Research Article| Volume 49, ISSUE 3, P179-188, November 15, 2004

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Tibolone and its metabolites acutely relax rabbit coronary arteries in vitro


      Objectives: To compare the acute effects of estradiol, tibolone and its metabolites on coronary arteries in vitro and to investigate possible vascular mechanisms. Methods: Coronary artery ring segments from female rabbits were mounted in myographs for isometric tension recordings. Concentration–response curves to tibolone, 3α-OH-tibolone, 3β-OH-tibolone, Δ4-isomer and 17β-estradiol were obtained after precontraction with potassium 30 mmol/l and after addition of -nitro-l-arginine methyl ester 10−4 mol/l (l-NAME, an inhibitor of endothelial nitric oxide (NO) synthase) or tetraethylammonium chloride 10−2 mol/l (TEA, an unspecific inhibitor of potassium channels). The effects of the different substances to calcium concentration–response curves were evaluated. Responses are expressed as maximal contraction (Emax), concentration giving half maximal contraction (log EC50) or area under curve (AUC). Results: Tibolone and its metabolites induced a concentration-dependent vasodilatation comparable to that of 17β-estradiol with the rank of potency: 3β-OH-tibolone ≅ tibolone > 3α-OH-tibolone > Δ4-isomer (ANOVA). l-NAME partly inhibited the relaxation to all substances. TEA induced a slight rightward shift of the relaxation to 3α-OH-tibolone (log EC50: −5.05 versus −5.20; P<0.05; Student’s t-test), but not to the other substances. Calcium concentration-dependent contraction curves were inhibited by all substances compared to controls (AUC, P<0.05, ANOVA). Conclusions: Our data indicate that the acute relaxation induced by tibolone and its metabolites in coronary arteries in vitro are probably mediated by endothelium independent inhibition of calcium channels but may also involve an endothelium-dependent mechanism via nitric oxide. The effect of tibolone is comparable to that of 17β-estradiol in this set-up.


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        • Grady D.
        • Herrington D.
        • Bittner V.
        • Blumenthal R.
        • Davidson M.
        • Hlatky M.
        • et al.
        Cardiovascular disease outcomes during 6.8 years of hormone therapy: heart and estrogen/progestin replacement study follow-up (HERS II).
        J Am Med Assoc. 2002; 288: 49-57
      1. Writing Group for the Women’s Health Initiative Investigators. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the Women’s Health Initiative randomized controlled trial. J Am Med Assoc 2002;288 (3):321–33.

        • Albertazzi P.
        • Di Micco R.
        • Zanardi E.
        Tibolone: a review.
        Maturitas. 1998; 30: 295-305
        • Bjarnason N.H.
        • Bjarnason K.
        • Haarbo J.
        • Rosenquist C.
        • Christiansen C.
        Tibolone: prevention of bone loss in late postmenopausal women.
        J Clin Endocrinol Metab. 1996; 81: 2419-2422
        • Godsland I.F.
        Effects of postmenopausal hormone replacement therapy on lipid, lipoprotein, and apolipoprotein (a) concentrations: analysis of studies published from 1974–2000.
        Fertil Steril. 2001; 75: 898-915
        • Bjarnason N.H.
        • Bjarnason K.
        • Haarbo J.
        • Bennink H.J.
        • Christiansen C.
        Tibolone: influence on markers of cardiovascular disease.
        J Clin Endocrinol Metab. 1997; 82: 1752-1756
        • Zandberg P.
        • Peters J.L.
        • Demacker P.N.
        • Smit M.J.
        • de Reeder E.G.
        • Meuleman D.G.
        Tibolone prevents atherosclerotic lesion formation in cholesterol-fed, ovariectomized rabbits.
        Arterioscler Thromb Vasc Biol. 1998; 18: 1844-1854
        • Clarkson T.B.
        • Anthony M.S.
        • Wagner J.D.
        A comparison of tibolone and conjugated equine estrogens effects on coronary artery atherosclerosis and bone density of postmenopausal monkeys.
        J Clin Endocrinol Metab. 2001; 86: 5396-5404
        • Rosano G.M.
        • Sarrel P.M.
        • Poole-Wilson P.A.
        • Collins P.
        Beneficial effect of oestrogen on exercise-induced myocardial ischaemia in women with coronary artery disease.
        Lancet. 1993; 342: 133-136
        • Webb C.M.
        • Rosano G.M.
        • Collins P.
        Oestrogen improves exercise-induced myocardial ischaemia in women.
        Lancet. 1998; 351: 1556-1557
        • Lloyd G.W.
        • Patel N.R.
        • McGing E.A.
        • Cooper A.F.
        • Kamalvand K.
        • Jackson G.
        Acute effects of hormone replacement with tibolone on myocardial ischaemia in women with angina.
        Int J Clin Pract. 1998; 52: 155-157
        • Lieberman E.H.
        • Gerhard M.D.
        • Uehata A.
        • Walsh B.W.
        • Selwyn A.P.
        • Ganz P.
        • et al.
        Estrogen improves endothelium-dependent, flow-mediated vasodilation in postmenopausal women.
        Ann Intern Med. 1994; 121: 936-941
        • Herrington D.M.
        • Braden G.A.
        • Williams J.K.
        • Morgan T.M.
        Endothelial-dependent coronary vasomotor responsiveness in postmenopausal women with and without estrogen replacement therapy.
        Am J Cardiol. 1994; 73: 951-952
        • Weiner C.P.
        • Lizasoain I.
        • Baylis S.A.
        • Knowles R.G.
        • Charles I.G.
        • Moncada S.
        Induction of calcium-dependent nitric oxide synthases by sex hormones.
        Proc Natl Acad Sci USA. 1994; 91: 5212-5216
        • Jiang C.W.
        • Sarrel P.M.
        • Lindsay D.C.
        • Poole-Wilson P.A.
        • Collins P.
        Endothelium-independent relaxation of rabbit coronary artery by 17 beta-oestradiol in vitro.
        Br J Pharmacol. 1991; 104: 1033-1037
        • Chester A.H.
        • Jiang C.
        • Borland J.A.
        • Yacoub M.H.
        • Collins P.
        Oestrogen relaxes human epicardial coronary arteries through non-endothelium-dependent mechanisms.
        Coron Artery Dis. 1995; 6: 417-422
        • Kitazawa T.
        • Hamada E.
        • Kitazawa K.
        • Gaznabi A.K.
        Non-genomic mechanism of 17 beta-oestradiol-induced inhibition of contraction in mammalian vascular smooth muscle.
        J Physiol. 1997; 499: 497-511
        • White R.E.
        • Darkow D.J.
        • Lang J.L.
        Estrogen relaxes coronary arteries by opening BKCa channels through a cGMP-dependent mechanism.
        Circ Res. 1995; 77: 936-942
        • Ma L.
        • Robinson C.P.
        • Thadani U.
        • Patterson E.
        Effect of 17-beta estradiol in the rabbit: endothelium-dependent and -independent mechanisms of vascular relaxation.
        J Cardiovasc Pharmacol. 1997; 30: 130-135
        • Otter D.
        • Austin C.
        Effects of 17beta-oestradiol on rat isolated coronary and mesenteric artery tone: involvement of nitric oxide.
        J Pharm Pharmacol. 1998; 50: 531-538
        • Bucci M.
        • Roviezzo F.
        • Cicala C.
        • Pinto A.
        • Cirino G.
        17-Beta-oestradiol-induced vasorelaxation in vitro is mediated by eNOS through hsp90 and akt/pkb dependent mechanism.
        Br J Pharmacol. 2002; 135: 1695-1700
        • Williams J.K.
        • Hall J.
        • Anthony M.S.
        • Register T.C.
        • Reis S.E.
        • Clarkson T.B.
        A comparison of tibolone and hormone replacement therapy on coronary artery and myocardial function in ovariectomized atherosclerotic monkeys.
        Menopause. 2002; 9: 41-51
        • de Kleijn M.J.
        • Wilmink H.W.
        • Bots M.L.
        • Bak A.A.
        • van der Schouw Y.T.
        • Planellas J.
        • et al.
        Hormone replacement therapy and endothelial function. Results of a randomized controlled trial in healthy postmenopausal women.
        Atherosclerosis. 2001; 159: 357-365
        • Mulvany M.J.
        • Halpern W.
        Contractile properties of small arterial resistance vessels in spontaneously hypertensive and normotensive rats.
        Circ Res. 1977; 41: 19-26
        • Caulin-Glaser T.
        • Garcia-Cardena G.
        • Sarrel P.
        • Sessa W.C.
        • Bender J.R.
        17 beta-estradiol regulation of human endothelial cell basal nitric oxide release, independent of cytosolic Ca2+ mobilization.
        Circ Res. 1997; 81: 885-892
        • Chen Z.
        • Yuhanna I.S.
        • Galcheva-Gargova Z.
        • Karas R.H.
        • Mendelsohn M.E.
        • Shaul P.W.
        Estrogen receptor alpha mediates the nongenomic activation of endothelial nitric oxide synthase by estrogen.
        J Clin Invest. 1999; 103: 401-406
        • Haynes M.P.
        • Sinha D.
        • Russell K.S.
        • Collinge M.
        • Fulton D.
        • Morales-Ruiz M.
        • et al.
        Membrane estrogen receptor engagement activates endothelial nitric oxide synthase via the PI3-kinase-Akt pathway in human endothelial cells.
        Circ Res. 2000; 87: 677-682
        • Wyckoff M.H.
        • Chambliss K.L.
        • Mineo C.
        • Yuhanna I.S.
        • Mendelsohn M.E.
        • Mumby S.M.
        • et al.
        Plasma membrane estrogen receptors are coupled to endothelial nitric-oxide synthase through Galpha(i).
        J Biol Chem. 2001; 276: 27071-27076
        • Chambliss K.L.
        • Yuhanna I.S.
        • Anderson R.G.
        • Mendelsohn M.E.
        • Shaul P.W.
        ERbeta has nongenomic action in caveolae.
        Mol Endocrinol. 2002; 16: 938-946
        • Figtree G.A.
        • Lu Y.
        • Webb C.M.
        • Collins P.
        Raloxifene acutely relaxes rabbit coronary arteries in vitro by an estrogen receptor-dependent and nitric oxide-dependent mechanism.
        Circulation. 1999; 100: 1095-1101
        • Zoma W.
        • Baker R.S.
        • Lang U.
        • Clark K.E.
        Hemodynamic response to tibolone in reproductive and nonreproductive tissues in the sheep.
        Am J Obstet Gynecol. 2001; 184: 544-551
        • de Gooyer M.E.
        • Deckers G.H.
        • Schoonen W.G.
        • Verheul H.A.
        • Kloosterboer H.J.
        Receptor profiling and endocrine interactions of tibolone.
        Steroids. 2003; 68: 21-30
        • Figtree G.A.
        • McDonald D.
        • Watkins H.
        • Channon K.M.
        Truncated estrogen receptor alpha 46-kDa isoform in human endothelial cells: relationship to acute activation of nitric oxide synthase.
        Circulation. 2003; 107: 120-126
        • Murphy J.G.
        • Khalil R.A.
        Decreased [Ca(2+)](i) during inhibition of coronary smooth muscle contraction by 17beta-estradiol, progesterone, and testosterone.
        J Pharmacol Exp Ther. 1999; 291: 44-52
        • Song J.
        • Standley P.R.
        • Zhang F.
        • Joshi D.
        • Gappy S.
        • Sowers J.R.
        • et al.
        Tamoxifen (estrogen antagonist) inhibits voltage-gated calcium current and contractility in vascular smooth muscle from rats.
        J Pharmacol Exp Ther. 1996; 277: 1444-1453
        • Standen N.B.
        • Quayle J.M.
        K+ channel modulation in arterial smooth muscle.
        Acta Physiol Scand. 1998; 164: 549-557
        • Dalsgaard T.
        • Larsen C.R.
        • Mortensen A.
        • Larsen J.J.
        • Ottesen B.
        New animal model for the study of postmenopausal coronary and cerebral artery function: the Watanabe heritable hyperlipidemic rabbit fed on a diet avoiding phytoestrogens.
        Climacteric. 2002; 5: 178-189
        • Kloosterboer H.J.
        Tibolone: a steroid with a tissue-specific mode of action.
        J Steroid Biochem Mol Biol. 2001; 76: 231-238