Endothelin-1 causes systemic vasodilatation in anaesthetised turtles(<i>Trachemys scripta</i>) through activation of ETB-receptors

Skovgaard, Nini; Warren, Daniel E.; Jackson, Donald C.; Wang, Tobias

doi:10.1242/jeb.01834

Cited by 14 publications

(9 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Resistance in the pulmonary artery is under strong autonomic control, whereby parasympathetic innervation provides a means for pulmonary vasoconstriction, whereas sympathetic innervation and circulating catecholamines result in vasodilatation (Milsom et al, 1977, Lillywhite andDonald, 1989;Comeau and Hicks, 1994;Hicks and Comeau, 1994;Galli et al, 2007). The systemic and pulmonary resistances are further influenced by a suite of nonadrenergic non-cholinergic (NANC) factors (Skovgaard and Wang, 2006;Burggren et al, 2014), such as adenosine (Joyce and Wang, 2014), endothelin (Skovgaard et al, 2005a) and nitric oxide (Crossley et al, 2000;Skovgaard et al, 2005b) with resulting influences on cardiac shunting patterns.…”

Section: Mechanistic Considerationsmentioning

confidence: 99%

In situcardiac perfusion reveals interspecific variation of intraventricular flow separation in reptiles

Joyce

Axelsson

Altimiras

et al. 2016

Journal of Experimental Biology

Self Cite

View full text Add to dashboard Cite

The ventricles of non-crocodilian reptiles are incompletely divided and provide an opportunity for mixing of oxygen-poor blood and oxygen-rich blood (intracardiac shunting). However, both cardiac morphology and in vivo shunting patterns exhibit considerable interspecific variation within reptiles. In the present study, we develop an in situ double-perfused heart approach to characterise the propensity and capacity for shunting in five reptile species: the turtle Trachemys scripta, the rock python Python sebae, the yellow anaconda Eunectes notaeus, the varanid lizard Varanus exanthematicus and the bearded dragon Pogona vitticeps. To simulate changes in vascular bed resistance, pulmonary and systemic afterloads were independently manipulated and changes in blood flow distribution amongst the central outflow tracts were monitored. As previously demonstrated in Burmese pythons, rock pythons and varanid lizards exhibited pronounced intraventricular flow separation. As pulmonary or systemic afterload was raised, flow in the respective circulation decreased. However, flow in the other circulation, where afterload was constant, remained stable. This correlates with the convergent evolution of intraventricular pressure separation and the large intraventricular muscular ridge, which compartmentalises the ventricle, in these species. Conversely, in the three other species, the pulmonary and systemic flows were strongly mutually dependent, such that the decrease in pulmonary flow in response to elevated pulmonary afterload resulted in redistribution of perfusate to the systemic circuit (and vice versa). Thus, in these species, the muscular ridge appeared labile and blood could readily transverse the intraventricular cava. We conclude that relatively minor structural differences between non-crocodilian reptiles result in the fundamental changes in cardiac function. Further, our study emphasises that functionally similar intracardiac flow separation evolved independently in lizards (varanids) and snakes ( pythons) from an ancestor endowed with the capacity for large intracardiac shunts.

show abstract

Section: Mechanistic Considerationsmentioning

confidence: 99%

In situcardiac perfusion reveals interspecific variation of intraventricular flow separation in reptiles

Joyce

Axelsson

Altimiras

et al. 2016

Journal of Experimental Biology

Self Cite

View full text Add to dashboard Cite

show abstract

“…While systemic blood pressure (P sys ) also decreases during anoxia, the reduction in Q sys is considerably larger, indicating a substantial (3-to 5-fold) increase in systemic peripheral resistance (R sys ). At high temperatures, the rise in R sys is largely due to increased ␣-adrenergic tone (54,65), but autonomic control is blunted at low temperature (24) and neither ␣-adrenergic tone (65), adenosine (66), or endothelin-1 (62) contribute to the rise in R sys . Thus, the basis of the augmented R sys during anoxia at low temperature remains unidentified.…”

mentioning

confidence: 99%

Vasoactivity of hydrogen sulfide in normoxic and anoxic turtles (Trachemys scripta)

Stecyk

Skovgaard

Nilsson

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

Self Cite

View full text Add to dashboard Cite

of hydrogen sulfide in normoxic and anoxic turtles (Trachemys scripta). Am J Physiol Regul Integr Comp Physiol 298: R1225-R1239, 2010. First published February 17, 2010 doi:10.1152/ajpregu.00521.2009.-Systemic vascular resistance (Rsys) of freshwater turtles increases substantially during anoxia, but the underlying mechanisms are not fully understood. We investigated whether hydrogen sulfide (H2S), an endogenously produced metabolite believed to be an O 2 sensor/ transducer of vasomotor tone, contributes to the increased R sys of anoxic red-eared slider turtles (Trachemys scripta). Vascular infusion of the H 2S donor NaHS in anesthetized turtles at 21°C and fully recovered normoxic turtles at 5°C and 21°C revealed H 2S to be a potent vasoconstrictor of the systemic circulation. Likewise, wire myography of isolated turtle mesenteric and pulmonary arteries demonstrated H 2S to mediate an anoxia-induced constriction. Intriguingly, however, NaHS did not exert vasoconstrictory effects during anoxia (6 h at 21°C; 14 days at 5°C) when plasma H 2S concentration, estimated from the colorimetric measurement of plasma acid-labile sulfide concentration, likely increased by ϳ3-and 4-fold during anoxia at 21°C, and 5°C, respectively. Yet, blockade of endogenous H 2S production by DL-propargylglycine or hydroxylamine (0.44 mmol/kg) partially reversed the decreased systemic conductance (G sys) exhibited by 5°C anoxic turtles. These findings suggest that the signal transduction pathway of H 2S-mediated vasoactivity is either maximally activated in the systemic circulation of anoxic turtles and/or that it is oxygen dependent. red-eared slider; anoxia; temperature; cardiovascular; systemic resistance; pulmonary resistance; blood pressure; heart NORTH AMERICAN FRESHWATER turtles of the genera Trachemys, Chrysemys, and Chelydra exhibit a remarkable ability to survive a prolonged lack of oxygen (anoxia). At high temperatures (20 -25°C), these turtles successfully recover after 24 h of anoxia, but they can survive weeks to months without oxygen at the low temperatures, at which these animals overwinter (3-5°C) (57, 71). The exceptional anoxia tolerance is achieved through a profound reduction of whole animal metabolic rate, which slows metabolic fuel use and the rate of waste accumulation (21, 30) and the ability to use bone and shell as buffers to ameliorate the catastrophic acidosis that otherwise would accompany the sustained anaerobic metabolism (29,53).The large reduction in metabolism is attended by a pronounced lowering of cardiovascular performance during anoxia, where heart rate (f H ) and systemic blood flow (Q sys ) are drastically reduced and where pulmonary blood flow (Q pul ) virtually ceases (16,23,25,(65)(66)(67). While systemic blood pressure (P sys ) also decreases during anoxia, the reduction in Q sys is considerably larger, indicating a substantial (3-to 5-fold) increase in systemic peripheral resistance (R sys ). At high temperatures, the rise in R sys is largely due to increased ␣-adrenergic tone (54, 65), but ...

show abstract

“…Within reptiles, the role of the ET-receptors has been addressed in only a few studies; in turtles the systemic dilation is mediated through ET B -receptors (Skovgaard et al, 2005b), and in snakes stimulation of ET A -receptors causes a constriction of the aorta (Borgheresi et al, 2006). The amino acid sequence of alligator ET-1 is identical to that of mammals (Platzack et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

“…ET-1 also exerts cardiovascular responses in ectothermic vertebrates (e.g. Olson et al, 1991;Poder et al, 1991;Wang et al, 1999;Hoagland et al, 2000;Platzack et al, 2002;Skovgaard et al, 2005b). In turtles and alligators, injections of ET-1 cause an initial and very pronounced dilation of the systemic vasculature which, in alligators, is followed by constriction.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Hypoxia-induced vasoconstriction in alligator (Alligator mississippiensis) intrapulmonary arteries: a role for endothelin-1?

Skovgaard

Zibrandtsen

Laursen

et al. 2008

Journal of Experimental Biology

Self Cite

View full text Add to dashboard Cite

SUMMARYHypoxic pulmonary vasoconstriction (HPV) is an adaptive response that diverts pulmonary blood flow from poorly ventilated and hypoxic areas of the lung to better ventilated parts, matching blood perfusion to ventilation. HPV is an ancient and highly conserved response expressed in the respiratory organs of all vertebrates. However, the underlying mechanism and the role of the endothelium remain elusive. Isolated intrapulmonary arteries (internal diameter <346·μm) from the American alligator Alligator mississippiensis were mounted in microvascular myographs for isometric tension recording. Resting vessels and vessels contracted with either serotonin (5-HT) or endothelin-1 (ET-1) were exposed to sustained (45·min) hypoxia (P O 2<5·mmHg). In ET-1-contracted vessels, hypoxia induced a monophasic, sustained and fully reversible constriction, which was independent of the endothelium. In relaxed or in 5-HT-contracted vessels, hypoxia did not cause constriction. The effects of ET-1, ET A and ET B as well as the general ET-receptor antagonist were studied. ET-1 caused a contraction of the pulmonary arteries through stimulation of ET A -receptors. ET A and ET B immunoreactive staining revealed the location of both receptors in the smooth muscle layer and of ET B receptors in the endothelium. In conclusion, because precontraction with serotonin did not facilitate HPV, the required precontraction in alligators seems specific to ET-1, which implies that ET-1 plays an important permissive role for the HPV response in alligators.

show abstract

Endothelin-1 causes systemic vasodilatation in anaesthetised turtles(Trachemys scripta) through activation of ETB-receptors

Cited by 14 publications

References 37 publications

In situcardiac perfusion reveals interspecific variation of intraventricular flow separation in reptiles

In situcardiac perfusion reveals interspecific variation of intraventricular flow separation in reptiles

Vasoactivity of hydrogen sulfide in normoxic and anoxic turtles (Trachemys scripta)

Hypoxia-induced vasoconstriction in alligator (Alligator mississippiensis) intrapulmonary arteries: a role for endothelin-1?

Contact Info

Product

Resources

About