Vasoactivity of the gasotransmitters hydrogen sulfide and carbon monoxide in the chicken ductus arteriosus

van der Sterren S, Kleikers P, Zimmermann LJI, Villamor E. Vasoactivity of the gasotransmitters hydrogen sulfide and carbon monoxide in the chicken ductus arteriosus. Am J Physiol Regul Integr Comp Physiol 301: R1186-R1198, 2011. First published August 3, 2011; doi: 10.1152/ajpregu.00729.2010.-Besides nitric oxide (NO) and carbon monoxide (CO), hydrogen sulfide (H(2)S) is a third gaseous messenger that may play a role in controlling vascular tone and has been proposed to serve as an O(2) sensor. However, whether H(2)S is vasoactive in the ductus arteriosus (DA) has not yet been studied. We investigated, using wire myography, the mechanical responses induced by Na(2)S (1 mu M-1 mM), which forms H(2)S and HS(-) in solution, and by authentic CO (0.1 mu M-0.1 mM) in DA rings from 19-day chicken embryos. Na(2)S elicited a 100% relaxation (pD(2) 4.02) of 21% O(2)-contracted and a 50.3% relaxation of 62.5 mM KCl-contracted DA rings. Na(2)S-induced relaxation was not affected by presence of the NO synthase inhibitor L-NAME, the soluble guanylate cyclase (sGC) inhibitor ODQ, or the K(+) channel inhibitors tetraethylammonium (TEA; nonselective), 4-aminopyridine (4-AP, K(V)), glibenclamide (K(ATP)), iberiotoxin (BK(Ca)), TRAM-34 (IK(Ca)), and apamin (SK(Ca)). CO also relaxed O(2)-contracted (60.8% relaxation) and KCl-contracted (18.6% relaxation) DA rings. CO-induced relaxation was impaired by ODQ, TEA, and 4-AP (but not by L-NAME, glibenclamide, iberiotoxin, TRAM-34 or apamin), suggesting the involvement of sGC and K(V) channel stimulation. The presence of inhibitors of H(2)S or CO synthesis as well as the H(2)S precursor L-cysteine or the CO precursor hemin did not significantly affect the response of the DA to changes in O(2) tension. Endothelium-dependent and -independent relaxations were also unaffected. In conclusion, our results indicate that the gasotransmitters H(2)S and CO are vasoactive in the chicken DA but they do not suggest an important role for endogenous H(2)S or CO in the control of chicken ductal reactivity

Effects of sex and estrogen on chicken ductus arteriosus reactivity

Flinsenberg TWH, van der Sterren S, van Cleef ANH, Schuurman MJ, Agren P, Villamor E. Effects of sex and estrogen on chicken ductus arteriosus reactivity. Am J Physiol Regul Integr Comp Physiol 298: R1217-R1224, 2010. First published February 17, 2010; doi: 10.1152/ajpregu.00839.2009.-Sex hormones have an important influence on cardiovascular physiology and pathophysiology and sex differences in vascular reactivity have been widely demonstrated. In the present study we hypothesized 1) the presence of sexual dimorphism in chicken ductus arteriosus (DA) responsiveness to contractile and relaxant stimuli and 2) that estrogens are vasoactive in the chicken DA. In vitro contractions (assessed with a wire myograph) induced by normoxia, KCl, 4-aminopyridine, norepinephrine, phenylephrine, U46619, or endothelin-1, as well as relaxations induced by ACh, sodium nitroprusside, BAY 41-2272, PGE2, isoproterenol, forskolin, Y-27632, and hydroxyfasudil were not significantly different between males and females. The estrogen 17 beta-estradiol elicited concentration-dependent relaxation of KCl-, phenylephrine, and oxygen-induced active tone in male and female chicken DA. The stereoisomer 17 alpha-estradiol showed lesser relaxant effects, and the selective estrogen receptor (ER) agonists 4,4',4 ''-(4-propyl-[H-1]pyrazole-1,3,5-triyl)tris-phenol (ER alpha) and 2,3-bis(4-hydroxyphenyl)-propionitrile (ER alpha) did not show any effect. There were no sex differences in the responses to estrogen. Endothelium removal or the presence of the soluble guanylate cyclase inhibitor ODQ, the K+ channel blockers tetraethylammonium, glibenclamide, and charybdotoxin, or the ER antagonist fulvestrant did not modify 17 beta-estradiol-induced relaxation. CaCl2 (30 mu M-10 mM) induced concentration-dependent contraction in DA rings depolarized by 62.5 mM KCl or stimulated with 21% O-2 in Ca2+-free medium. Preincubation with 17 beta-estradiol or the L-type Ca2+ channel blocker nifedipine produced an inhibition of CaCl2-induced contractions. In conclusion, there are no sex-related differences in chicken DA reactivity. The estrogen 17 beta-estradiol induces an endothelium-independent relaxation of chicken DA that is not mediated by ER activation. This relaxant effect is, at least partially, due to inhibition of Ca2+ entry from extracellular space