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Poulsen CFB, Munk K, Wang T, Damkjaer M. Transesophageal echocardiography of cardiac function in Nile crocodiles - A novel tool for assessing complex hemodynamic patterns. Comp Biochem Physiol A Mol Integr Physiol 2024; 288:111564. [PMID: 38135145 DOI: 10.1016/j.cbpa.2023.111564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 12/12/2023] [Accepted: 12/18/2023] [Indexed: 12/24/2023]
Abstract
BACKGROUND The crocodilian heart is unique among reptiles with its four-chambered structure and complete intracardiac separation of pulmonary and systemic blood flows and pressures. Crocodiles have retained two aortic arches; one from each ventricle, that communicate via Foramen of Panizza, immediately distally from the aortic valves. Moreover, crocodiles can regulate vascular resistance in the pulmonary portion of the right ventricular outflow tract (RVOT). These unique features allow for a complex regulation of shunting between the pulmonary and systemic circulations. Studies on crocodile shunting have predominantly been based on invasive measurements, but here we report on the use of echocardiography. METHODS Experiments were performed on seven pentobarbital anaesthetized juvenile Nile crocodiles (length and mass of 192 ± 13 cm and 26 ± 5 kg, respectively). Echocardiographic imaging was performed using a transesophageal (TEE) approach. All images were EKG-gated. RESULTS We obtain excellent views of cardiac structures and central vasculature through the esophagus. Standard imaging planes were defined for both long- and short axis views of the left ventricle and truncus arteriosus. For the RV, only a short axis view could be obtained. Color Doppler was used to visualize flow. Pulsed waved Doppler for measuring flow profiles across the atrioventricular valves, in the two RVOTs and the left ventricular outflow tract. Shunting across the Foramen of Panizza could be visualized and gated to the EKG. CONCLUSION TEE can be used to image the unique features of the crocodile heart and allow for in-vivo imaging of the complex shunting hemodynamics, including timing of cardiac shunts.
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Affiliation(s)
- Christian F B Poulsen
- Department of Cardiology, Aalborg University Hospital, Denmark; Department of Paediatrics and Adolescent Medicine, Lillebaelt Hospital, University Hospital of Southern Denmark, Kolding, Denmark; Department of Regional Health Research, University of Southern Denmark, Denmark
| | - Kim Munk
- Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark
| | - Tobias Wang
- Department of Zoophysiology, Aarhus University, Aarhus, Denmark. https://twitter.com/Tobias_Wang_AU
| | - Mads Damkjaer
- Department of Paediatrics and Adolescent Medicine, Lillebaelt Hospital, University Hospital of Southern Denmark, Kolding, Denmark; Department of Regional Health Research, University of Southern Denmark, Denmark.
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Gregorovicova M, Lashkarinia SS, Yap CH, Tomek V, Sedmera D. Hemodynamics During Development and Postnatal Life. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1441:201-226. [PMID: 38884713 DOI: 10.1007/978-3-031-44087-8_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
A well-developed heart is essential for embryonic survival. There are constant interactions between cardiac tissue motion and blood flow, which determine the heart shape itself. Hemodynamic forces are a powerful stimulus for cardiac growth and differentiation. Therefore, it is particularly interesting to investigate how the blood flows through the heart and how hemodynamics is linked to a particular species and its development, including human. The appropriate patterns and magnitude of hemodynamic stresses are necessary for the proper formation of cardiac structures, and hemodynamic perturbations have been found to cause malformations via identifiable mechanobiological molecular pathways. There are significant differences in cardiac hemodynamics among vertebrate species, which go hand in hand with the presence of specific anatomical structures. However, strong similarities during development suggest a common pattern for cardiac hemodynamics in human adults. In the human fetal heart, hemodynamic abnormalities during gestation are known to progress to congenital heart malformations by birth. In this chapter, we discuss the current state of the knowledge of the prenatal cardiac hemodynamics, as discovered through small and large animal models, as well as from clinical investigations, with parallels gathered from the poikilotherm vertebrates that emulate some hemodynamically significant human congenital heart diseases.
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Affiliation(s)
- Martina Gregorovicova
- Laboratory of Developmental Cardiology, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | | | - Choon Hwai Yap
- Department of Bioengineering, Imperial College, London, UK
| | - Viktor Tomek
- Pediatric Cardiology, Motol University Hospital, Prague, Czech Republic
| | - David Sedmera
- Laboratory of Developmental Cardiology, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague, Czech Republic.
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Gregorovicova M, Bartos M, Jensen B, Janacek J, Minne B, Moravec J, Sedmera D. Anguimorpha as a model group for studying the comparative heart morphology among Lepidosauria: Evolutionary window on the ventricular septation. Ecol Evol 2022; 12:e9476. [PMID: 36381397 PMCID: PMC9643144 DOI: 10.1002/ece3.9476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 10/10/2022] [Accepted: 10/14/2022] [Indexed: 11/11/2022] Open
Abstract
The group Anguimorpha represents one of the most unified squamate clades in terms of body plan, ecomorphology, ecophysiology and evolution. On the other hand, the anguimorphs vary between different habitats and ecological niches. Therefore, we focused on the group Anguimorpha to test a possible correlation between heart morphology and ecological niche with respect to phylogenetic position in Squamata with Sphenodon, Salvator, and Pogona as the outgroups. The chosen lepidosaurian species were investigated by microCT. Generally, all lepidosaurs had two well‐developed atria with complete interatrial septum and one ventricle divided by ventricular septa to three different areas. The ventricles of all lepidosaurians had a compact layer and abundant trabeculae. The compact layer and trabeculae were developed in accordance with particular ecological niche of the species, the trabeculae in nocturnal animals with low metabolism, such as Sphenodon, Heloderma or Lanthanotus were more massive. On the other hand athletic animals, such as varanids or Salvator, had ventricle compartmentalization divided by three incomplete septa. A difference between varanids and Salvator was found in compact layer thickness: thicker in monitor lizards and possibly linked to their mammalian‐like high blood pressure, and the level of ventricular septation. In summary: heart morphology varied among clades in connection with the ecological niche of particular species and it reflects the phylogenetic position in model clade Anguimorpha. In the absence of fossil evidence, this is the closest approach how to understand heart evolution and septation in clade with different cardiac compartmentalization levels.
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Affiliation(s)
- Martina Gregorovicova
- First Faculty of Medicine, Institute of Anatomy Charles University Prague Czech Republic
| | - Martin Bartos
- First Faculty of Medicine, Institute of Anatomy Charles University Prague Czech Republic
- First Faculty of Medicine Institute of Dental Medicine, Charles University Prague Czech Republic
| | - Bjarke Jensen
- Department of Medical Biology, Amsterdam Cardiovascular Sciences University of Amsterdam Amsterdam The Netherlands
| | - Jiri Janacek
- Laboratory of Biomathematics, Institute of Physiology Czech Academy of Sciences Prague Czech Republic
| | - Bryan Minne
- Amphibian Evolution Lab Free University of Brussels Brussels Belgium
| | | | - David Sedmera
- First Faculty of Medicine, Institute of Anatomy Charles University Prague Czech Republic
- Laboratory of Developmental Cardiology, Institute of Physiology Czech Academy of Sciences Prague Czech Republic
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Young BA, Cramberg MJ. Treadmill locomotion in the American alligator (Alligator mississippiensis) produces dynamic changes in intracranial cerebrospinal fluid pressure. Sci Rep 2022; 12:11826. [PMID: 35821242 PMCID: PMC9276781 DOI: 10.1038/s41598-022-15918-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 07/01/2022] [Indexed: 11/09/2022] Open
Abstract
To examine the influence of movement on cerebrospinal fluid (CSF) dynamics, intracranial subdural pressure recordings were taken from sub-adult alligators (Alligator mississippiensis) locomoting on a treadmill. Pressure recordings documenting the cardiac, ventilatory, and barostatic influences on the CSF were in good agreement with previous studies. During locomotion the CSF exhibits sinusoidal patterns of pressure change that spanned a mean amplitude of 56 mm Hg, some 16 × the amplitude of the cardiac-linked pulsations. These sinusoidal CSF pulsations were closely linked to the locomotor kinematics, particularly the lateral oscillations of the alligator's head. Data recorded from the freely moving alligators suggest that fluid inertia, body cavity pressures, and likely other factors all influence the CSF pressure. The clear relationship between movement and CSF pressure described in this study suggests that the paucity of studies examining human CSF dynamics during movement should be addressed.
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Affiliation(s)
- Bruce A Young
- Department of Anatomy, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA.
| | - Michael J Cramberg
- Department of Anatomy, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA
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Starck JM, Wyneken J. Comparative and Functional Anatomy of the Ectothermic Sauropsid Heart. Vet Clin North Am Exot Anim Pract 2022; 25:337-366. [PMID: 35422257 DOI: 10.1016/j.cvex.2022.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The heart development, form, and functional specializations of chelonians, squamates, crocodilians, and birds characterize how diverse structure and specializations arise from similar foundations. This review aims to summarize the morphologic diversity of sauropsid hearts and present it in an integrative functional and phylogenetic context. Besides the detailed morphologic descriptions, the integrative view of function, evolution, and development will aid understanding of the surprising diversity of sauropsid hearts. This integrated perspective is a foundation that strengthens appreciation that the sauropsid hearts are the outcome of biological evolution; disease often is linked to arising mismatch between adaptations and modern environments.
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Affiliation(s)
- J Matthias Starck
- Department of Biology, Ludwig-Maximilians-University Munich, Planegg-Martinsried D82152, Germany.
| | - Jeanette Wyneken
- Florida Atlantic University, FAU Marine Lab at Gumbo Limbo Environmental Complex, Boca Raton, FL 33431-0991, USA
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Grigg G, Nowack J, Bicudo JEPW, Bal NC, Woodward HN, Seymour RS. Whole-body endothermy: ancient, homologous and widespread among the ancestors of mammals, birds and crocodylians. Biol Rev Camb Philos Soc 2021; 97:766-801. [PMID: 34894040 PMCID: PMC9300183 DOI: 10.1111/brv.12822] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/25/2021] [Accepted: 11/29/2021] [Indexed: 12/31/2022]
Abstract
The whole‐body (tachymetabolic) endothermy seen in modern birds and mammals is long held to have evolved independently in each group, a reasonable assumption when it was believed that its earliest appearances in birds and mammals arose many millions of years apart. That assumption is consistent with current acceptance that the non‐shivering thermogenesis (NST) component of regulatory body heat originates differently in each group: from skeletal muscle in birds and from brown adipose tissue (BAT) in mammals. However, BAT is absent in monotremes, marsupials, and many eutherians, all whole‐body endotherms. Indeed, recent research implies that BAT‐driven NST originated more recently and that the biochemical processes driving muscle NST in birds, many modern mammals and the ancestors of both may be similar, deriving from controlled ‘slippage’ of Ca2+ from the sarcoplasmic reticulum Ca2+‐ATPase (SERCA) in skeletal muscle, similar to a process seen in some fishes. This similarity prompted our realisation that the capacity for whole‐body endothermy could even have pre‐dated the divergence of Amniota into Synapsida and Sauropsida, leading us to hypothesise the homology of whole‐body endothermy in birds and mammals, in contrast to the current assumption of their independent (convergent) evolution. To explore the extent of similarity between muscle NST in mammals and birds we undertook a detailed review of these processes and their control in each group. We found considerable but not complete similarity between them: in extant mammals the ‘slippage’ is controlled by the protein sarcolipin (SLN), in birds the SLN is slightly different structurally and its role in NST is not yet proved. However, considering the multi‐millions of years since the separation of synapsids and diapsids, we consider that the similarity between NST production in birds and mammals is consistent with their whole‐body endothermy being homologous. If so, we should expect to find evidence for it much earlier and more widespread among extinct amniotes than is currently recognised. Accordingly, we conducted an extensive survey of the palaeontological literature using established proxies. Fossil bone histology reveals evidence of sustained rapid growth rates indicating tachymetabolism. Large body size and erect stature indicate high systemic arterial blood pressures and four‐chambered hearts, characteristic of tachymetabolism. Large nutrient foramina in long bones are indicative of high bone perfusion for rapid somatic growth and for repair of microfractures caused by intense locomotion. Obligate bipedality appeared early and only in whole‐body endotherms. Isotopic profiles of fossil material indicate endothermic levels of body temperature. These proxies led us to compelling evidence for the widespread occurrence of whole‐body endothermy among numerous extinct synapsids and sauropsids, and very early in each clade's family tree. These results are consistent with and support our hypothesis that tachymetabolic endothermy is plesiomorphic in Amniota. A hypothetical structure for the heart of the earliest endothermic amniotes is proposed. We conclude that there is strong evidence for whole‐body endothermy being ancient and widespread among amniotes and that the similarity of biochemical processes driving muscle NST in extant birds and mammals strengthens the case for its plesiomorphy.
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Affiliation(s)
- Gordon Grigg
- School of Biological Sciences, University of Queensland, Brisbane, QLD, 4072, Australia
| | - Julia Nowack
- School of Biological and Environmental Sciences, Liverpool John Moores University, James Parsons Building, Byrom Street, Liverpool, L3 3AF, U.K
| | | | | | - Holly N Woodward
- Oklahoma State University Center for Health Sciences, Tulsa, OK, 74107, U.S.A
| | - Roger S Seymour
- School of Biological Sciences, University of Adelaide, Adelaide, SA, 5005, Australia
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Poelmann RE, Gittenberger-de Groot AC, Goerdajal C, Grewal N, De Bakker MAG, Richardson MK. Ventricular Septation and Outflow Tract Development in Crocodilians Result in Two Aortas with Bicuspid Semilunar Valves. J Cardiovasc Dev Dis 2021; 8:jcdd8100132. [PMID: 34677201 PMCID: PMC8537894 DOI: 10.3390/jcdd8100132] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/14/2021] [Accepted: 09/27/2021] [Indexed: 02/07/2023] Open
Abstract
Background: The outflow tract of crocodilians resembles that of birds and mammals as ventricular septation is complete. The arterial anatomy, however, presents with a pulmonary trunk originating from the right ventricular cavum, and two aortas originating from either the right or left ventricular cavity. Mixing of blood in crocodilians cannot occur at the ventricular level as in other reptiles but instead takes place at the aortic root level by a shunt, the foramen of Panizza, the opening of which is guarded by two facing semilunar leaflets of both bicuspid aortic valves. Methods: Developmental stages of Alligator mississipiensis, Crocodilus niloticus and Caiman latirostris were studied histologically. Results and Conclusions: The outflow tract septation complex can be divided into two components. The aorto-pulmonary septum divides the pulmonary trunk from both aortas, whereas the interaortic septum divides the systemic from the visceral aorta. Neural crest cells are most likely involved in the formation of both components. Remodeling of the endocardial cushions and both septa results in the formation of bicuspid valves in all three arterial trunks. The foramen of Panizza originates intracardially as a channel in the septal endocardial cushion.
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Affiliation(s)
- Robert E. Poelmann
- Sylvius Laboratory, Department of Animal Sciences and Health, Institute of Biology, University of Leiden, Sylvi-usweg 72, 2333BE Leiden, The Netherlands; (C.G.); (M.A.G.D.B.); (M.K.R.)
- Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, P.O. Box 9600, 2300RC Leiden, The Netherlands;
- Correspondence: ; Tel.: +31-652695875
| | | | - Charissa Goerdajal
- Sylvius Laboratory, Department of Animal Sciences and Health, Institute of Biology, University of Leiden, Sylvi-usweg 72, 2333BE Leiden, The Netherlands; (C.G.); (M.A.G.D.B.); (M.K.R.)
| | - Nimrat Grewal
- Department of Cardiothoracic Surgery, Leiden University Medical Center, Albinusdreef 2, P.O. Box 9600, 2300RC Leiden, The Netherlands;
| | - Merijn A. G. De Bakker
- Sylvius Laboratory, Department of Animal Sciences and Health, Institute of Biology, University of Leiden, Sylvi-usweg 72, 2333BE Leiden, The Netherlands; (C.G.); (M.A.G.D.B.); (M.K.R.)
| | - Michael K. Richardson
- Sylvius Laboratory, Department of Animal Sciences and Health, Institute of Biology, University of Leiden, Sylvi-usweg 72, 2333BE Leiden, The Netherlands; (C.G.); (M.A.G.D.B.); (M.K.R.)
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Mitova E, Wittnich C. Cardiac Structures in Marine Animals Provide Insight on Potential Directions for Interventions for Pediatric Congenital Heart Defects. Am J Physiol Heart Circ Physiol 2021; 322:H1-H7. [PMID: 34652986 DOI: 10.1152/ajpheart.00451.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite recent advances in pediatric diagnosis and surgical intervention, mortality and morbidity continue to be a prevalent issue in both Tetralogy of Fallot (ToF) and Hypoplastic Left Heart Syndrome (HLHS). Therefore, novel approaches to studying both of these conditions is warranted. Investigating cardiac anatomical features of different species in the animal kingdom similar to the defects and complications present in ToF and HLHS (as well as others) could serve as a new avenue for improving the management of congenital heart diseases (CHD). This review reveals that although structures found in HLHS and ToF are pathological, similar structures are found in diving mammals and reptiles that are adaptive. Pathologic aortic dilation in CHD resembles the aortic bulb present in diving mammals, but the latter is more elastic and distensible compared to the former. The unrepaired HLHS heart resembles the univentricular heart of non-crocodilian reptiles. Right ventricle hypertrophy is pathological in HLHS and ToF, but adaptive in crocodilians and diving mammals. Lastly, the increased pulmonary resistance due to pulmonary stenosis in ToF is comparable to increased pulmonary resistance in crocodilians due to the presence of an active valve proximal to the pulmonary valve. Some of these anatomical structures could potentially be adapted for palliative surgery in children with HLHS or ToF. Moreover, further investigating the underlying molecular signals responsible for the adaptive tissue responses seen in other species may also be useful for developing novel strategies for preventing some of the complications that occur after surgical repair in both of these CHDs.
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Affiliation(s)
- Emilia Mitova
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Carin Wittnich
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Department of Surgery, University of Toronto, Toronto, Ontario, Canada
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Slithering CSF: Cerebrospinal Fluid Dynamics in the Stationary and Moving Viper Boa, Candoia aspera. BIOLOGY 2021; 10:biology10070672. [PMID: 34356527 PMCID: PMC8301399 DOI: 10.3390/biology10070672] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 06/19/2021] [Accepted: 07/14/2021] [Indexed: 01/10/2023]
Abstract
Simple Summary The cerebrospinal fluid (CSF) flows through and around the central nervous system to nourish, cleanse, and support the brain and spinal cord. Though abnormalities of this CSF flow have been linked to multiple human neural diseases, little is known about the underlying mechanics of CSF flow. This study was designed to test the hypothesis that movement of the body’s trunk could cause CSF flow; hence, the study was conducted on a snake, an animal with prominent trunk movement. The results demonstrate that the resting snake has a CSF pressure profile that is very similar to what is seen in humans and other mammals, and that the CSF dynamics are changed during either artificial (manual) or natural (locomotor) movement of the snake’s body Abstract In the viper boa (Candoia aspera), the cerebrospinal fluid (CSF) shows two stable overlapping patterns of pulsations: low-frequency (0.08 Hz) pulses with a mean amplitude of 4.1 mmHg that correspond to the ventilatory cycle, and higher-frequency (0.66 Hz) pulses with a mean amplitude of 1.2 mmHg that correspond to the cardiac cycle. Manual oscillations of anesthetized C. aspera induced propagating sinusoidal body waves. These waves resulted in a different pattern of CSF pulsations with frequencies corresponding to the displacement frequency of the body and with amplitudes greater than those of the cardiac or ventilatory cycles. After recovery from anesthesia, the snakes moved independently using lateral undulation and concertina locomotion. The episodes of lateral undulation produced similar influences on the CSF pressure as were observed during the manual oscillations, though the induced CSF pulsations were of lower amplitude during lateral undulation. No impact on the CSF was found while C. aspera was performing concertina locomotion. The relationship between the propagation of the body and the CSF pulsations suggests that the body movements produce an impulse on the spinal CSF.
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Cramberg M, Greer S, Young BA. The functional morphology of the postpulmonary septum of the American alligator (Alligator mississippiensis). Anat Rec (Hoboken) 2021; 305:3055-3074. [PMID: 34128345 DOI: 10.1002/ar.24692] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 02/22/2021] [Accepted: 04/03/2021] [Indexed: 11/08/2022]
Abstract
The American alligator (Alligator mississippiensis) has a postpulmonary septum (PPS) that partitions the intracoelomic cavity. The PPS adheres to the capsule of the liver caudally and to the visceral pleura of the lung cranially; the ventrolateral portions of the PPS are invested with smooth muscle, the remainder is tendinous. Differential pressure transducers were used to record the intrathoracic (ITP) and intraperitoneal (IPP) pressures, and determine the transdiaphragmatic pressure (TDP). Each ventilatory pulse resulted in a pulse in ITP and a significantly lower pulse in IPP; meaning that a TDP was established, and that the pleural and peritoneal cavities were functionally isolated. The anesthetized alligators were tilted 30° head-up or head-down in order to displace the liver. Head-up rotations caused a significant increase in IPP, and a significant decrease in ITP (which became negative); head-down rotations produced the opposite effect. During these rotations, the PPS maintained opposite pressures (positive or negative) in the pleural and peritoneal cavities, and established TDPs greater than have been reported for some mammals. Two types of "breaths" were recorded during these experiments. The first was interpreted as a contraction of the diaphragmaticus muscle, which displaces the liver caudally; these breaths had the same effect as the head-up rotations. The second type of breath was interpreted as constriction of the thoracic and abdominal body walls; this type of breath produced pronounced, long-duration, roughly parallel, increases in ITP and IPP. The smooth muscle within the PPS is suggestive of higher-order adjustment or tuning of the PPS's tensile state.
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Affiliation(s)
- Michael Cramberg
- Department of Anatomy, Kirksville College of Osteopathic Medicine, AT Still University, Kirksville, Missouri, USA
| | - Skye Greer
- Department of Anatomy, Kirksville College of Osteopathic Medicine, AT Still University, Kirksville, Missouri, USA
| | - Bruce A Young
- Department of Anatomy, Kirksville College of Osteopathic Medicine, AT Still University, Kirksville, Missouri, USA
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Filogonio R, Dubansky BD, Dubansky BH, Wang T, Elsey RM, Leite CAC, Crossley DA. Arterial wall thickening normalizes arterial wall tension with growth in American alligators, Alligator mississippiensis. J Comp Physiol B 2021; 191:553-562. [PMID: 33629153 DOI: 10.1007/s00360-021-01353-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 01/21/2021] [Accepted: 01/28/2021] [Indexed: 01/21/2023]
Abstract
Arterial wall tension increases with luminal radius and arterial pressure. Hence, as body mass (Mb) increases, associated increases in radius induces larger tension. Thus, it could be predicted that high tension would increase the potential for rupture of the arterial wall. Studies on mammals have focused on systemic arteries and have shown that arterial wall thickness increases with Mb and normalizes tension. Reptiles are good models to study scaling because some species exhibit large body size range associated with growth, thus, allowing for ontogenetic comparisons. We used post hatch American alligators, Alligator mississippiensis, ranging from 0.12 to 6.80 kg (~ 60-fold) to investigate how both the right aortic arch (RAo) and the left pulmonary artery (LPA) change with Mb. We tested two possibilities: (i) wall thickness increases with Mb and normalizes wall tension, such that stress (stress = tension/thickness) remains unchanged; (ii) collagen content scales with Mb and increases arterial strength. We measured heart rate and systolic and mean pressures from both systemic and pulmonary circulations in anesthetized animals. Once stabilized alligators were injected with adrenaline to induce a physiologically relevant increase in pressure. Heart rate decreased and systemic pressures increased with Mb; pulmonary pressures remained unchanged. Both the RAo and LPA were fixed under physiological hydrostatic pressures and displayed larger radius, wall tension and thickness as Mb increased, thus, stress was independent from Mb; relative collagen content was unchanged. We conclude that increased wall thickness normalizes tension and reduces the chances of arterial walls rupturing in large alligators.
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Affiliation(s)
- Renato Filogonio
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, SP, 13565-905, Brazil.
| | - Benjamin D Dubansky
- Department of Biological Sciences, Developmental Integrative Biology Cluster, University of North Texas, Denton, TX, 76203-5220, USA
| | - Brooke H Dubansky
- Department of Medical Laboratory Sciences and Public Health, Tarleton State University, Fort Worth, TX, USA
| | - Tobias Wang
- Section for Zoophysiology, Department of Biosciences, Aarhus University, 8000, Aarhus C, Denmark
| | - Ruth M Elsey
- Louisiana Department of Wildlife and Fisheries, Rockefeller Wildlife Refuge, Grand Chenier, LA, 70643, USA
| | - Cléo A C Leite
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, SP, 13565-905, Brazil
| | - Dane A Crossley
- Department of Biological Sciences, Developmental Integrative Biology Cluster, University of North Texas, Denton, TX, 76203-5220, USA
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Young BA, Adams J, Beary JM, Mardal KA, Schneider R, Kondrashova T. Variations in the cerebrospinal fluid dynamics of the American alligator (Alligator mississippiensis). Fluids Barriers CNS 2021; 18:11. [PMID: 33712028 PMCID: PMC7953579 DOI: 10.1186/s12987-021-00248-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 03/04/2021] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Studies of mammalian CSF dynamics have been focused on three things: paravascular flow, pressure and pulsatility, and "bulk" flow; and three (respective) potential motive forces have been identified: vasomotor, cardiac, and ventilatory. There are unresolved questions in each area, and few links between the different areas. The American alligator (Alligator mississippiensis) has pronounced plasticity in its ventilatory and cardiovascular systems. This study was designed to test the hypothesis that the greater cardiovascular and ventilatory plasticity of A. mississippiensis would result in more variation within the CSF dynamics of this species. METHODS Pressure transducers were surgically implanted into the cranial subarachnoid space of 12 sub-adult alligators; CSF pressure and pulsatility were monitored along with EKG and the exhalatory gases. In four of the alligators a second pressure transducer was implanted into the spinal subarachnoid space. In five of the alligators the CSF was labeled with artificial microspheres and Doppler ultrasonography used to quantify aspects of the spinal CSF flow. RESULTS Both temporal and frequency analyses of the CSF pulsations showed highly variable contributions of both the cardiac and ventilatory cycles. Unlike the mammalian condition, the CSF pressure pulsations in the alligator are often of long (~ 3 s) duration, and similar duration CSF unidirectional flow pulses were recorded along the spinal cord. Reduction of the duration of the CSF pulsations, as during tachycardia, can lead to a "summation" of the pulsations. There appears to be a minimum duration (~ 1 s) of isolated CSF pulsations. Simultaneous recordings of cranial and spinal CSF pressures reveal a 200 ms delay in the propagation of the pressure pulse from the cranium to the vertebral canal. CONCLUSIONS Most of the CSF flow dynamics recorded from the alligators, are similar to what has been reported from studies of the human CSF. It is hypothesized that the link between ventilatory mechanics and CSF pulsations in the alligator is mediated by displacement of the spinal dura. The results of the study suggest that understanding the CSF dynamics of Alligator may provide unique insights into the evolutionary origins and functional regulation of the human CSF dynamics.
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Affiliation(s)
- Bruce A Young
- Department of Anatomy, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA.
| | - James Adams
- Department of Anatomy, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA
| | - Jonathan M Beary
- Behavioral Neuroscience, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA
| | | | - Robert Schneider
- Family Medicine, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA
| | - Tatyana Kondrashova
- Family Medicine, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA
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Manuel L, Freeman L, Nashef SA. Surgery for Eisenmenger syndrome: time for a rethink? J R Soc Med 2019; 112:512-513. [PMID: 31526213 DOI: 10.1177/0141076819877551] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Lucy Manuel
- Papworth Hospital NHS Foundation Trust, Cambridge CB2 0AY, UK
| | - Leisa Freeman
- Norfolk and Norwich University Hospital, Norwich NR4 7UY, UK
| | - Samer Am Nashef
- Papworth Hospital NHS Foundation Trust, Cambridge CB2 0AY, UK
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Young BA, Adams J, Segal S, Kondrashova T. Hemodynamics of tonic immobility in the American alligator (Alligator mississippiensis) identified through Doppler ultrasonography. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2018; 204:953-964. [PMID: 30259097 DOI: 10.1007/s00359-018-1293-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 09/11/2018] [Accepted: 09/21/2018] [Indexed: 11/28/2022]
Abstract
American alligators (Alligator mississippiensis) held inverted exhibit tonic immobility, combining unresponsiveness with flaccid paralysis. We hypothesize that inverting the alligator causes a gravitationally promoted increase in right aortic blood flowing through the foramen of Panizza, with a concurrent decrease in blood flow through the primary carotid, and thereby of cerebral perfusion. Inverting the alligator results in displacement of the liver, post-pulmonary septum, and the heart. EKG analysis revealed a significant decrease in heart rate following inversion; this decrease was maintained for approximately 45 s after inversion which is in general agreement with the total duration of tonic immobility in alligators (49 s). Doppler ultrasonography revealed that following inversion of the alligator, there was a reversal in direction of blood flow through the foramen of Panizza, and this blood flow had a significant increase in velocity (compared to the foraminal flow in the prone alligator). There was an associated significant decrease in the velocity of blood flow through the primary carotid artery once the alligator was held in the supine position. Tonic immobility in the alligator appears to be a form of vasovagal syncope which arises, in part, from the unique features of the crocodilian heart.
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Affiliation(s)
- Bruce A Young
- Department of Anatomy, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA.
| | - James Adams
- Department of Anatomy, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA
| | - Solomon Segal
- Department of Anatomy, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA
| | - Tatyana Kondrashova
- Department of Family Medicine, Preventitive Medicine, and Community Health, Kirksville College of Osteopathic Medicine, A.T. Still University, Kirksville, MO, 63501, USA
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Findsen A, Crossley DA, Wang T. Feeding alters blood flow patterns in the American alligator (Alligator mississippiensis). Comp Biochem Physiol A Mol Integr Physiol 2018; 215:1-5. [DOI: 10.1016/j.cbpa.2017.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 02/07/2017] [Accepted: 09/05/2017] [Indexed: 10/18/2022]
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INTRAMUSCULAR EPINEPHRINE RESULTS IN REDUCED ANESTHETIC RECOVERY TIME IN AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) UNDERGOING ISOFLURANE ANESTHESIA. J Zoo Wildl Med 2017; 48:55-61. [PMID: 28363062 DOI: 10.1638/2015-0293.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Inhalants are commonly used to anesthetize reptiles, but volatile anesthetics have been associated with prolonged recovery times. The objective of this study was to determine the effects of intramuscular (IM) epinephrine on anesthetic recovery times following isoflurane anesthesia in a population of subadult American alligators ( Alligator mississippiensis ). In this prospective randomized crossover study, five clinically healthy alligators were anesthetized for 90 min with the use of isoflurane. Alligators were randomly assigned into one of two treatment groups: Group E received IM epinephrine (0.1 mg/kg), and Group S received an equal volume of 0.9% saline administered after isoflurane was discontinued. Time from the end of inhalant administration to return of spontaneous ventilation, return of the palpebral reflex, movement in response to a standardized toe pinch, and spontaneous movement was recorded. The time of extubation was noted and occurred following the return of spontaneous ventilation and movement. Pulse rate, surface body temperature, and airway gases including expiratory and inspiratory isoflurane concentrations and end-tidal carbon dioxide were measured every 5 min throughout the study. The time from the end of anesthesia to extubation was significantly faster in Group E (51.2 ± 16.7 min) compared to Group S (107.4 ± 43.7 min). Pulse rate was significantly higher within the first 15 min following epinephrine injection compared to the saline group at these time points. Therefore, IM epinephrine administered at the end of general anesthesia can significantly hasten anesthetic recovery from isoflurane in alligators.
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Poelmann RE, Gittenberger-de Groot AC, Biermans MWM, Dolfing AI, Jagessar A, van Hattum S, Hoogenboom A, Wisse LJ, Vicente-Steijn R, de Bakker MAG, Vonk FJ, Hirasawa T, Kuratani S, Richardson MK. Outflow tract septation and the aortic arch system in reptiles: lessons for understanding the mammalian heart. EvoDevo 2017; 8:9. [PMID: 28491275 PMCID: PMC5424407 DOI: 10.1186/s13227-017-0072-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/03/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cardiac outflow tract patterning and cell contribution are studied using an evo-devo approach to reveal insight into the development of aorto-pulmonary septation. RESULTS We studied embryonic stages of reptile hearts (lizard, turtle and crocodile) and compared these to avian and mammalian development. Immunohistochemistry allowed us to indicate where the essential cell components in the outflow tract and aortic sac were deployed, more specifically endocardial, neural crest and second heart field cells. The neural crest-derived aorto-pulmonary septum separates the pulmonary trunk from both aortae in reptiles, presenting with a left visceral and a right systemic aorta arising from the unseptated ventricle. Second heart field-derived cells function as flow dividers between both aortae and between the two pulmonary arteries. In birds, the left visceral aorta disappears early in development, while the right systemic aorta persists. This leads to a fusion of the aorto-pulmonary septum and the aortic flow divider (second heart field population) forming an avian aorto-pulmonary septal complex. In mammals, there is also a second heart field-derived aortic flow divider, albeit at a more distal site, while the aorto-pulmonary septum separates the aortic trunk from the pulmonary trunk. As in birds there is fusion with second heart field-derived cells albeit from the pulmonary flow divider as the right 6th pharyngeal arch artery disappears, resulting in a mammalian aorto-pulmonary septal complex. In crocodiles, birds and mammals, the main septal and parietal endocardial cushions receive neural crest cells that are functional in fusion and myocardialization of the outflow tract septum. Longer-lasting septation in crocodiles demonstrates a heterochrony in development. In other reptiles with no indication of incursion of neural crest cells, there is either no myocardialized outflow tract septum (lizard) or it is vestigial (turtle). Crocodiles are unique in bearing a central shunt, the foramen of Panizza, between the roots of both aortae. Finally, the soft-shell turtle investigated here exhibits a spongy histology of the developing carotid arteries supposedly related to regulation of blood flow during pharyngeal excretion in this species. CONCLUSIONS This is the first time that is shown that an interplay of second heart field-derived flow dividers with a neural crest-derived cell population is a variable but common, denominator across all species studied for vascular patterning and outflow tract septation. The observed differences in normal development of reptiles may have impact on the understanding of development of human congenital outflow tract malformations.
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Affiliation(s)
- Robert E Poelmann
- Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, Leiden, The Netherlands.,Animal Sciences and Health, Sylvius Laboratories, University of Leiden, Sylviusweg 72, Leiden, The Netherlands
| | | | - Marcel W M Biermans
- Animal Sciences and Health, Sylvius Laboratories, University of Leiden, Sylviusweg 72, Leiden, The Netherlands
| | - Anne I Dolfing
- Animal Sciences and Health, Sylvius Laboratories, University of Leiden, Sylviusweg 72, Leiden, The Netherlands
| | - Armand Jagessar
- Animal Sciences and Health, Sylvius Laboratories, University of Leiden, Sylviusweg 72, Leiden, The Netherlands
| | - Sam van Hattum
- Animal Sciences and Health, Sylvius Laboratories, University of Leiden, Sylviusweg 72, Leiden, The Netherlands
| | - Amanda Hoogenboom
- Animal Sciences and Health, Sylvius Laboratories, University of Leiden, Sylviusweg 72, Leiden, The Netherlands
| | - Lambertus J Wisse
- Department of Anatomy and Embryology, Leiden University Medical Center, Einthovenweg 20, Leiden, The Netherlands
| | - Rebecca Vicente-Steijn
- Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, Leiden, The Netherlands.,Department of Anatomy and Embryology, Leiden University Medical Center, Einthovenweg 20, Leiden, The Netherlands
| | - Merijn A G de Bakker
- Animal Sciences and Health, Sylvius Laboratories, University of Leiden, Sylviusweg 72, Leiden, The Netherlands
| | - Freek J Vonk
- Animal Sciences and Health, Sylvius Laboratories, University of Leiden, Sylviusweg 72, Leiden, The Netherlands.,Naturalis Biodiversity Center, Darwinweg 2, Leiden, The Netherlands
| | - Tatsuya Hirasawa
- Laboratory for Evolutionary Morphology, RIKEN, 2-2-3 Minatojima-minami, Chuo-ku, Kobe, Hyogo 650-0047 Japan
| | - Shigeru Kuratani
- Laboratory for Evolutionary Morphology, RIKEN, 2-2-3 Minatojima-minami, Chuo-ku, Kobe, Hyogo 650-0047 Japan
| | - Michael K Richardson
- Animal Sciences and Health, Sylvius Laboratories, University of Leiden, Sylviusweg 72, Leiden, The Netherlands
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Alves AC, Ribeiro DBDC, Cotrin JV, Resende HRD, Drummond CD, Almeida FRD, Vicente Neto J, Sousa RVD. Descrição morfológica do coração e dos vasos da base do jacaré-do-pantanal (Caiman yacare Daudin, 1802) proveniente de zoocriadouro. PESQUISA VETERINÁRIA BRASILEIRA 2016. [DOI: 10.1590/s0100-736x2016001300002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Resumo: Com este estudo objetivou-se descrever os aspectos anatômicos e histológicos do coração do jacaré-do-pantanal (Caiman yacare), proveniente de zoocriadouro. Para tanto, estudou-se 13 exemplares da espécie, os quais foram perfundidos, conservados em solução de formaldeído a 10% e submetidos às técnicas anatômicas específicas. O coração foi separado e amostras foram colhidas e submetidas à avaliação histológica. Macroscopicamente o coração é tetracavitário, e além de dois átrios e dois ventrículos, apresenta uma estrutura denominada cone arterial, do qual emergem os vasos da base do coração. Foram identificadas duas aortas, direita e esquerda, sendo que a esquerda emerge do ventrículo direito e se comunica com o tronco sistêmico direito por meio do forame de Panizza. Histologicamente o coração possui epicárdio, miocárdio e endocárdio típicos. Concluímos que a histologia do coração, no jacaré-do-pantanal, é semelhante à de outras espécies de répteis. Contudo, anatomicamente apresenta particularidades importantes, as quais representam, possivelmente, adaptações que permitiram a perpetuação da espécie.
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Jensen B, Elfwing M, Elsey RM, Wang T, Crossley DA. Coronary blood flow in the anesthetized American alligator ( Alligator mississippiensis ). Comp Biochem Physiol A Mol Integr Physiol 2016; 191:44-52. [DOI: 10.1016/j.cbpa.2015.09.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 09/06/2015] [Accepted: 09/24/2015] [Indexed: 12/13/2022]
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Jensen B, Moorman AFM, Wang T. Structure and function of the hearts of lizards and snakes. Biol Rev Camb Philos Soc 2013; 89:302-36. [DOI: 10.1111/brv.12056] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 06/26/2013] [Accepted: 07/30/2013] [Indexed: 12/20/2022]
Affiliation(s)
- Bjarke Jensen
- Department of Bioscience, Zoophysiology; Aarhus University; Aarhus C 8000 Denmark
- Department of Anatomy, Embryology & Physiology, Academic Medical Center; University of Amsterdam; Amsterdam 1105 The Netherlands
| | - Antoon F. M. Moorman
- Department of Anatomy, Embryology & Physiology, Academic Medical Center; University of Amsterdam; Amsterdam 1105 The Netherlands
| | - Tobias Wang
- Department of Bioscience, Zoophysiology; Aarhus University; Aarhus C 8000 Denmark
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Jacobs K, Goy SK, Dzialowski EM. Morphology of the embryonic and hatchling american alligator ductus arteriosi and implications for embryonic cardiovascular shunting. J Morphol 2011; 273:186-94. [DOI: 10.1002/jmor.11015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 07/14/2011] [Accepted: 07/22/2011] [Indexed: 11/11/2022]
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Gardner MN, Sterba-Boatwright B, Jones DR. Ligation of the left aorta in alligators affects acid–base balance: A role for the R→L shunt. Respir Physiol Neurobiol 2011; 178:315-22. [DOI: 10.1016/j.resp.2011.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 06/30/2011] [Accepted: 07/01/2011] [Indexed: 11/25/2022]
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Elucidating the responses and role of the cardiovascular system in crocodilians during diving: Fifty years on from the work of C.G. Wilber. Comp Biochem Physiol A Mol Integr Physiol 2011; 160:1-8. [DOI: 10.1016/j.cbpa.2011.05.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 04/27/2011] [Accepted: 05/17/2011] [Indexed: 11/18/2022]
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Eme J, Gwalthney J, Owerkowicz T, Blank JM, Hicks JW. Turning crocodilian hearts into bird hearts: growth rates are similar for alligators with and without right-to-left cardiac shunt. ACTA ACUST UNITED AC 2010; 213:2673-80. [PMID: 20639429 DOI: 10.1242/jeb.042051] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The functional and possible adaptive significance of non-avian reptiles' dual aortic arch system and the ability of all non-avian reptiles to perform central vascular cardiac shunts have been of great interest to comparative physiologists. The unique cardiac anatomy of crocodilians - a four-chambered heart with the dual aortic arch system - allows for only right-to-left (R-L; pulmonary bypass) cardiac shunt and for surgical elimination of this shunt. Surgical removal of the R-L shunt, by occluding the left aorta (LAo) upstream and downstream of the foramen of Panizza, results in a crocodilian with an obligatory, avian/mammalian central circulation. In this study, R-L cardiac shunt was eliminated in age-matched, female American alligators (Alligator mississippiensis; 5-7 months of age). We tested the hypothesis that surgical elimination of R-L cardiac shunt would impair growth (a readily measured proxy for fitness) compared with sham-operated, age-matched controls, especially in animals subjected to exhaustive exercise. While regular exercise caused a decrease in size (snout-to-vent length, head length and body mass), elimination of the capacity for R-L cardiac shunt did not greatly reduce animal growth, despite a chronic ventricular enlargement in surgically altered juvenile alligators. We speculate that, despite being slightly smaller, alligators with an occluded LAo would have reached sexual maturity in the same breeding season as control alligators. This study suggests that crocodilian R-L cardiac shunt does not provide an adaptive advantage for juvenile alligator growth and supports the logic that cardiac shunts persist in crocodilians because they have not been selected against.
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Affiliation(s)
- John Eme
- University of California, Irvine, Ecology and Evolutionary Biology, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA.
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Bertens LMF, Richardson MK, Verbeek FJ. Analysis of cardiac development in the turtle Emys orbicularis (Testudines: Emidydae) using 3-D computer modeling from histological sections. Anat Rec (Hoboken) 2010; 293:1101-14. [PMID: 20583255 DOI: 10.1002/ar.21162] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
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 responsible 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 material in such an interactive way, we hope to make optimal use of the new 3-D reconstruction techniques and to engage the reader in a more direct manner.
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Affiliation(s)
- Laura M F Bertens
- Leiden Institute of Advanced Computer Science, Leiden University, Leiden, The Netherlands
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Eme J, Gwalthney J, Blank JM, Owerkowicz T, Barron G, Hicks JW. Surgical removal of right-to-left cardiac shunt in the American alligator (Alligator mississippiensis) causes ventricular enlargement but does not alter apnoea or metabolism during diving. ACTA ACUST UNITED AC 2010; 212:3553-63. [PMID: 19837897 DOI: 10.1242/jeb.034595] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Crocodilians have complete anatomical separation between the ventricles, similar to birds and mammals, but retain the dual aortic arch system found in all non-avian reptiles. This cardiac anatomy allows surgical modification that prevents right-to-left (R-L) cardiac shunt. A R-L shunt is a bypass of the pulmonary circulation and recirculation of oxygen-poor blood back to the systemic circulation and has often been observed during the frequent apnoeic periods of non-avian reptiles, particularly during diving in aquatic species. We eliminated R-L shunt in American alligators (Alligator mississippiensis) by surgically occluding the left aorta (LAo; arising from right ventricle) upstream and downstream of the foramen of Panizza (FoP), and we tested the hypotheses that this removal of R-L shunt would cause afterload-induced cardiac remodelling and adversely affect diving performance. Occlusion of the LAo both upstream and downstream of the FoP for approximately 21 months caused a doubling of RV pressure and significant ventricular enlargement (average approximately 65%) compared with age-matched, sham-operated animals. In a separate group of recovered, surgically altered alligators allowed to dive freely in a dive chamber at 23 degrees C, occlusion of the LAo did not alter oxygen consumption or voluntary apnoeic periods relative to sham animals. While surgical removal of R-L shunt causes considerable changes in cardiac morphology similar to aortic banding in mammals, its removal does not affect the respiratory pattern or metabolism of alligators. It appears probable that the low metabolic rate of reptiles, rather than pulmonary circulatory bypass, allows for normal aerobic dives.
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Affiliation(s)
- John Eme
- Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA.
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Jones D, Gardner M. Ring around the heart: an unusual feature of the crocodilian central circulatory system. ACTA ACUST UNITED AC 2010. [DOI: 10.7882/az.2010.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Furtado-Filho OV, Polcheira C, Machado DP, Mourão G, Hermes-Lima M. Selected oxidative stress markers in a South American crocodilian species. Comp Biochem Physiol C Toxicol Pharmacol 2007; 146:241-254. [PMID: 17383940 DOI: 10.1016/j.cbpc.2006.11.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2006] [Revised: 11/10/2006] [Accepted: 11/14/2006] [Indexed: 10/23/2022]
Abstract
Crocodilians and other diving vertebrates experience hypoperfusion and hypoxia of several internal organs during long dives. At the end of a dive, reperfusion of aerated blood may cause a physiologically relevant oxidative stress. In this study, we analyzed selected markers of oxidative stress in eight organs of normoxic Paraguayan caiman (Caiman yacare) captured in the Brazilian Pantanal wetlands during the winter of 2001 (six mature-adult males and eight young-adult males; AD-1 and YA-1 groups, respectively), and during the summer of 2002 (six young-adult males (YA-2 group), ten hatchlings and five embryos). Lipid peroxidation products determined by three different assays were generally highest in brain, liver and kidney (in comparison with all other organs), and lowest in white muscles from the tail and hind legs. Liver and kidney showed the highest levels of carbonyl protein, while brain showed low levels. Intermediate levels of oxidative stress markers were mostly found in the heart ventricles and lung. Differences in oxidative stress markers between AD-1 and YA-1 were organ-specific, showing no age-related correlation. However, most oxidative stress markers in YA-2 organs were either higher than (by 1.4- to 3.7-fold) or not significantly different from respective values in hatchlings organs. This pattern (hatchlings versus young-adults) was confirmed using correlation analysis of individual caiman size versus levels of oxidative damage markers in four organs. The higher level of oxidative stress markers in young-adults possibly relates to the fast growth rate (and thus, increased oxidative metabolic rate) of C. yacare in the first years of life. Differences in oxidative stress markers between YA-1 and YA-2 were also observed and were ascribed to seasonal changes in free radical metabolism. These results in normoxic C. yacare represent the first step towards understanding the age-related physiological oxidative stress of a diving reptile from a seasonally changing wetland environment.
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Affiliation(s)
- Orlando V Furtado-Filho
- Oxyradical Research Group, Departamento de Biologia Celular, Universidade de Brasília, Brasília, DF 70910-900, Brazil; PPG Biologia Molecular, Universidade de Brasília, Brasília, DF 70910-900, Brazil; Colégio Militar de Porto Alegre, Brazilian Army, Porto Alegre, RS, 90040-130, Brazil
| | - Cássia Polcheira
- Oxyradical Research Group, Departamento de Biologia Celular, Universidade de Brasília, Brasília, DF 70910-900, Brazil; Escola Superior de Ciências da Saúde, FEPECS, Brasília, DF 70710-907, Brazil
| | - Daniel P Machado
- PPG Biologia Molecular, Universidade de Brasília, Brasília, DF 70910-900, Brazil
| | - Guilherme Mourão
- Laboratório de Vida Selvagem, Embrapa Pantanal, Corumbá, MS 79320-900, Brazil
| | - Marcelo Hermes-Lima
- Oxyradical Research Group, Departamento de Biologia Celular, Universidade de Brasília, Brasília, DF 70910-900, Brazil.
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Abstract
The crocodilian spinal vein is remarkably robust yet historically overlooked. Using corrosion casting, we describe the anatomy of this vessel and its connections with the caval and hepatic venous systems in representatives from four crocodilian genera. The spinal vein arises from an enlarged occipital sinus over the medulla and extends the entire length of the vertebral column. Unlike in squamate reptiles, the spinal vein is single (nonplexiform), voluminous, and situated dorsal to the spinal cord, and plexi lateral to the cord span between emerging intercostal veins. The connections with the other venous systems are otherwise similar to those in other tetrapods. The overall anatomy of this vessel and its abundant connections with the other venous systems indicate it likely plays a primary role in returning blood to the heart from all parts of the body. Preliminary studies of function suggest that this vessel could also play an adaptive role during basking and diving.
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Affiliation(s)
- Kevin C Zippel
- Department of Zoology, University of Florida, Gainesville, FL 32611, USA.
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30
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Syme DA, Gamperl K, Jones DR. Delayed depolarization of the cog-wheel valve and pulmonary-to-systemic shunting in alligators. J Exp Biol 2002; 205:1843-51. [PMID: 12077160 DOI: 10.1242/jeb.205.13.1843] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYAlligators and other crocodilians have a cog-wheel valve located within the subpulmonary conus, and active closure of this valve during each heart beat can markedly and phasically increase resistance in the pulmonary outflow tract. If this increased resistance causes right ventricular pressure to rise above that in the systemic circuit, right ventricular blood can flow into the left aorta and systemic circulation, an event known as pulmonary-to-systemic shunting. To understand better how this valve is controlled, anaesthetized American alligators (Alligator mississippiensis) were used to examine the relationships between depolarization of the right ventricle,depolarization/contraction of the cog-wheel valve muscle and the resultant right ventricular, pulmonary artery and systemic pressures. Depolarization swept across the right ventricle from the apex towards the base (near where the cog-wheel valve muscle is located) at a velocity of 91±23 cm s-1 (mean ± S.E.M., N=3). The cog-wheel valve electrocardiogram (ECG) (and thus contraction of the valve) trailed the right ventricular ECG by 248±28 ms (N=3), which was equivalent to 6-35 % of a cardiac cycle. This long interval between right ventricular and valve depolarization suggests a nodal delay at the junction between the base of the right ventricle and the cog-wheel valve. The delay before valve closure determined when the abrupt secondary rise in right ventricular pressure occurred during systole and is likely to strongly influence the amount of blood entering the pulmonary artery and thus to directly control the degree of shunting. Left vagal stimulation (10-50 Hz) reduced the conduction delay between the right ventricle and cog-wheel valve by approximately 20 % and reduced the integrated cog-wheel ECG by 10-20 %. Direct application of acetylcholine (1-2 mg) also reduced the integrated cog-wheel ECG by 10-100 %;however, its effect on the conduction delay was highly variable (-40 to +60%). When the cog-wheel valve muscle was killed by the application of ethanol,the cog-wheel ECG was absent, right ventricular and pulmonary pressures remained low and tracked one another, the secondary rise in right ventricular pressure was abolished and shunting did not occur. This study provides additional, direct evidence that phasic contraction of the cog-wheel valve muscle controls shunting, that nervous and cholinergic stimulation can alter the delay and strength of valve depolarization and that this can affect the propensity to shunt.
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Affiliation(s)
- Douglas A Syme
- Department of Biological Sciences, 2500 University Drive NW, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
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31
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Affiliation(s)
- M Axelsson
- Department of Zoology, Göteborg University, PO Box 463, SE-40530 Göteborg, Sweden.
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32
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Affiliation(s)
- C E Franklin
- Department of Zoology and Entomology, University of Queensland, Brisbane, Australia.
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33
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Axelsson M, Franklin CE. From Anatomy to Angioscopy: 164 Years of Crocodilian Cardiovascular Research, Recent Advances, and Speculations. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0300-9629(96)00255-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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