1. Vasoactivity of hydrogen sulfide in normoxic and anoxic turtles (Trachemys scripta)
- Author
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Stecyk, Jonathan A.W., Skovgaard, Nini, Nilsson, Goran E., and Wang, Tobias
- Subjects
Turtles -- Physiological aspects ,Hydrogen sulfide -- Health aspects ,Biological sciences - Abstract
Systemic vascular resistance ([R.sub.sys]) of freshwater turtles increases substantially during anoxia, but the underlying mechanisms are not fully understood. We investigated whether hydrogen sulfide ([H.sub.2]S), an endogenously produced metabolite believed to be an [O.sub.2] sensor/ transducer of vasomotor tone, contributes to the increased [R.sub.sys] of anoxic red-eared slider turtles (Trachemys scripta). Vascular infusion of the [H.sub.2]S donor Naris in anesthetized turtles at 21[degrees]C and fully recovered normoxic turtles at 5[degrees]C and 21[degrees]C revealed [H.sub.2]S to be a potent vasoconstrictor of the systemic circulation. Likewise, wire myography of isolated turtle mesenteric and pulmonary arteries demonstrated [H.sub.2]S to mediate an anoxia-induced constriction. Intriguingly, however, Naris did not exert vasoconstrictory effects during anoxia (6 h at 21[degrees]C; 14 days at 5[degrees]C) when plasma [H.sub.2]S concentration, estimated from the colorimetric measurement of plasma acid-labile sulfide concentration, likely increased by ~3-and 4-fold during anoxia at 21[degrees]C, and 5[degrees]C, respectively. Yet, blockade of endogenous [H.sub.2]S production by DL-propargylglycine or hydroxylamine (0.44 mmol/kg) partially reversed the decreased systemic conductance ([G.sub.sys]) exhibited by 5[degrees]C anoxic turtles. These findings suggest that the signal transduction pathway of [H.sub.2]S-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 doi: 10.1152/ajpregu.00521.2009.
- Published
- 2010