title: Estrogen receptor subtypes mediate distinct microvascular dilation and reduction in [Ca2+]I in mesenteric microvessels of female rat.
abstract: Estrogen interacts with estrogen receptors (ERs) to induce vasodilation, but the ER subtype and post-ER relaxation pathways are unclear. We tested if ER subtypes mediate distinct vasodilator and intracellular free Ca(2+) concentration ([Ca(2+)]i) responses via specific relaxation pathways in the endothelium and vascular smooth muscle (VSM). Pressurized mesenteric microvessels from female Sprague-Dawley rats were loaded with fura-2, and the changes in diameter and [Ca(2+)]i in response to 17β-estradiol (E2) (all ERs), PPT (4,4',4''-[4-propyl-(1H)-pyrazole-1,3,5-triyl]-tris-phenol) (ERα), diarylpropionitrile (DPN) (ERβ), and G1 [(±)-1-[(3aR*,4S*,9bS*)-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro:3H-cyclopenta(c)quinolin-8-yl]-ethanon] (GPR30) were measured. In microvessels preconstricted with phenylephrine, ER agonists caused relaxation and decrease in [Ca(2+)]i that were with E2 = PPT > DPN > G1, suggesting that E2-induced vasodilation involves ERα > ERβ > GPR30. Acetylcholine caused vasodilation and decreased [Ca(2+)]i, which were abolished by endothelium removal or treatment with the nitric oxide synthase blocker Nω-nitro-l-arginine methyl ester (L-NAME) and the K(+) channel blockers tetraethylammonium (nonspecific) or apamin (small conductance Ca(2+)-activated K(+) channel) plus TRAM-34 (1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole) (intermediate conductance Ca(2+)-activated K(+) channel), suggesting endothelium-derived hyperpolarizing factor-dependent activation of KCa channels. E2-, PPT-, DPN-, and G1-induced vasodilation and decreased [Ca(2+)]i were not blocked by L-NAME, TEA, apamin plus TRAM-34, iberiotoxin (large conductance Ca(2+)- and voltage-activated K(+) channel), 4-aminopyridine (voltage-dependent K(+) channel), glibenclamide (ATP-sensitive K(+) channel), or endothelium removal, suggesting an endothelium- and K(+) channel-independent mechanism. In endothelium-denuded vessels preconstricted with phenylephrine, high KCl, or the Ca(2+) channel activator Bay K 8644 (1,4-dihydro-2,6-dimethyl-5-nitro-4-[2-(trifluoromethyl)phenyl]-3-pyridinecarboxylic acid methyl ester), ER agonist-induced relaxation and decreased [Ca(2+)]i were with E2 = PPT > DPN > G1 and not inhibited by the guanylate cyclase inhibitor ODQ [1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one], and showed a similar relationship between decreased [Ca(2+)]i and vasorelaxation, supporting direct effects on Ca(2+) entry in VSM. Immunohistochemistry revealed ERα, ERβ, and GPR30 mainly in the vessel media and VSM. Thus, in mesenteric microvessels, ER subtypes mediate distinct vasodilation and decreased [Ca(2+)]i (ERα > ERβ > GPR30) through endothelium- and K(+) channel-independent inhibition of Ca(2+) entry mechanisms of VSM contraction.
authors.affiliation: Vascular Surgery Research Laboratory, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Marc Q
authors.initials: MQ
authors.lastname: Mazzuca
authors.affiliation: Vascular Surgery Research Laboratory, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Karina M
authors.initials: KM
authors.lastname: Mata
authors.affiliation: Vascular Surgery Research Laboratory, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Vascular Surgery Research Laboratory, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Sridhar S
authors.initials: SS
authors.lastname: Rangan
authors.affiliation: Vascular Surgery Research Laboratory, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts raouf_khalil@hms.harvard.edu.
authors.forename: Raouf A
authors.initials: RA
authors.lastname: Khalil
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000819:agonists / Q000378:metabolism*; D047629:Estrogen Receptor beta / Q000819:agonists / Q000378:metabolism*; D004967:Estrogens / Q000494:pharmacology*; D004971:Estrus / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D008638:Mesenteric Arteries / Q000187:drug effects / Q000378:metabolism*; D055806:Microvessels / Q000187:drug effects / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D017207:Rats, Sprague-Dawley; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
chemical_list: D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004967:Estrogens; D002118:Calcium