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Gantner L, Portier K, Quintard B. Comparison of intramuscular alfaxalone with medetomidine-ketamine for inducing anaesthesia in Trachemys scripta spp. undergoing sterilization. Vet Anaesth Analg 2023; 50:421-429. [PMID: 37507249 DOI: 10.1016/j.vaa.2023.06.006] [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: 03/03/2022] [Revised: 04/27/2023] [Accepted: 06/28/2023] [Indexed: 07/30/2023]
Abstract
OBJECTIVE To compare the effect of two anaesthetic protocols on heart rate (HR), time to muscle relaxation and tracheal intubation and time to surgical plane of anaesthesia, in Trachemys scripta spp. undergoing oophorectomy. STUDY DESIGN Prospective randomized clinical study. ANIMALS A total of 43 healthy female turtles. METHODS Morphine (1.5 mg kg-1) was injected subcutaneously 2 hours before anaesthesia induction. The turtles were randomly administered either medetomidine (0.2 mg kg-1) and ketamine (10 mg kg-1) (group MK; n = 23) or alfaxalone (20 mg kg-1) (group A; n = 20) intramuscularly followed by bupivacaine (2 mg kg-1) administered subcutaneously along the incision site. Anaesthesia was maintained with isoflurane delivered in oxygen (100%). HR and the anaesthetic depth score (ADS) were recorded every 5 minutes from induction to recovery. A Friedman test followed by Wilcoxon tests with Bonferroni adjustment were used to compare these non-parametric data (HR and ADS) between groups and over time. Time to muscle relaxation of neck and limbs (TMR), tracheal tube insertion (TTTI) and stage of surgical anaesthesia (TADS≤3) were recorded and compared between groups using a Welch's t test after logarithmic transformation. RESULTS Median values of TMR, TTTI and TADS≤3 were 4, 9.5 and 25 minutes in group A, respectively, and 14, 20 and 35 minutes in group MK (TMR, TTTIp ≤ 0.0001; TADS≤3p = 0.001). Plane of anaesthesia was significantly deeper in group A than in group MK for the first 20 minutes (p < 0.01). HR at 10 and 15 minutes post injection was significantly lower in group MK (28 beats minute-1) than in group A (36 and 34 beats minute-1) (p < 0.02). CONCLUSIONS AND CLINICAL RELEVANCE After intramuscular injection in Trachemys scripta spp., tracheal intubation, muscle relaxation and a surgical plane of anaesthesia developed faster with alfaxalone than medetomidine-ketamine.
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Affiliation(s)
- Laurène Gantner
- VetAgro Sup, Université de Lyon, Lyon, France; Parc Zoologique & Botanique de Mulhouse, Mulhouse, France; Espace Zoologique, Saint Martin la Plaine, France.
| | - Karine Portier
- VetAgro Sup, Université de Lyon, Lyon, France; CarMeN Laboratory, INSERM, INRA, INSA Lyon, Université Claude Bernard Lyon 1, Univ Lyon, Lyon, France
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Kristensen L, Zardo JQ, Hansen SM, Bertelsen MF, Alstrup AKO, Wang T, Williams CJA. Effect of atropine and propofol on the minimum anaesthetic concentration of isoflurane in the freshwater turtle Trachemys scripta (yellow-bellied slider). Vet Anaesth Analg 2023; 50:180-187. [PMID: 36739261 DOI: 10.1016/j.vaa.2021.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 10/06/2021] [Accepted: 10/27/2021] [Indexed: 12/05/2022]
Abstract
OBJECTIVE To determine if the administration of atropine would reduce the measured minimum anaesthetic concentration of isoflurane (MACisoflurane) in freshwater turtles - the yellow-bellied slider (Trachemys scripta scripta). STUDY DESIGN Paired, blinded, randomized, prospective studies of 1) the effect of atropine in isoflurane anaesthetized freshwater turtles (T. scripta scripta) and 2) the effect of atropine in yellow-bellied sliders in which anaesthesia was induced with propofol and maintained with isoflurane. ANIMALS T. scripta scripta (n = 8), female, adult. METHODS Atropine (2 mg kg-1) or an isovolumetric control injection of saline was administered intraperitoneally 15 minutes prior to induction of anaesthesia with isoflurane. Individual MACisoflurane was then determined by end-tidal gas analysis in a bracketing design by an experimenter blinded to the administered drug, with a 2 week washout period. The experiment was repeated, with atropine (2 mg kg-1) or saline administered intravascularly in combination with propofol for anaesthetic induction. Linear mixed modelling was used to determine the effects of atropine and propofol on the individual MACisoflurane. Data are presented as mean ± standard deviation. RESULTS Premedication with atropine significantly reduced MACisoflurane (p = 0.0039). In isoflurane-induced T. scripta scripta, MACisoflurane decreased from 4.2 ± 0.4% to 3.3 ± 0.8% when atropine had been administered. Propofol as an induction agent had a MAC-sparing effect (p < 0.001) such that MACisoflurane following propofol and a control injection of saline was 2.3 ± 1.0%, which decreased further to 1.5 ± 0.8% when propofol was combined with atropine. CONCLUSIONS AND CLINICAL RELEVANCE Atropine, presumably by inhibiting parasympathetically mediated pulmonary artery constriction, decreases right-to-left cardiac shunting and the MACisoflurane in yellow-bellied sliders, and thereby may facilitate control of inhalant anaesthesia. Propofol can be used for induction of anaesthesia and reduces the required concentration of inhaled anaesthesia assessed 1.5 hours following induction.
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Affiliation(s)
- Line Kristensen
- Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark
| | - Juliana Q Zardo
- School of Veterinary Medicine and Animal Science, Copenhagen University, Copenhagen, Denmark
| | - Sofie M Hansen
- School of Veterinary Medicine and Animal Science, Copenhagen University, Copenhagen, Denmark
| | - Mads F Bertelsen
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Denmark
| | - Aage K O Alstrup
- Department of Nuclear Medicine & PET, Aarhus University Hospital, Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Tobias Wang
- Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark
| | - Catherine J A Williams
- Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark; Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
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Sevoflurane sparing effect of morphine in tegus (Salvator merianae) – a preliminary study. Top Companion Anim Med 2022; 50:100678. [DOI: 10.1016/j.tcam.2022.100678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 04/14/2022] [Accepted: 06/01/2022] [Indexed: 11/24/2022]
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Obesity prolongs induction times in reptiles. Comp Biochem Physiol A Mol Integr Physiol 2022; 271:111255. [PMID: 35659976 DOI: 10.1016/j.cbpa.2022.111255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 05/24/2022] [Accepted: 05/30/2022] [Indexed: 11/22/2022]
Abstract
Obesity is common in captive reptiles, and reptiles are increasingly popular as companion animals and in physiological research. Obesity may present a challenge during surgical procedures using inhalation anaesthesia, as the long induction time due to the low reptilian metabolism may increase anaesthetic accumulation in the adipose tissues. This study investigated the impact of obesity on induction and recovery times from inhaled anaesthesia. The temporal change in the partial pressure of isoflurane in different tissues was predicted using a multi-compartment model. Furthermore, as right-to-left shunting can delay anaesthetic uptake and washout, we included an assessment of the combination of cardiac shunting and obesity. The model predictions indicate a clear increase in time to reach 90% equilibration of administered anaesthetic in the brain (T90) of obese non-shunting (lean 47 min, obese >100 min) and shunting (lean 81 min, obese >100 min) reptiles. The combination of obesity and shunting doubled the time to acquisition of mean anaesthetic concentration (a measure used to plan anaesthesia) from 8 min to 19 min. Adipose blood flow highly affected whether the body type had an impact on induction time, with low adipose blood flow abolishing the effect of body type. As T90 was never reached within 100 min with both the obese reptiles, it was not possible to conclude on the effect of obesity on recovery times within this study. Care should therefore be taken when anaesthetising obese reptiles for surgical purposes, to ensure adequate anaesthetic depth is attained, and recovery monitored closely.
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Abstract
Anesthetic management of chelonians represents a unique challenge; the order Chelonia includes numerous species that display diverse anatomic features, habitats, body sizes, temperaments, and metabolic rates. Owing to their peculiar characteristics, safe and effective sedation and anesthesia may be more complicated than in other animals. For example, gas inductions are not indicated, and intravenous catheterization requires practice. The pharmacology of anesthetic drugs is severely impacted by body/environmental temperature, site of administration, and organ function. This review will summarize the current knowledge in terms of anatomy, physiology, and drug metabolism in chelonians, before discussing practical aspects of anesthesia.
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Affiliation(s)
- Stefania Scarabelli
- Clinica Veterinaria Malpensa-Anicura, Via G. Marconi 27, Samarate, VA 21017, Italy
| | - Nicola Di Girolamo
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Oklahoma State University, 2065 West Farm Road, Stillwater, OK 74078, USA.
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Sedation and Anesthesia of Galapagos ( Chelonoidis nigra), Aldabra ( Aldabrachelys gigantea), and African Spurred Tortoises ( Centrochelys sulcata): A Retrospective Review (2009-2019). Animals (Basel) 2021; 11:ani11102920. [PMID: 34679940 PMCID: PMC8532946 DOI: 10.3390/ani11102920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/05/2021] [Accepted: 10/07/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Anesthesia is often required for the medical management of large tortoise species, but little has been published regarding effective anesthetic regimens for these species. The purpose of this study was to review anesthetic regimens that have been used safely and effectively in Galapagos (Chelonoidis nigra), Aldabra (Aldabrachelys gigantea), and African spurred (Centrochelys sulcata) tortoises, with the aim of improving medical management. Abstract Tortoises belong to the taxonomic family Testudinidae, which is considered one of the most imperiled families of the order Testudines. Anesthesia is often required for the medical and surgical management of large tortoises. The objectives of this retrospective study were to review drug regimens used to successfully anesthetize Galapagos (Chelonoidis nigra), Aldabra (Aldabrachelys gigantea) and African spurred (Centrochelys sulcata) tortoises, and to compare the times to effect and to extubation in tortoises administered different premedication protocols. Anesthetic records of giant tortoises admitted to the University of Florida College of Veterinary Medicine between January 2009 and December 2019 were reviewed. A total of 34 tortoises (six Aldabra, 23 Galapagos, and five African spurred) were included, resulting in 64 anesthetic events. Frequently used premedication protocols included an α2-adrenergic agonist and ketamine combined with either midazolam (group α2−adrenergic agonist, midazolam, ketamine, AMK; n = 34), a μ-opioid receptor agonist (group α2−adrenergic agonist, μ-opioid receptor agonist, ketamine, AOK; n = 13), or a μ−opioid receptor agonist and midazolam (group α2−adrenergic agonist, midazolam, μ-opioid receptor agonist, ketamine, AMOK; n = 10). Inhalant anesthetics (isoflurane, n = 21; sevoflurane, n = 23) were frequently used for maintenance of anesthesia following premedication. Out of the 34 total tortoises, 22 had only one anesthetic event, five had two anesthetic events, three had three anesthetic events, and four had four or more anesthetic events. Few adverse effects were observed and there was no mortality reported during the peri-anesthetic period. Sedation and general anesthesia of giant tortoises can be successfully performed with a combination of an α2-adrenergic agonist and ketamine in combination with midazolam and/or a μ−opioid receptor agonist.
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Williams CJA, Hansen K, Williams N, Jakobsen SR, Pedersen CCE, Bertelsen MF, Wang T. The influence of assisted ventilation and recumbency on cardiorespiratory physiology in the anesthetized freshwater turtle Trachemys scripta scripta. Comp Biochem Physiol A Mol Integr Physiol 2021; 260:111036. [PMID: 34256130 DOI: 10.1016/j.cbpa.2021.111036] [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: 02/25/2021] [Revised: 06/15/2021] [Accepted: 07/08/2021] [Indexed: 11/18/2022]
Abstract
The use of assisted ventilation is required in anesthetized reptiles as their respiratory drive is lost at surgical depths of anesthesia. The minute volume of the assisted ventilation influences arterial blood gases and acid-base regulation. Meanwhile, the ventilatory pattern may also affect hemodynamics in chelonians, which, given their large capacity for cardiac shunts, may impact the efficacy of the ventilation in terms of gas exchange. Hence, there is a need for primary information on the influence of assisted ventilation on chelonian physiology, and we, therefore, performed a randomized study into the effects of recumbency and maximum airway pressure on pressure-cycled ventilation in nine female Trachemys scripta scripta. Pronounced effects of ventilation pressure on arterial PCO2 and pH regardless of recumbency were revealed, whilst dorsal recumbency led to a larger Arterial-alveolar (A-a) O2 difference, suggesting compromised pulmonary gas exchange. Plasma [Na+] and [K+] balance was also significantly correlated with maximum airway pressure. Computed tomography (CT) scanning at a range of end-inspiratory pressures and ventral and dorsal recumbencies in eight T. scripta scripta showed that lung volumes increase with maximum ventilatory pressure, while recumbency did not influence volume at pressures above 5 cmH2O. Static compliance of the lungs was influenced by recumbency at neutral pressures. In conclusion, dorsal recumbency reduces pulmonary efficacy during positive pressure ventilation and tends to lower lung volume when ventilation is not provided. However, lung volumes and function - even in dorsal recumbency - can be adequately supported by assisted ventilation, and an end inspiratory pressure of 10 cmH2O at 4 breaths min-1 provided the most physiologically appropriate ventilation of anesthetized T. scripta scripta.
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Affiliation(s)
- Catherine J A Williams
- Zoophysiology, Department of Biology, Aarhus University, Denmark; Department of Biomedical Sciences, University of Guelph, Canada.
| | - Kasper Hansen
- Zoophysiology, Department of Biology, Aarhus University, Denmark; Department of Forensic Medicine, Aarhus University, Denmark; Department of Clinical Medicine (Comparative Medicine Lab), Aarhus University, Denmark
| | - Natasha Williams
- Zoophysiology, Department of Biology, Aarhus University, Denmark
| | | | | | | | - Tobias Wang
- Zoophysiology, Department of Biology, Aarhus University, Denmark
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Studer K, Di Girolamo N. Respiratory Disorders in Chelonians. Vet Clin North Am Exot Anim Pract 2021; 24:341-367. [PMID: 33892891 DOI: 10.1016/j.cvex.2021.01.004] [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: 11/27/2022]
Abstract
"Respiratory tract disease in chelonians can be difficult to treat and as such proper diagnostics are paramount. Infectious agents that can affect the respiratory tract of chelonians include viral, bacterial, fungal, and parasitic organisms. Noninfectious diseases can also develop. Because chelonians lack a proper diaphragm, changes in size of celomic organs can cause compression of the respiratory system. These conditions result in clinical signs that could be attributed to the respiratory system, such as open-mouth breathing. In this article, anatomy, physiology, and current standards for diagnostics and treatments of major diseases of the respiratory tract in chelonians are discussed."
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Affiliation(s)
- Kelsea Studer
- Oklahoma State University, Center for Veterinary Health Sciences, 2065 West Farm Road, Stillwater, OK 74078, USA
| | - Nicola Di Girolamo
- Oklahoma State University, Center for Veterinary Health Sciences, 2065 West Farm Road, Stillwater, OK 74078, USA.
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Kane LP, Chinnadurai SK, Vivirito K, Strahl-Heldreth D, Allender MC. Comparison of isoflurane, sevoflurane, and desflurane as inhalant anesthetics in prairie rattlesnakes ( Crotalus viridis). J Am Vet Med Assoc 2021; 257:945-949. [PMID: 33064609 DOI: 10.2460/javma.257.9.945] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To characterize induction and recovery characteristics of 3 commonly used inhalant anesthetics in prairie rattlesnakes (Crotalus viridis): isoflurane, sevoflurane, and desflurane. ANIMALS 12 healthy adult prairie rattlesnakes. PROCEDURES In a randomized crossover design, snakes underwent anesthetic induction with 5% isoflurane, 8% sevoflurane, or 18% desflurane, with a washout period of ≥ 7 days between anesthetic events. Anesthetic depth parameters were recorded throughout induction and recovery, including time to loss and return of righting reflex, muscle tone, ability to intubate, response to pressure, and time to return to spontaneous respiration. Every 5 minutes throughout the anesthetic procedures, heart rate, respiratory rate, and percentage expired anesthetic gas were recorded. RESULTS No snakes died during the study. Sevoflurane anesthesia resulted in anesthetic gas avoidance behavior in snakes during induction and had the significantly longest recovery time to extubation and time to return of pressure response, compared with the other inhalant anesthetics. Anesthesia with isoflurane resulted in a significantly longer time to return of righting reflex, compared with sevoflurane or desflurane. No significant difference was noted in time to loss of pressure response among the 3 anesthetic gases. Desflurane anesthesia resulted in the significantly quickest loss of righting reflex among the anesthetic protocols; despite this, 4 of 12 desflurane anesthetized snakes did not achieve an anesthetic plane deep enough for intubation. CONCLUSIONS AND CLINICAL RELEVANCE Isoflurane and sevoflurane, but not desflurane, inhalation anesthesia resulted in consistent and predictable loss of righting reflex and induction of anesthesia deep enough to allow intubation in snakes.
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Williams CJA, Malte CL, Malte H, Bertelsen MF, Wang T. Ectothermy and cardiac shunts profoundly slow the equilibration of inhaled anaesthetics in a multi-compartment model. Sci Rep 2020; 10:17157. [PMID: 33051496 PMCID: PMC7555730 DOI: 10.1038/s41598-020-74014-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 09/21/2020] [Indexed: 01/08/2023] Open
Abstract
The use of inhalational anaesthesia is ubiquitous in terrestrial vertebrates. Given the dependence of these agents on delivery by the cardiorespiratory system, we developed a new computational model predicting equilibration of inhaled anaesthetics in mammalian and ectotherm conditions including the ability of reptiles to maintain vascular shunts. A multi-compartment model was constructed from simultaneously-solved equations, verified by comparison to the literature for endo and ectotherm physiology. The time to 90% equilibration of anaesthetic in arterial blood (t90) is predicted and used to compare anaesthetics and physiologies. The five to tenfold lower cardiac output and minute ventilation of ectothermic vertebrates is predicted to slow equilibration times by five to ten times leading to 90% equilibration in ectotherm arterial blood of over 200 min, compounded by reduction in body temperature, and the extent of right-to-left vascular shunts. The impact of these findings is also influenced by the solubility coefficient of the anaesthetic, such that at net right-to-left shunt fractions of over 0.8, sevoflurane loses the advantage of faster equilibration, in comparison with isoflurane. We explore clinical strategies to regulate anaesthetic uptake in ectotherms by managing convectional flow especially by supportive ventilation and reduction of the right-to-left shunt.
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Affiliation(s)
- Catherine J A Williams
- Section of Zoophysiology, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark. .,Center for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, 2000, Frederiksberg, Denmark. .,Ontario Veterinary College, University of Guelph, 50 Stone Road E, Guelph, ON, N1G 2W1, Canada.
| | - Christian Lind Malte
- Section of Zoophysiology, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark
| | - Hans Malte
- Section of Zoophysiology, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark
| | - Mads F Bertelsen
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, 2000, Frederiksberg, Denmark
| | - Tobias Wang
- Section of Zoophysiology, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark.,Aarhus Institute of Advanced Sciences, Aarhus University, 8000, Aarhus C, Denmark
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Smith B, Crossley JL, Elsey RM, Hicks JW, Crossley DA. Embryonic developmental oxygen preconditions cardiovascular functional response to acute hypoxic exposure and maximal β-adrenergic stimulation of anesthetized juvenile American alligators ( Alligator mississippiensis). ACTA ACUST UNITED AC 2019; 222:jeb.205419. [PMID: 31548289 DOI: 10.1242/jeb.205419] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 09/16/2019] [Indexed: 12/31/2022]
Abstract
The effects of the embryonic environment on juvenile phenotypes are widely recognized. We investigated the effect of embryonic hypoxia on the cardiovascular phenotype of 4-year-old American alligators (Alligator mississippiensis). We hypothesized that embryonic 10% O2 preconditions cardiac function, decreasing the reduction in cardiac contractility associated with acute 5% O2 exposure in juvenile alligators. Our findings indicate that dobutamine injections caused a 90% increase in systolic pressure in juveniles that were incubated in 21% and 10% O2, with the 10% O2 group responding with a greater rate of ventricular relaxation and greater left ventricle output compared with the 21% O2 group. Further, our findings indicate that juvenile alligators that experienced embryonic hypoxia have a faster rate of ventricular relaxation, greater left ventricle stroke volume and greater cardiac power following β-adrenergic stimulation, compared with juvenile alligators that did not experience embryonic hypoxia. When juveniles were exposed to 5% O2 for 20 min, normoxic-incubated juveniles had a 50% decline in left ventricle maximal rate of pressure development and maximal pressure; however, these parameters were unaffected and decreased less in the hypoxic-incubated juveniles. These data indicate that embryonic hypoxia in crocodilians alters the cardiovascular phenotype, changing the juvenile response to acute hypoxia and β-adrenergic stimulation.
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Affiliation(s)
- Brandt Smith
- Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
| | - Janna L Crossley
- Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
| | - Ruth M Elsey
- Louisiana Department of Wildlife and Fisheries, Rockefeller Wildlife Refuge, Grand Chenier, LA 70643, USA
| | - James W Hicks
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Dane A Crossley
- Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
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Williams CJA, Greunz EM, Ringgaard S, Hansen K, Bertelsen MF, Wang T. Magnetic resonance imaging (MRI) reveals high cardiac ejection fractions in red-footed tortoises ( Chelonoidis carbonarius). ACTA ACUST UNITED AC 2019; 222:jeb.206714. [PMID: 31439654 DOI: 10.1242/jeb.206714] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 08/14/2019] [Indexed: 12/28/2022]
Abstract
The ejection fraction of the trabeculated cardiac ventricle of reptiles has not previously been measured. Here, we used the gold standard clinical methodology - electrocardiogram-gated flow magnetic resonance imaging (MRI) - to validate stroke volume measurements and end diastolic ventricular blood volume. This produced an estimate of ejection fraction in our study species, the red footed tortoise Chelonoidis carbonarius (n=5), under isoflurane anaesthesia of 88±11%. After reduction of the prevailing right-to-left intraventricular shunt through the action of atropine, the ejection fraction was 96±6%. This methodology opens new avenues for studying the complex hearts of ectotherms, and validating hypotheses on the function of a more highly trabeculated heart than that of endotherms, which have lower ejection fractions.
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Affiliation(s)
- Catherine J A Williams
- Section of Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark .,Center for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, 2000 Frederiksberg, Denmark
| | - Eva M Greunz
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, 2000 Frederiksberg, Denmark
| | - Steffen Ringgaard
- MR Research Center, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Blv. 99, 8200 Aarhus N, Denmark
| | - Kasper Hansen
- Section of Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark.,Comparative Medicine Lab, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Blv. 99, 8200 Aarhus N, Denmark.,Department of Forensic Medicine, Aarhus University Hospital, Palle Juul-Jensens Blv. 99, 8200 Aarhus N, Denmark
| | - Mads F Bertelsen
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, 2000 Frederiksberg, Denmark
| | - Tobias Wang
- Section of Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark.,Aarhus Institute of Advanced Sciences, Aarhus University, 8000 Aarhus C, Denmark
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Larouche CB, Mosley C, Beaufrère H, Dutton C. Effects of midazolam and nitrous oxide on the minimum anesthetic concentration of isoflurane in the ball python (Python regius). Vet Anaesth Analg 2019; 46:807-814. [PMID: 31564503 DOI: 10.1016/j.vaa.2019.08.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/30/2019] [Accepted: 08/11/2019] [Indexed: 12/26/2022]
Abstract
OBJECTIVE To evaluate the effects of midazolam and nitrous oxide (N2O) on the minimum anesthetic concentration of isoflurane (MACISO) in ball pythons. STUDY DESIGN Prospective, crossover, randomized, semi-blinded study. ANIMALS A total of nine healthy adult female ball pythons (Python regius) weighing 2.76 ± 0.73 kg. METHODS In each snake, three protocols were evaluated with 2 week washouts: treatment MID-O2, midazolam (1 mg kg-1) administered intramuscularly (IM) and anesthesia induced with isoflurane-oxygen; treatment SAL-O2, saline (0.2 mL kg-1) IM and anesthesia with isoflurane-oxygen; and treatment SAL-N2O, saline IM and anesthesia with isoflurane and 50% nitrous oxide (N2O):50% oxygen. In each treatment, isoflurane was administered by face mask immediately after premedication. Snakes were endotracheally intubated and inspired and end-tidal isoflurane concentrations were monitored. The study design followed a standard bracketing technique, and the MACISO was determined using logistic regression. Electrical stimulation using a Grass stimulator connected to the base of the tail (50 V, 50 Hz, 6.5 ms pulse-1) was used as the supramaximal stimulus. Blood-gas analysis was performed on cardiac blood collected immediately following intubation and after the last stimulation. Blood-gas variables were compared over time and between treatments using linear mixed models. RESULTS MACISO at a body temperature of 30.1 ± 0.4 °C was 1.11% (95% confidence interval, 0.94-1.28%) in SAL-O2 and was significantly decreased to 0.48% (0.29-0.67%) in MID-O2 (p < 0.001) and to 0.92% (0.74-1.09%) in SAL-N2O (p = 0.016). PO2 was significantly lower in MID-O2 and SAL-N2O than in SAL-O2. CONCLUSIONS AND CLINICAL RELEVANCE Midazolam significantly decreased the MACISO by 57% in ball pythons, whereas addition of N2O resulted in a modest, although significant, decrease (17%). MACISO in ball pythons was lower than those previously reported in reptiles.
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Affiliation(s)
- Cédric B Larouche
- Toronto Zoo, Scarborough, ON, Canada; Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
| | - Craig Mosley
- VCA Canada, 404 Veterinary Emergency and Referral Hospital, Newmarket, ON, Canada
| | - Hugues Beaufrère
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
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Kirby AR, Smith B, Crossley DA. Regulation of blood flow in the pulmonary and systemic circuits during submerged swimming in common snapping turtle ( Chelydra serpentina). ACTA ACUST UNITED AC 2019; 222:jeb.205211. [PMID: 31331940 DOI: 10.1242/jeb.205211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 07/18/2019] [Indexed: 11/20/2022]
Abstract
Blood flow patterns and heart rate have rarely been investigated in freely swimming turtles and their regulation during swimming is unknown. In this study, we investigated the blood flow patterns and heart rate in surfacing and during graded, submerged swimming activity in common snapping turtles. We further investigated the effects of beta-adrenergic and cholinergic receptor blockade on blood flow and heart rate during these activities. Our findings illustrate that surfacing is accompanied by an increase in heart rate that is primarily due to beta-adrenergic stimulation. During swimming, this mechanism also increases heart rate while vagal withdrawal facilitates a systemic to pulmonary (left to right) shunt. The results indicate there may be important taxonomic effects on the responses of cardiac function to activity in turtle species.
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Affiliation(s)
- Amanda Reynolds Kirby
- Developmental and Integrative Biology Division, Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
| | - Brandt Smith
- Developmental and Integrative Biology Division, Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
| | - Dane A Crossley
- Developmental and Integrative Biology Division, Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
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Campos R, Justo AFO, Jacintho FF, Mónica FZ, Rojas-Moscoso JA, Moreno RA, Napolitano M, Cogo JC, De Nucci G. Pharmacological and transcriptomic characterization of the nitric oxide pathway in aortic rings isolated from the tortoise Chelonoidis carbonaria. Comp Biochem Physiol C Toxicol Pharmacol 2019; 222:82-89. [PMID: 31028932 DOI: 10.1016/j.cbpc.2019.04.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 04/22/2019] [Accepted: 04/23/2019] [Indexed: 11/29/2022]
Abstract
In this study the nitric oxide (NO)-soluble guanylate cyclase (sGC) and phosphodiesterase-5 (PDE-5) pathway was characterized in tortoise Chelonoidis carbonaria aorta. Concentration response curves (CCR) to ATP, ADP, AMP, adenosine and histamine were performed in the presence and absence of L-NAME in aorta pre-contracted with ACh (3 μM). CCR to SNP, BAY 41-2272 (sGC stimulator), BAY 60-2770 (sGC activator) and tadalafil (PDE-5 inhibitor) were constructed in the presence and absence of ODQ (10 μM). ATP (pEC50 6.1 ± 0.1), ADP (pEC50 6.0 ± 0.2), AMP (pEC50 6.8 ± 0.1) and histamine (pEC50 6.8 ± 0.12) relaxed Chelonoidis aorta and the addition of L-NAME reduced their efficacy (p < .05). Adenosine effects (pEC50 6.6 ± 0.1) were not changed in the presence of L-NAME. SNP (pEC50 7.5 ± 0.7; Emax 102.2 ± 2.5%), BAY 41-2272 (pEC50 7.3 ± 0.2; Emax 130.3 ± 10.2%), BAY 60-2770 (pEC50 11.4 ± 0.1; Emax 130.3 ± 6.5%) and tadalafil (pEC50 6.7 ± 0.3; Emax 121.3 ± 15.3%) relaxed Chelonoidis aorta. The addition of ODQ reduced the SNP and tadalafil maximum response (p < .05) and promoted 63 fold right shift on BAY 41-2272 curve. In contrast, no alteration was observed on BAY 60-2770 response. Transcriptomic analysis for eNOS and sGC were found in aorta and brain libraries with high homology when compared with human transcripts. The NO-sGC-PDE-5 is functionally present in Chelonoidis aorta with a functional and genomic similarity to mammalian vessels. Unlike most of mammalian vessels, ACh did not cause endothelium-dependent relaxation in Chelonoidis carbonaria aortic rings.
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Affiliation(s)
- Rafael Campos
- Superior Institute of Biomedical Sciences, Ceará State University (UECE), Fortaleza, Brazil; Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil.
| | | | - Felipe Fernandes Jacintho
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | - Fabiola Z Mónica
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | | | - Ronilson Agnaldo Moreno
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | - Mauro Napolitano
- Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, Brazil
| | - José Carlos Cogo
- Faculty of Biomedical Engineering, Brazil University, Itaquera, Brazil
| | - Gilberto De Nucci
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil; Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, Brazil
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