Functional role of cardiac shunts in reptiles

Hicks, James W.; Wang, Tobias

doi:10.1002/(sici)1097-010x(19960601/15)275:2/3<204::aid-jez12>3.0.co;2-j

Cited by 60 publications

(31 citation statements)

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“…In sea turtles, it has been hypothesized that the muscular sphincters within the pulmonary arteries contract during diving, shunting blood away from the lungs 16, 20 . This response may prevent N 2 uptake during the dive, thus minimizing the risk of DCS.…”

Section: Discussionmentioning

confidence: 99%

Defining risk variables causing gas embolism in loggerhead sea turtles (Caretta caretta) caught in trawls and gillnets

Fahlman

Crespo-Picazo

Sterba-Boatwright

et al. 2017

Sci Rep

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Incidental capture, or ‘bycatch’ in fishing gear is a major global threat to sea turtle populations. A recent study showed that underwater entrapment in fishing gear followed by rapid decompression may cause gas bubble formation within the blood stream (embolism) and tissues leading to organ injury, impairment, and even mortality in some bycaught individuals. We analyzed data from 128 capture events using logistic and ordinal regression to examine risk factors associated with gas embolism in sea turtles captured in trawls and gillnets. Likelihood of fatal decompression increases with increasing depth of gear deployment. A direct relationship was found between depth, risk and severity of embolism, which has not been previously demonstrated in any breath-hold diving species. For the trawl fishery in this study, an average trawl depth of 65 m was estimated to result in 50% mortality in by-caught turtles throughout the year. This finding is critical for a more accurate estimation of sea turtle mortality rates resulting from different fisheries and for devising efforts to avoid or minimize the harmful effects of capture.

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Section: Discussionmentioning

confidence: 99%

Defining risk variables causing gas embolism in loggerhead sea turtles (Caretta caretta) caught in trawls and gillnets

Fahlman

Crespo-Picazo

Sterba-Boatwright

et al. 2017

Sci Rep

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“… Schematic drawing of the adult testudine heart, shown in ventral view (drawing based on Hicks and Wang,1996). For the meaning of abbreviations, see list of abbreviations.…”

Section: Current Knowledge Of the Adult Turtle Heartmentioning

confidence: 99%

“…The horizontal septum (in the horizontal plane, from left to right sides of the ventricle) is complete on the caudal end of the ventricle, but incomplete on the cranial end. It is sometimes called “Muskelleiste” in German, or “muscular ridge” in English (Webb et al,1971; Van Mierop and Kutsche,1984; Van Mierop and Kutsche,1985; Burggren,1988; Hicks and Wang,1996). However, like Holmes (Holmes,1976) we consider these terms rather confusing, since “Muskelleiste” can be translated as “muscular ridge”, which in turn is a term used for both vertical septum and in general for all trabeculae carneae.…”

Section: Current Knowledge Of the Adult Turtle Heartmentioning

confidence: 99%

“…During atrial systole the intraventricular canal is closed by the atrio‐ventricular valves, which are forced caudally, into the ventricle, by the pressure of the blood flowing from atria into the ventricle. In this way all the blood from the left atrium is pumped into the cavum arteriosum (White,1968; Johansen and Burggren,1980; Hicks and Wang,1996). This process is illustrated in Fig.…”

Section: Current Knowledge Of the Adult Turtle Heartmentioning

confidence: 99%

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Analysis of Cardiac Development in the TurtleEmys orbicularis(Testudines: Emidydae) using 3‐D Computer Modeling from Histological Sections

Bertens

Richardson

Verbeek

2010

The Anatomical Record

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In this article we present a 3-D modeling study of cardiac development in the European pond turtle, Emys orbicularis (of the reptilian order Testudines). The study is aimed at elucidating the embryonic development of the horizontal septum in the ventricle and underscoring the importance of 3-D reconstructions in studying morphogenesis. Turtles possess one common ventricle, partly divided into three cava by a vertical and a horizontal septum, of which the embryonic origins have so far not been described. We used serial sectioning and computerized high-resolution 3-D reconstructions of different developmental stages to create a chronological overview of cardiogenesis, in order to study this process. This has yielded a new understanding of the development of the horizontal septum and (directly related) the looping of the heart tube. This looping is found to be markedly different from that in the human heart, with the turtle having two clear bends in the part of the heart tube leaving the primitive ventricle, as opposed to one in humans. It is this particular looping that is reponsible for the formation of the horizontal septum. In addition to our findings on the ventricular septation this study has also yielded new insights into the developmental origins of the pulmonary vein. The 3-D reconstructions were built using our platform TDR-3-D base and enabled us to study the developmental processes in specific parts of the turtle heart separately and in three dimensions, over time. The complete 3-D reconstructions have been made available to the reader via internet using our 3-D model browser application, which allows interactive viewing of the models. The browser application can be found on bio-imaging.liacs.nl/galleries/emysorbicularis/TurtleGallery.html, along with additional images of both models and histological sections and animation sequences of the models. By allowing the reader to view the mate-

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“…This unique circulatory arrangement has been hypothesized to be of adaptive significance for crocodilians in a number of ecological and physiological scenarios, such as extending aerobic dive times (Grigg and Johansen 1987) and facilitating digestion by carrying CO 2 to the stomach to aid gastric acid secretion (Jones and Shelton 1993; Farmer et al 2008). However, these hypothesized physiological functions of R–L cardiac shunt may not be experimentally supported in crocodilians and other reptiles (Hicks and Wang 1996). For example, recent studies have demonstrated that surgical reduction or elimination of R–L cardiac shunt did not alter in a freely diving turtle ( Trachemys scripta ; Wang and Hicks 2008) or American alligator ( Alligator mississippiensis ; Eme et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Role of the left aortic arch and blood flows in embryonic American alligator (Alligator mississippiensis)

2010

Self Cite

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All embryonic and fetal amniotes possess a ductus(i) arteriosus(i) that allows blood to bypass the pulmonary circulation and the non-functional lungs. The central hemodynamic of embryonic reptiles are unique, given the additional systemic aorta that allows pulmonary circulatory bypass, the left aorta (LAo). The LAo exits in the right ventricle or ‘pulmonary side’ of reptilian hearts in both embryos and adults, but its functional significance in ovo is unknown. This study investigated the role of the LAo in embryonic American alligators by surgically occluding the LAo and measuring oxygen consumption and, in addition, measured hemodynamic responses to hypoxia in embryonic alligators. We measured systemic cardiac output and primary chorioallantoic membrane (CAM) artery blood flow for normoxic and hypoxic-incubated (10% O2) American alligator embryos (Alligator mississippiensis). Chronic blood flow (1–124 h) in the primary CAM artery for hypoxic-incubated embryos (92 ± 26 ml min−1 kg−1) was elevated when compared with normoxic-incubated embryos (29 ± 14 ml min−1 kg−1, N = 6; P = 0.039). For hypoxic-incubated embryos, acute LAo blood flow (49.6 ± 24.4 ml min−1 kg−1) was equivalent to the combined flow of the three systemic great vessels that arise from the left ventricle, the right aorta, common carotid and subclavian arteries (43.6 ± 21.5 ml min−1 kg−1, N = 5). Similarly, for normoxic-incubated embryos, LAo blood flow (27.3 ± 6.6 ml min−1 kg−1) did not statistically differ from the other three vessels (18.4 ± 4.9 ml min−1 kg−1, N = 5). This study contains the first direct test of LAo function and the first measurements of blood flow in an embryonic reptile. These data support the hypotheses that embryonic alligators utilize the LAo to divert a significant amount of right ventricular blood into the systemic circulation, and that CAM blood flow increases following chronic hypoxic conditions. However, surgical occlusion of the LAo did not affect egg supporting the hypothesis that the LAo of reptiles is not critical to maintain in ovo oxygen consumption.Electronic supplementary materialThe online version of this article (doi:10.1007/s00360-010-0494-6) contains supplementary material, which is available to authorized users.

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Functional role of cardiac shunts in reptiles

Cited by 60 publications

References 50 publications

Defining risk variables causing gas embolism in loggerhead sea turtles (Caretta caretta) caught in trawls and gillnets

Defining risk variables causing gas embolism in loggerhead sea turtles (Caretta caretta) caught in trawls and gillnets

Analysis of Cardiac Development in the TurtleEmys orbicularis(Testudines: Emidydae) using 3‐D Computer Modeling from Histological Sections

Role of the left aortic arch and blood flows in embryonic American alligator (Alligator mississippiensis)

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