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Filgueira FP, Lobato NS, Nascimento DL, Ceravolo GS, Giachini FRC, Lima VV, Dantas AP, Fortes ZB, Webb RC, Tostes RC, Carvalho MHC. Equilin displays similar endothelium-independent vasodilator potential to 17β-estradiol regardless of lower potential to inhibit calcium entry. Steroids 2019; 141:46-54. [PMID: 30458188 PMCID: PMC6984400 DOI: 10.1016/j.steroids.2018.11.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 10/21/2018] [Accepted: 11/14/2018] [Indexed: 12/24/2022]
Abstract
Conjugated equine estrogens (CEE) have been widely used by women who seek to relieve symptoms of menopause. Despite evidence describing protective effects against risk factors for cardiovascular diseases by naturally occurring estrogens, little is known about the vascular effects of equilin, one of the main components of CEE and not physiologically present in women. In this regard, the present study aims to compare the vascular effects of equilin in an experimental model of hypertension with those induced by 17β-estradiol. Resistance mesenteric arteries from female spontaneously hypertensive rats (SHR) were used for recording isometric tension in a small vessel myograph. As effectively as 17β-estradiol, equilin evoked a concentration-dependent relaxation in mesenteric arteries from female SHRs contracted with KCl, U46619, PDBu or ET-1. Equilin-induced vasodilation does not involve classical estrogen receptor activation, since the estrogen receptor antagonist (ICI 182,780) failed to inhibit relaxation in U46619-precontracted mesenteric arteries. Vasorelaxation was not affected by either endothelium removal or by inhibiting the release or action of endothelium-derived factors. Incubation with L-NAME (NOS inhibitor), ODQ (guanylyl cyclase inhibitor) or KT5823 (inhibitor of protein kinase G) did not affect equilin-induced relaxation. Similarly, indomethacin (COX inhibitor) or blockage of potassium channels with tetraethylammonium, glibenclamide, 4-aminopyridine, or ouabain did not affect equilin-induced relaxation. Inhibitors of adenylyl cyclase SQ22536 or protein kinase A (KT5720) also had no effects on equilin-induced relaxation. While 17β-estradiol inhibited calcium (Ca2+) -induced contractions in high-K+ depolarization medium in a concentration-dependent manner, equilin induced a slight rightward-shift in the contractile responses to Ca2+. Comparable pattern of responses were observed in the concentration-response curves to (S)-(-)-Bay K 8644, a L-type Ca2+ channel activator. Equilin was unable to block the transitory contraction produced by caffeine-induced Ca2+ release from intracellular stores. In conclusion, equilin blocks L-type Ca2+ channels less effectively than 17β-estradiol. Despite its lower effectiveness, equilin equally relaxes resistance mesenteric arteries by blocking Ca2+ entry on smooth muscle.
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Affiliation(s)
- Fernando P Filgueira
- Department of Pharmacology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil; Department of Physiology, Augusta University, Augusta, GA, USA; Faculty of Medicine, Institute of Health Sciences, Federal University of Jatai, Jatai, GO, Brazil.
| | - Núbia S Lobato
- Department of Pharmacology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil; Department of Physiology, Augusta University, Augusta, GA, USA; Faculty of Medicine, Institute of Health Sciences, Federal University of Jatai, Jatai, GO, Brazil
| | - Denise L Nascimento
- Faculty of Medicine, Institute of Health Sciences, Federal University of Jatai, Jatai, GO, Brazil
| | - Graziela S Ceravolo
- Department of Pharmacology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil; Department of Physiological Sciences, Biological Sciences Center, State University of Londrina, Londrina, PR, Brazil
| | - Fernanda R C Giachini
- Department of Physiology, Augusta University, Augusta, GA, USA; Institute of Biological and Health Sciences, Federal University of Mato Grosso, Barra do Garças, MT, Brazil
| | - Victor V Lima
- Department of Physiology, Augusta University, Augusta, GA, USA; Institute of Biological and Health Sciences, Federal University of Mato Grosso, Barra do Garças, MT, Brazil; Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | - Ana Paula Dantas
- Experimental Cardiology, Institut Clínic Cardiovascular, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Zuleica B Fortes
- Department of Pharmacology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil
| | - R Clinton Webb
- Department of Physiology, Augusta University, Augusta, GA, USA
| | - Rita C Tostes
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | - Maria Helena C Carvalho
- Department of Pharmacology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil
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Jorge Neto SD, Machado JSR, Palei ACT, Martins WP, Sandrim VC, Araujo Júnior E, Amaral LM, Tanus-Santos JE, Duarte G, Cavalli RC. Assessment of nitrite oxide and maternal-fetal Doppler parameters during pregnancy. J Matern Fetal Neonatal Med 2015; 29:3406-9. [PMID: 26653276 DOI: 10.3109/14767058.2015.1130817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The objective was to evaluate and compare the whole blood nitrite concentration in the three trimesters of pregnancy. Additionally, we investigate whether there is any relation between nitrite concentrations and Doppler ultrasound analysis of some maternal and fetal vessels. METHODS Thirty-three healthy pregnant women were examined at the first (11-14 weeks), second (20-24 weeks) and third trimester (34-36 weeks) of pregnancy. In the three exams, we determined the maternal whole blood nitrite concentration and uterine arteries Doppler analysis to determine pulsatility index (PI), and resistance index (RI). In the second and third trimester we also performed fetal umbilical and middle cerebral arteries PI and RI. We compared the concentrations of nitrite in three trimesters and correlated with Doppler parameters. RESULTS No difference was observed in the whole blood nitrite concentrations across trimesters: 151.70 ± 77.90 nmol/ml, 142.10 ± 73.50 nmol/ml and 147.10 ± 87.30 nmol/ml; first, second and third trimesters, respectively. We found no difference in correlation between whole blood nitrite concentration and Doppler parameters from the evaluated vessels. CONCLUSIONS In healthy pregnant women, the nitrite concentrations did not change across gestational trimesters and there was also no strong correlation with Doppler impedance indices from maternal uterine arteries and fetal umbilical and middle cerebral arteries.
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Affiliation(s)
- Salim Demétrio Jorge Neto
- a Department of Obstetrics and Gynecology , Ribeirao Preto Medical School, University of Sao Paulo (FMRP-USP) , Ribeirão Preto - SP , Brazil
| | - Jackeline Souza Rangel Machado
- a Department of Obstetrics and Gynecology , Ribeirao Preto Medical School, University of Sao Paulo (FMRP-USP) , Ribeirão Preto - SP , Brazil
| | - Ana Carolina Tavares Palei
- b Departament of Physiology and Biophysics , University of Mississipi Medical Center , Jackson , MS , USA
| | - Wellington Paula Martins
- a Department of Obstetrics and Gynecology , Ribeirao Preto Medical School, University of Sao Paulo (FMRP-USP) , Ribeirão Preto - SP , Brazil
| | - Valéria Cristina Sandrim
- c Departament of Pharmacology , Botucatu Medical School, São Paulo State University (UNESP) , Botucatu - SP , Brazil
| | - Edward Araujo Júnior
- d Department of Obstetrics , Paulista School of Medicine, Federal University of São Paulo (EPM-UNIFESP) , São Paulo - SP , Brazil , and
| | - Lorena Machado Amaral
- b Departament of Physiology and Biophysics , University of Mississipi Medical Center , Jackson , MS , USA
| | - José Eduardo Tanus-Santos
- e Departament of Pharmacology , Ribeirão Preto Medical School, University of Sao Paulo (FMRP-USP) , Ribeirão Preto - SP , Brazil
| | - Geraldo Duarte
- a Department of Obstetrics and Gynecology , Ribeirao Preto Medical School, University of Sao Paulo (FMRP-USP) , Ribeirão Preto - SP , Brazil
| | - Ricardo Carvalho Cavalli
- a Department of Obstetrics and Gynecology , Ribeirao Preto Medical School, University of Sao Paulo (FMRP-USP) , Ribeirão Preto - SP , Brazil
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Maher J, Hunter AC, Mabley JG, Lippiat J, Allen MC. Smooth muscle relaxation and activation of the large conductance Ca(++)-activated K+ (BK(Ca)) channel by novel oestrogens. Br J Pharmacol 2015; 169:1153-65. [PMID: 23586466 DOI: 10.1111/bph.12211] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 02/25/2013] [Accepted: 03/24/2013] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Oestrogens can interact directly with membrane receptors and channels and can activate vascular BK(Ca) channels. We hypothesized that novel oestrogen derivatives could relax smooth muscle by an extracllular effect on the α and β1 subunits of the BK(Ca) channel, rather than at an intracellular site. EXPERIMENTAL APPROACH We studied the effects of novel oestrogens on the tension of pre-contracted isolated rat aortic rings, and on the electrophysiological properties of HEK 293 cells expressing the hSloα or hSloα+β1 subunits. Two of the derivatives incorporated a quaternary ammonium side-chain making them membrane impermeable. KEY RESULTS Oestrone, oestrone oxime and Quat DME-oestradiol relaxed pre-contracted rat aorta, but only Quat DME-oestradiol-induced relaxation was iberiotoxin sensitive. However, only potassium currents recorded in HEK 293 cells over-expressing both hSloα and hSloβ1 were activated by oestrone, oestrone oxime and Quat DME-oestradiol. CONCLUSION AND IMPLICATIONS The novel oestrogens were able to relax smooth muscle, but through different mechanisms. In particular, oestrone oxime required the presence of the endothelium to exert much of its effect, whilst Quat DME-oestradiol depended both on NO and BK(Ca) channel activation. The activation of BK(Ca) currents in HEK 293 cells expressing hSloα+β1 by Quat DME-oestradiol is consistent with an extracellular binding site between the two subunits. The binding site resides between the extracellular N terminal of the α subunit and the extracellular loop between TM1 and 2 of the β1 subunit. Membrane-impermeant Quat DME-oestradiol lacks an exchangeable hydrogen on the A ring obviating antioxidant activity.
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Affiliation(s)
- J Maher
- School of Pharmacy and Biomolecular Science, University of Brighton, Brighton, UK
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Miyague AH, Martins WP, Machado JSR, Palei AC, Amaral LM, Teixeira DM, Sandrim VC, Sertorio JTC, Tanus-Santos JE, Duarte G, Cavalli RC. Maternal flow-mediated dilation and nitrite concentration during third trimester of pregnancy and postpartum period. Hypertens Pregnancy 2013; 32:225-34. [PMID: 23782031 DOI: 10.3109/10641955.2013.790412] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVES To compare maternal flow-mediated dilation (FMD) of the brachial artery and nitrite concentration between third trimester of pregnancy (3rdT) and postpartum (PP) period. Additionally, we will evaluate whether FMD correlates with nitrite concentration in both periods. METHODS Eligibility criteria was healthy women with singleton pregnancy, gestational age >28 weeks, nonsmokers, and no personal or family history of vascular disease. Each women was examined during 3rdT and between 8 and 12 weeks PP to evaluate FMD and nitrite concentration in whole blood. Women not examined in both periods were excluded. Values between both periods were compared using paired t tests. Correlation between FMD and nitrite was examined by Pearson correlation coefficient. Significance level set as p < 0.05. RESULTS We invited 42 pregnant women. Among them, 35 were eligible and 7 of them were excluded for not attending the PP evaluation resulting in 28 participants analyzed. We found no significant change in FMD (10.39 ± 5.57% vs. 8.42 ± 4.21%; p = 0.11; 3rdT vs. PP, respectively) and no significant change in nitrite concentration (257.41 ± 122.95 nmol/L vs. 237.16 ± 90.01 nmol/L; p = 0.28). Baseline brachial artery diameter had a significant reduction (3.11 ± 0.30 to 2.75 ± 0.34 mm; p < 0.01). No significant correlation between FMD and nitrite during 3rdT (r = -0.13; p = 0.50) or PP (r = 0.14; p = 0.48) was found. CONCLUSIONS We did not observe significant changes in both FMD and nitrite concentration between third trimester and the PP period. FMD did not correlate with nitrite in both periods. More studies are needed to confirm our findings.
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Affiliation(s)
- Andre H Miyague
- Departamento de Ginecologia e Obstetricia da Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo (FMRP-USP), Ribeirao Preto, Brazil.
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