary ( _ Q pul ) blood flows and heart rate ( f H ) before and after a ∼5% body mass meal. In adult N21 and H10 turtles, f H was increased significantly by feeding. Although total stroke volume (V S,tot ) remained at fasted values, this tachycardia contributed to an elevation in total cardiac output ( _ Q tot ). However, there was a postprandial reduction in a net left-right (L-R) shunt in N21 snapping turtles only. Relative to N21 turtles, H10 animals exhibited higher _ Q sys due to increased blood flow through the right systemic outflow vessels of the heart. This effect of hypoxic embryonic development, reducing a net L-R cardiac shunt, may support the increased postprandial metabolic rate we previously reported in H10 turtles, and is further demonstration of adult reptile cardiovascular physiology being programmed by embryonic hypoxia.

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Section: Postprandial Measurementssupporting

confidence: 56%

Section: Fasted Measurementsmentioning

confidence: 51%

Embryonic hypoxia programmes postprandial cardiovascular function in adult common snapping turtles (Chelydra serpentina)

Wearing

Conner

Nelson

et al. 2017

Journal of Experimental Biology

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“…1998, comparisons of the cardiovascular responses to these states can reveal the response that is associated with increased metabolism per se. While there still are relatively few studies that have measured the magnitude of cardiac shunts at different metabolic demands, all studies agree that the R-L shunt is reduced (or unchanged, but never increased) during activity, higher body temperature or during periods of digestion (West et al 1992, 1998reviewed by Wang & Hicks, 2001). Thus, while R-L shunts may have a functional role for resting animals with a low metabolic rate, they are able to decrease in magnitude when a high and efficient oxygen delivery is needed.…”

Section: Why Do Reptiles Have Cardiac Shunts?mentioning

confidence: 96%

“…In turtles, heart rate vH) and pulmonary blood flow (QP,,,) often increase immediately before breathing starts, which is suggestive of central mechanisms being important for the generation of these cdrdiovascular responses (e.g. West et al 1992;. It remains to be investigated whether separate pools of vagal motoneurones innervate the heart and the pulmonary artery.…”

Section: Vagal Control Of Tidal Volume and Breathing Patternmentioning

confidence: 99%

Physiological Society Symposium — Vagal Control: From Axolotl to Man

Wang

Warburton

Abe

et al. 2001

Experimental Physiology

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“…Neither can be considered as representing maximal rates of activity, as many reptiles attain higher rates of oxygen uptake and heart rate during digestion of very large meals than during physical activity (Bennett and Hicks, 2001;Wang et al, 2001b;Hicks and Bennett, 2004). That is the case of the rattlesnake, because the oxygen uptake at the peak of the SDA was more than twice the rate measured as V O2act in each group.The R-L shunt is normally reduced when metabolic rate increases in reptiles and amphibians (Hedrick et al, 1999;Hicks and Wang, 2012;Wang et al, 2001a;West et al, 1992) due to lowered vagal tone on the pulmonary artery as well as on the heart, accounting for part of the large rise in heart rate. Thus the LV snakes probably retained a normal cardiovascular response to increased metabolism.…”

mentioning

confidence: 99%

Ablation of the ability to control the right-to-left cardiac shunt does not affect oxygen consumption, specific dynamic action or growth in rattlesnakes,Crotalus durissus

Leite

Taylor

Wang

et al. 2013

Journal of Experimental Biology

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SUMMARYThe morphologically undivided ventricle of the heart in non-crocodilian reptiles permits the mixing of oxygen-rich blood returning from the lungs and oxygen-poor blood from the systemic circulation. A possible functional significance for this intra-cardiac shunt has been debated for almost a century. Unilateral left vagotomy rendered the single effective pulmonary artery of the South American rattlesnake, Crotalus durissus, unable to adjust the magnitude of blood flow to the lung. The higher constant perfusion of the lung circulation and the incapability of adjusting the right-left shunt in left-denervated snakes persisted over time, providing a unique model for investigation of the long-term consequences of cardiac shunting in a squamate. Oxygen uptake recorded at rest and during spontaneous and forced activity was not affected by removing control of the cardiac shunt. Furthermore, metabolic rate and energetic balance during the post-prandial metabolic increment, plus the food conversion efficiency and growth rate, were all similarly unaffected. These results show that control of cardiac shunting is not associated with a clear functional advantage in adjusting metabolic rate, effectiveness of digestion or growth rates.Key words: cardiac shunt, vagotomy, rattlesnake, Crotalus, oxygen uptake, heart. THE JOURNAL OF EXPERIMENTAL BIOLOGY 1882 model to study the consequences of long-term manipulation of their ability to induce R-L cardiac shunts, we investigated the survivorship consequences of shunt ablation. This was achieved by measuring growth and food intake plus rates of oxygen uptake during rest, during spontaneous activity, following enforced activity and after ingestion of food in snakes vagotomised on the left or right side and in a control group subjected to a sham denervation. It has been argued that appetite, food conversion and long-term growth rate can provide more robust measures of fitness than measurement of physiological variables (Chamaille-Jammes et al., 2006;Eme et al., 2010;Sinervo and Adolph, 1989). MATERIALS AND METHODS Experimental animalsSouth American rattlesnakes [Crotalus durissus terrificus (Laurenti 1768)] used to study growth, food assimilation and metabolic rate, including specific dynamic action and activity, were born in captivity at the State University of São Paulo (UNESP) (Rio Claro, São Paulo State, Brazil). They were 1month old, with a mean mass of 30±4g (N=21) when the study commenced. An additional 16 adult snakes (1598±682g), acquired from the Butantan Institute (Sao Paulo) were used to determine oxygen uptake during rest and activity. The snakes were maintained individually in plastic boxes (40×29×27cm) at 28-30°C with ad libitum access to water. The snakes were fed to satiety on mice once a week, while the adult snakes were given rats to satiety every third week. Satiety was assumed when each snake stopped striking/ingesting the next in succession of the mice/rats offered. All experiments were approved by the ethical committee on animal experimentation (Comissã...

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Pulmonary Blood Flow at Rest and during Swimming in the Green Turtle, Chelonia mydas

Cited by 57 publications

References 18 publications

Embryonic hypoxia programmes postprandial cardiovascular function in adult common snapping turtles (Chelydra serpentina)

Embryonic hypoxia programmes postprandial cardiovascular function in adult common snapping turtles (Chelydra serpentina)

Physiological Society Symposium — Vagal Control: From Axolotl to Man

Ablation of the ability to control the right-to-left cardiac shunt does not affect oxygen consumption, specific dynamic action or growth in rattlesnakes,Crotalus durissus

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