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Buxton ILO, Asif H, Barnett SD. β3 Receptor Signaling in Pregnant Human Myometrium Suggests a Role for β3 Agonists as Tocolytics. Biomolecules 2023; 13:1005. [PMID: 37371585 DOI: 10.3390/biom13061005] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/07/2023] [Accepted: 06/14/2023] [Indexed: 06/29/2023] Open
Abstract
Preterm labor leading to preterm birth is the leading cause of infant morbidity and mortality. At the present time, nothing can reliably halt labor once it begins. The knowledge that agonists of the β2 adrenergic receptor relax airway smooth muscle and are effective in the treatment of asthma led to the notion that β2 mimetics would prevent preterm birth by relaxing uterine smooth muscle. The activation of cAMP-dependent protein kinase by β2 receptors is unable to provide meaningful tocolysis. The failure of β2 agonists such as ritodrine and terbutaline to prevent preterm birth suggests that the regulation of uterine smooth muscle is disparate from that of airway. Other smooth muscle quiescent-mediating molecules, such as nitric oxide, relax vascular smooth muscle in a cGMP-protein kinase G-dependent manner; however, nitric oxide activation of protein kinase G fails to explain the relaxation of the myometrium to nitric oxide. Moreover, nitric oxide-mediated relaxation is blunted in preterm labor, and thus, for this reason and because of the fall in maternal blood pressure, nitric oxide cannot be employed as a tocolytic. The β3 adrenergic receptor-mediated relaxation of the human myometrium is claimed to be cAMP-dependent protein kinase-dependent. This is scientifically displeasing given the failure of β2 agonists as tocolytics and suggests a non-canonical signaling role for β3AR in myometrium. The addition of the β3 agonist mirabegron to pregnant human myometrial strips in the tissue bath relaxes oxytocin-induced contractions. Mirabegron stimulates nitric oxide production in myometrial microvascular endothelial cells, and the relaxation of uterine tissue in vitro is partially blocked by the addition of the endothelial nitric oxide synthase blocker Nω-Nitro-L-arginine. Recent data suggest that both endothelial and smooth muscle cells respond to β3 stimulation and contribute to relaxation through disparate signaling pathways. The repurposing of approved medications such as mirabegron (Mybetriq™) tested in human myometrium as uterine tocolytics can advance the prevention of preterm birth.
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Affiliation(s)
- Iain L O Buxton
- Myometrial Function Group, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Hazik Asif
- Myometrial Function Group, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Scott D Barnett
- Myometrial Function Group, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
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Barnett SD, Asif H, Buxton ILO. Novel identification and modulation of the mechanosensitive Piezo1 channel in human myometrium. J Physiol 2023; 601:1675-1690. [PMID: 35941750 PMCID: PMC9905381 DOI: 10.1113/jp283299] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 06/14/2022] [Indexed: 11/08/2022] Open
Abstract
Approximately 10% of US births deliver preterm before 37 weeks of completed gestation. Premature infants are at risk for life-long debilitating morbidities and death, and spontaneous preterm labour explains 50% of preterm births. In all cases existing treatments are ineffective, and none are FDA approved. The mechanisms that initiate preterm labour are not well understood but may result from dysfunctional regulation of quiescence mechanisms. Human pregnancy is accompanied by large increases in blood flow, and the uterus must enlarge by orders of magnitude to accommodate the growing fetus. This mechanical strain suggests that stretch-activated channels may constitute a mechanism to explain gestational quiescence. Here we identify for the first time that Piezo1, a mechanosensitive cation channel, is present in the uterine smooth muscle and microvascular endothelium of pregnant myometrium. Piezo is downregulated during preterm labour, and stimulation of myometrial Piezo1 in an organ bath with the agonist Yoda1 relaxes the tissue in a dose-dependent fashion. Further, stimulation of Piezo1 while inhibiting protein kinase A, AKT, or endothelial nitric oxide synthase mutes the negative inotropic effects of Piezo1 activation, intimating that actions on the myocyte and endothelial nitric oxide signalling contribute to Piezo1-mediated contractile dynamics. Taken together, these data highlight the importance of stretch-activated channels in pregnancy maintenance and parturition, and identify Piezo1 as a tocolytic target of interest. KEY POINTS: Spontaneous preterm labour is a serious obstetric dilemma without a known cause or effective treatments. Piezo1 is a stretch-activated channel important to muscle contractile dynamics. Piezo1 is present in the myometrium and is dysregulated in women who experience preterm labour. Activation of Piezo1 by the agonist Yoda1 relaxes the myometrium in a dose-dependent fashion, indicating that Piezo1 modulation may have therapeutic benefits to treat preterm labour.
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Affiliation(s)
- Scott D Barnett
- Department of Pharmacology, Center for Molecular Medicine, Reno School of Medicine, University of Nevada, Reno, NV, USA
| | - Hazik Asif
- Department of Pharmacology, Center for Molecular Medicine, Reno School of Medicine, University of Nevada, Reno, NV, USA
| | - Iain L O Buxton
- Department of Pharmacology, Center for Molecular Medicine, Reno School of Medicine, University of Nevada, Reno, NV, USA
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Macêdo CAF, Paiva GOD, Menezes PMN, Ribeiro TF, Brito MC, Vilela DAD, Duarte Filho LAMDS, Ribeiro FPRDA, Lucchese AM, Lima JTD, Silva FS. Lippia origanoides essential oil induces tocolytic effect in virgin rat uterus and inhibits writhing in a dysmenorrhea mouse model. JOURNAL OF ETHNOPHARMACOLOGY 2022; 290:115099. [PMID: 35167934 DOI: 10.1016/j.jep.2022.115099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/25/2022] [Accepted: 02/07/2022] [Indexed: 06/14/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The species Lippia origanoides Kunth, popularly known as "salva-de-marajó", is used in Brazilian traditional "quilombola" communities to treat menstrual cramps and uterine inflammation. AIM OF THE STUDY Evaluate the spasmolytic activity of Lippia origanoides essential oil (LOO) on experimental models of uterine conditions related to menstrual cramps and investigate its mechanism of action. MATERIALS AND METHODS Virgin rat-isolated uterus was mounted in the organ bath apparatus to evaluate the spasmolytic effect of LOO on basal tonus and contractions induced by carbachol, KCl, or oxytocin. We used pharmacological agents to verify the relaxation mechanism of LOO. The evaluation of uterine contractility in virgin rats, after treatment with LOO for three consecutive days, was carried out by the construction of a concentration-response curve with oxytocin or carbachol. The primary dysmenorrhea animal model was replicated with an injection of estradiol cypionate in female mice for three consecutive days, followed by intraperitoneal application of oxytocin. RESULTS LOO relaxed the rat uterus precontracted with 10-2 IU/mL oxytocin (logEC50 = 1.98 ± 0.07), 1 μM carbachol (logEC50 = 1.42 ± 0.07) or 60 mM KCl (logEC50 = 1.53 ± 0.05). It was also able relax uterus on spontaneous contractions (logEC50 = 0.41 ± 0.05). Preincubation with glibenclamide, propranolol, phentolamine or L-NAME in contractions induced by carbachol did not alter significantly the relaxing effect of LOO. However, in the presence of 4-aminopyridine, CsCl or tetraethylammonium there was a reduction of LOO potency, whereas the blockers methylene blue, ODQ, aminophylline and heparin potentiated the LOO relaxing effect. Preincubation with LOO in a Ca2+ free medium at concentrations of 27 μg/mL or 81 μg/mL reduced the contraction induced by carbachol. The administration of LOO for 3 days did not alter uterus contractility. The treatment with LOO at 30 or 100 mg/kg intraperitoneally, or 100 mg/kg orally, inhibited writhing in female mice. The association of LOO at 10 mg/kg with nifedipine or mefenamic acid potentiated writhing inhibition in mice. CONCLUSIONS The essential oil of L. origanoides has tocolytic activity in rat isolated uterus pre-contracted with KCl, oxytocin, or carbachol. This effect is possibly related to the opening of potassium channels (Kir, KV, and KCa), cAMP increase, and diminution of intracellular Ca2+. This relaxant effect, probably, contributed to reduce the number of writhings in an animal model of dysmenorrhea being potentiated by nifedipine or mefenamic acid. Taken together, the results here presented indicate that this species has a pharmacological potential for the treatment of primary dysmenorrhea, supporting its use in folk medicine.
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Affiliation(s)
| | - Gabriela Olinda de Paiva
- Laboratório de Farmacologia Experimental, Colegiado de Farmácia, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil.
| | - Pedro Modesto Nascimento Menezes
- Laboratório de Farmacologia Experimental, Colegiado de Farmácia, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil; Rede Nordeste de Biotecnologia, Universidade Federal Rural de Pernambuco (UFRPE), Brazil.
| | - Tiago Feitosa Ribeiro
- Rede Nordeste de Biotecnologia, Universidade Federal Rural de Pernambuco (UFRPE), Brazil.
| | - Mariana Coelho Brito
- Laboratório de Farmacologia Experimental, Colegiado de Farmácia, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil.
| | | | | | | | - Angélica Maria Lucchese
- Laboratório de Química de Produtos Naturais e Bioativos, Departamento de Ciências Exatas, Universidade Estadual de Feira de Santana (UEFS), Brazil.
| | - Julianeli Tolentino de Lima
- Laboratório de Farmacologia Experimental, Colegiado de Farmácia, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil.
| | - Fabrício Souza Silva
- Pós-graduação em Biociênicas, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil; Laboratório de Farmacologia Experimental, Colegiado de Farmácia, Universidade Federal do Vale do São Francisco (UNIVASF), Brazil.
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Asif H, Barnett SD, Buxton ILO. Title: β3 Adrenergic Receptor Signaling in the Human Myometrium. Reprod Sci 2022; 30:124-134. [PMID: 35380411 PMCID: PMC8980516 DOI: 10.1007/s43032-022-00917-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 03/11/2022] [Indexed: 01/06/2023]
Abstract
Preterm labor leading to preterm birth is the leading cause of infant morbidity and mortality. Although β2 adrenergic agonists fail to provide adequate tocolysis, the expression of the β3 adrenergic receptor in myometrium and its unique signaling suggest a role for β3 agonist in the management of preterm labor. Western blot analysis showed that the β3 adrenergic receptor expression increased in human pregnancy myometrium compared to nonpregnant tissues (p < 0.0001). There was no difference in β3 adrenergic receptor expression throughout pregnancy (p > 0.05). The addition of the β3 agonist mirabegron in the tissue bath relaxed oxytocin contracted myometrium with an EC50 of 41.5 µM. Relaxation was partially blocked by the addition of the eNOS blocker Nω-nitro-L-arginine, or the large conductance potassium channel blocker paxilline. Combination of Nω-nitro-L-arginine and paxilline prevented mirabegron-mediated relaxation. Imaging revealed that the β3 adrenergic receptors are expressed by both myocyte and microvascular endothelial cells isolated from human myometrium. Nitric oxide production measured by 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate revealed that mirabegron stimulated nitric oxide production in myometrial endothelial cells. These data suggest that both endothelial and smooth muscle cells contribute to relaxation through disparate signaling pathways. Repurposing of approved medications tested in human myometrium as uterine tocolytics can advance prevention of preterm birth. These data argue that further examination of β3 adrenergic receptor signaling in myometrium may reveal mirabegron as a useful tocolytic in combination tocolysis regimens.
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Affiliation(s)
- Hazik Asif
- School of Medicine, Department of Pharmacology, Myometrial Function Laboratory, University of Nevada, Reno, NV 89557-0318 USA
| | - Scott D. Barnett
- School of Medicine, Department of Pharmacology, Myometrial Function Laboratory, University of Nevada, Reno, NV 89557-0318 USA
| | - Iain L. O. Buxton
- School of Medicine, Department of Pharmacology, Myometrial Function Laboratory, University of Nevada, Reno, NV 89557-0318 USA
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Barnett SD, Asif H, Anderson M, Buxton ILO. Novel Tocolytic Strategy: Modulating Cx43 Activity by S-Nitrosation. J Pharmacol Exp Ther 2021; 376:444-453. [PMID: 33384302 PMCID: PMC7919864 DOI: 10.1124/jpet.120.000427] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 12/23/2020] [Indexed: 12/13/2022] Open
Abstract
Currently available tocolytics are ineffective at significantly delaying preterm birth. This is due in part to our failure to better understand the mechanisms that drive spontaneous preterm labor (sPTL). Cyclic nucleotides are not the primary contributors to myometrial quiescence, but instead nitric oxide (NO)-mediated protein S-nitrosation (SNO) is integral to the relaxation of the tissue. Connexin-43 (Cx43), a myometrial "contractile-associated protein" that functions as either a gap junction channel or an hemichannel (HC), was the focus of this study. Protein analysis determined that Cx43 is downregulated in sPTL myometrium. Furthermore, Cx43 is S-nitrosated by NO, which correlates with an increase of phosphorylated Cx43 at serine 368 (Cx43-pS368 -gap junction inhibition) as well as an increase in the HC open-state probability (quiescence). Pharmacologic inhibition of Cx43 with 18β-glycyrrhetinic acid (18β-GA) exhibits a negative inotropic effect on the myometrium in a dose-dependent manner, as does administration of nebivolol, an NO synthase activator that increases total protein SNOs. When 18β-GA and nebivolol were coadministered at their IC50 values, the effect on contractile dynamics was additive and all but eliminated contractions. The development of new tocolytics demands a better understanding of the underlying mechanisms of sPTL. Here it has been shown that 18β-GA and nebivolol leverage dysregulated pathways in the myometrium, resulting in a novel approach for the treatment of sPTL. SIGNIFICANCE STATEMENT: Although there are many known causes of preterm labor (PTL), the mechanisms of "spontaneous" PTL (sPTL) remain obfuscated, which is why treating this condition is so challenging. Here we have identified that connexin-43 (Cx43), an important contractile-associated protein, is dysregulated in sPTL myometrium and that the pharmacologic inhibition of Cx43 and its S-nitrosation with 18β-glycyrrhetinic acid and nebivolol, respectively, significantly blunts contraction in human myometrial tissue, presenting a novel approach to tocolysis that leverages maladjusted pathways in women who experience sPTL.
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Affiliation(s)
- Scott D Barnett
- Department of Pharmacology, Myometrial Function Group, University of Nevada, Reno School of Medicine, Reno, NV
| | - Hazik Asif
- Department of Pharmacology, Myometrial Function Group, University of Nevada, Reno School of Medicine, Reno, NV
| | - Mitchell Anderson
- Department of Pharmacology, Myometrial Function Group, University of Nevada, Reno School of Medicine, Reno, NV
| | - Iain L O Buxton
- Department of Pharmacology, Myometrial Function Group, University of Nevada, Reno School of Medicine, Reno, NV
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Ulrich CC, Arinze V, Wandscheer CB, Copley Salem C, Nabati C, Etezadi-Amoli N, Burkin HR. Matrix metalloproteinases 2 and 9 are elevated in human preterm laboring uterine myometrium and exacerbate uterine contractility†. Biol Reprod 2020; 100:1597-1604. [PMID: 30951583 DOI: 10.1093/biolre/ioz054] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 02/15/2019] [Accepted: 04/03/2019] [Indexed: 12/14/2022] Open
Abstract
Matrix metalloproteinases 2 and 9 (MMP2/9) have previously been shown to be elevated in serum and amniotic fluid from women undergoing preterm birth. We performed experiments to determine the effects of MMP2/9 on uterine contraction and birth timing. Pregnant mice were injected daily with 50 mg/kg of SB-3CT or vehicle control beginning on gestational day 14-18 to determine if MMP2/9 inhibition would affect parturition timing. MMP2/9 expression in human myometrial tissue was determined by Simple Western (Wes) and semiquantitative western blot. Purified MMP2/9 and SB-3CT inhibitor were added to human myometrial strips to determine the effects of MMP2/9 on oxytocin-induced uterine contraction. Parturition was delayed in mice treated with MMP2/9 inhibitor SB-3CT. MMP2/9 protein levels were elevated in preterm laboring uterine myometrium. Gelatinase activity was confirmed in cell extracts and supernatants from immortalized and primary human uterine myometrial cells in culture. Addition of purified MMP2/9 increased the oxytocin-induced contractile response in myometrial tissue strips from pregnant women. In contrast, addition of the MMP2/9 inhibitor SB-3CT decreased the contractile response to oxytocin in a dose-dependent manner. These results suggest abnormal MMP2/9 expression affects the contractile state of the uterine myometrium to promote parturition and that MMP2/9 inhibition attenuates this effect.
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Affiliation(s)
- Craig C Ulrich
- University of Nevada, Reno School of Medicine, Department of Pharmacology, Reno, Nevada, USA
| | - Veronica Arinze
- University of Nevada, Reno School of Medicine, Department of Pharmacology, Reno, Nevada, USA
| | | | - Christian Copley Salem
- University of Nevada, Reno School of Medicine, Department of Pharmacology, Reno, Nevada, USA
| | - Camellia Nabati
- University of Nevada, Reno School of Medicine, Department of Pharmacology, Reno, Nevada, USA
| | - Neda Etezadi-Amoli
- University of Nevada, Reno School of Medicine, Department of Obstetrics and Gynecology, Reno, Nevada, USA
| | - Heather R Burkin
- University of Nevada, Reno School of Medicine, Department of Pharmacology, Reno, Nevada, USA
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Centner AM, Bhide PG, Salazar G. Nicotine in Senescence and Atherosclerosis. Cells 2020; 9:E1035. [PMID: 32331221 PMCID: PMC7226537 DOI: 10.3390/cells9041035] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/08/2020] [Accepted: 04/16/2020] [Indexed: 12/22/2022] Open
Abstract
Cigarette smoke is a known exacerbator of age-related pathologies, such as cardiovascular disease (CVD), atherosclerosis, and cellular aging (senescence). However, the role of nicotine and its major metabolite cotinine is yet to be elucidated. Considering the growing amount of nicotine-containing aerosol use in recent years, the role of nicotine is a relevant public health concern. A number of recent studies and health education sites have focused on nicotine aerosol-induced adverse lung function, and neglected cardiovascular (CV) impairments and diseases. A critical review of the present scientific literature leads to the hypothesis that nicotine mediates the effects of cigarette smoke in the CV system by increasing MAPK signaling, inflammation, and oxidative stress through NADPH oxidase 1 (Nox1), to induce vascular smooth muscle cell (VSMC) senescence. The accumulation of senescent VSMCs in the lesion cap is detrimental as it increases the pathogenesis of atherosclerosis by promoting an unstable plaque phenotype. Therefore, nicotine, and most likely its metabolite cotinine, adversely influence atherosclerosis.
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Affiliation(s)
- Ann Marie Centner
- Department of Nutrition, Food and Exercise Sciences, College of Human Scinces, 120 Convocation Way, Florida State University, Tallahassee, FL 32306, USA;
| | - Pradeep G. Bhide
- Department of Biomedical Sciences, FSU College of Medicine, 1115, West Call Street, Tallahassee, FL 32306, USA;
| | - Gloria Salazar
- Department of Nutrition, Food and Exercise Sciences, College of Human Scinces, 120 Convocation Way, Florida State University, Tallahassee, FL 32306, USA;
- Center for Advancing Exercise and Nutrition Research on Aging (CAENRA), Florida State University, Tallahassee, FL 32306, USA
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Butler TA, Paul JW, Smith R. Non-conventional signalling in human myometrium by conventional pathways: looking back for a synergistic future. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2019.11.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Modzelewska B, Jóźwik M, Jóźwik M, Tylicka M, Kleszczewski T. The effects of extended nitric oxide release on responses of the human non-pregnant myometrium to endothelin-1 or vasopressin. Pharmacol Rep 2019; 71:892-898. [PMID: 31419630 DOI: 10.1016/j.pharep.2019.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 04/12/2019] [Accepted: 05/06/2019] [Indexed: 11/30/2022]
Abstract
BACKGROUND Uterotonic mediators: endothelin-1 (ET-1), arginine vasopressin (AVP), and nitric oxide (NO) play important roles in the regulation of uterine contractility. We hypothesize that NO affects both ET-1 or AVP. Therefore, this study investigated the involvement of extended exogenous NO release in the regulation of responses of the human non-pregnant myometrium to ET-1 and AVP. METHODS Specimens were obtained from 10 premenopausal women, undergoing hysterectomy for benign gynecological disorders. Responses of the myometrial strips to ET-1 or AVP in the absence and presence of an exogenous NO donor (diethylenetriamine; DETA/NO; 10-4 mol/L) were recorded under isometric conditions. To inhibit endogenous NO, a competitive inhibitor of NO synthase, L-NG-nitroarginine (L-NNA) was added to the organ bath. RESULTS ET-1 enhanced the spontaneous contractile activity of the myometrium more powerfully (p < 0.01) than AVP. Preincubation with exogenous NO weakened ET-1- or AVP-induced increases in this contractile activity (p < 0.05). However, unexpected results were obtained after preincubation with L-NNA and with DETA/NO then added. Both ET-1 and AVP induced augmented contractile effects in almost all concentrations compared with the responses to these peptides alone or after NOS synthase inhibition (both p < 0.01). CONCLUSIONS This study demonstrated for the first time that extended incubation with a NO donor influences the uterine muscle response evoked by ET-1 and AVP. Both endogenous and exogenous NO is involved in the control of the uterine responses to ET-1 or AVP of non-pregnant myometrium. Furthermore, both peptides stimulate increased uterine contractility when the local imbalance between the constrictive and relaxing mediators takes place.
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Affiliation(s)
- Beata Modzelewska
- Department of Biophysics, Medical University of Białystok, Białystok, Poland.
| | - Maciej Jóźwik
- Department of Gynecology and Gynecologic Oncology, Medical University of Białystok, Białystok, Poland
| | - Marcin Jóźwik
- Department of Gynecology and Obstetrics, Faculty of Medical Sciences, University of Warmia and Mazury, Olsztyn, Poland
| | - Marzena Tylicka
- Department of Biophysics, Medical University of Białystok, Białystok, Poland
| | - Tomasz Kleszczewski
- Department of Biophysics, Medical University of Białystok, Białystok, Poland
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Changes in Gastric Smooth Muscle Cell Contraction during Pregnancy: Effect of Estrogen. J Pregnancy 2019; 2019:4302309. [PMID: 31080672 PMCID: PMC6475543 DOI: 10.1155/2019/4302309] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 03/14/2019] [Indexed: 12/19/2022] Open
Abstract
It is well known that pregnancy is associated with frequent gastrointestinal (GI) disorders and symptoms. Moreover, previous reports have shown that estrogen, which changes in levels during pregnancy, participates in the regulation of GI motility and is involved in the pathogenesis of various functional disorders in the stomach. The aim of the current study was to explore the changes in the expression of estrogen receptors (ERs) and examine the effect of estrogen on nitric oxide- (NO-) cyclic guanosine monophosphate (cGMP) pathway and thus relaxation in gastric smooth muscle cells (GSMC) during pregnancy. Single GSMC from early-pregnant and late-pregnant Sprague-Dawley rats were used. Protein and mRNA expression levels of ERs were measured via specifically designed enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR), respectively. NO and cGMP levels were measured via specifically designed ELISA kits. Effect of estrogen on acetylcholine- (ACh-) induced contraction of single GSMC was measured via scanning micrometry in the presence or absence of the NO synthase inhibitor, N-nitro-L-arginine (L-NNA), or guanylyl cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ). Estrogen increased both NO and cGMP levels and their levels were greater in early compared to late pregnancy. Expression of ERs was greater in early compared to late pregnancy. ACh induced greater contraction of GSMC in late pregnancy compared to early pregnancy. Estrogen inhibited ACh-induced contraction in both periods of pregnancy. Importantly, pretreatment of GSMC with either L-NNA or ODQ abolished estrogen inhibitory action on muscle contraction. In conclusion, GSMC contractile behavior undergoes drastic changes in response to estrogen during pregnancy and this might explain some of the pregnancy-associated gastric disorders.
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Gupta H, Deshpande SB. Bisphenol A decreases the spontaneous contractions of rat uterus in vitro through a nitrergic mechanism. J Basic Clin Physiol Pharmacol 2019; 29:593-598. [PMID: 29768248 DOI: 10.1515/jbcpp-2017-0068] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Accepted: 03/26/2018] [Indexed: 01/25/2023]
Abstract
BACKGROUND Bisphenol A (BPA), a chemical used in the manufacture of plastics, has toxic effects on various systems of the human body including the reproductive system. BPA possesses estrogenic activity and is implicated in altering oogenesis, ovulation, and fertility. In addition to ovulatory changes, uterine contractility is an important factor for fertility. However, the effects of BPA on myometrial contractions are not known. Therefore, we examined the effect of BPA on rat uterine contractions. METHODS The uterus was isolated from adult rats showing estrous phase, and spontaneous in vitro contractions were recorded (35±1 °C). The effect of cumulative concentrations of BPA was determined. Further, the involvement of nitric oxide (NO) and guanylyl cyclase (GC) for the BPA-induced changes on uterine contractility was evaluated using the NO synthase inhibitor (L-NAME) or GC inhibitor (methylene blue). RESULTS BPA decreased the amplitude and frequency of spontaneous uterine contractions in a concentration-dependent manner. A decrease of 50% occurred at 1 and 3 μM for amplitude and frequency, respectively. L-NAME (N-ω-nitro-l-arginine methyl ester) blocked the BPA-induced decrease in amplitude at all concentrations but antagonized the frequency only at the maximum concentration (10 μM). Methylene blue (a GC inhibitor) did not block the BPA-induced responses but for the frequency at 10 μM of BPA. CONCLUSIONS The results indicate that BPA decreased the amplitude and frequency of spontaneous uterine contractions by involving the nitrergic mechanism; however, the GC mechanism is not involved in the depression.
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Affiliation(s)
- Hemlata Gupta
- Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Shripad B Deshpande
- Department of Physiology, SRMS-Institute of Medical Sciences, Bareilly-243202, UP, India.,Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi-221005, India, Phone: +91-9450530236, Fax: +91-581-2582030
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Lysophosphatidic acid enhances PGE2 to PGF2α ratio and nitric oxide level in nonpregnant buffalo uterus. Theriogenology 2018; 120:47-55. [PMID: 30092374 DOI: 10.1016/j.theriogenology.2018.07.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 07/10/2018] [Accepted: 07/16/2018] [Indexed: 01/24/2023]
Abstract
Lysophosphatidic acid (LPA) is a small ubiquitous lipid exerting diverse biological functions. Its role in reproduction in different species has created great interest in recent times. In the present study, we aimed to elucidate LPA signaling in nonpregnant buffalo uterus by in vitro studies. Standard techniques like real-time PCR (for mRNA expression of LPARs and COX-2 and iNOS), Western blot (for PPARγ protein expression), sandwich ELISA (for PGE2 and PGF2α assay) and histopathology (for assessment of endometrial architecture in culture) were used in this study. The buffalo uterine tissues were collected from the local slaughterhouse and were selected for the study on the basis of the presence of corpus luteum on the ovary (n = 5). The LPAR3 receptor was the highest expressed receptor as compared to LPAR1 and LPAR6 in non-pregnant uterine tissues after 6 h incubation in Dulbecco's Modified Eagle Medium (DMEM). 50 μM LPA increased the mRNA expressions of COX-2 and iNOS enzymes which were attenuated by the treatment of LPAR1/3 antagonist Ki16425. PPARγ antagonist GW9662 prevented the LPA-induced increase in iNOS mRNA expression but did not alter the COX-2 expression. LPA also enhanced the PGE2 to PGF2α ratio in uterine tissue homogenates which was inhibited by all the receptor antagonists as well as by the inhibitors of COX-2 and iNOS. LPA also increased the total nitrite level in tissue homogenates in LPAR1/3- and iNOS-dependent manner. Additionally, we demonstrate PPARγ mRNA and protein expressions in nonpregnant buffalo endometrium. In conclusion, the results of the present study suggest that LPA acts as a luteotropic factor during the estrus cycle in nonpregnant buffalo uterus by enhancing PGE2 to PGF2α ratio and NO level through multiple receptors.
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Barnett SD, Buxton ILO. Hiding in Plain Sight: Nebivolol Exhibits Compelling Tocolytic Properties. J Cell Mol Med 2018; 22:6391-6395. [PMID: 30188599 PMCID: PMC6237580 DOI: 10.1111/jcmm.13883] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 08/06/2018] [Indexed: 01/12/2023] Open
Abstract
Preterm birth before 37 weeks of completed gestation results in numerous health consequences for the foetus. Preterm labour leads to preterm birth in over 50% of cases, and no FDA‐approved treatment can prevent labour or help a foetus remain in the womb until term. Examination of nitric oxide mediated relaxation signaling in the uterine smooth muscle reveals a role for protein S‐nitrosation. The recent discovery of upregulated S‐nitrosoglutathione reductase (GSNOR) in spontaneously preterm labouring women has emphasized the need to explore the function of S‐nitrosation regulation in the maintenance of uterine quiescence. Here we have examined the ability of nebivolol to relax uterine smooth muscle and tested recent claims that nebivolol is a GSNOR inhibitor. In uterine smooth muscle strips from both mouse and human, nebivolol relaxes oxytocin‐induced contractions in a dose dependent manner. Our data indicates that nebivolol has no effect on GSNOR activity, nor does nebivolol inhibit thioredoxin reductase, two of the major protein denitrosylases. The ability of nebivolol to relax uterine smooth muscle is likely the combined effects of increased nitric oxide synthase activity and β3‐adregnegic stimulation.
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Affiliation(s)
- Scott D Barnett
- Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Iain L O Buxton
- Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada
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S-Nitrosoglutathione Reductase Underlies the Dysfunctional Relaxation to Nitric Oxide in Preterm Labor. Sci Rep 2018; 8:5614. [PMID: 29618799 PMCID: PMC5884813 DOI: 10.1038/s41598-018-23371-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 03/06/2018] [Indexed: 12/11/2022] Open
Abstract
Tocolytics show limited efficacy to prevent preterm delivery. In uterine smooth muscle cGMP accumulation following addition of nitric oxide (NO) has little effect on relaxation suggesting a role for protein S-nitrosation. In human myometrial tissues from women in labor at term (TL), or spontaneously in labor preterm (sPTL), direct stimulation of soluble guanylyl cyclase (sGC) fails to relax myometrium, while the same treatment relaxes vascular smooth muscle completely. Unlike term myometrium, effects of NO are not only blunted in sPTL, but global protein S-nitrosation is also diminished, suggesting a dysfunctional response to NO-mediated protein S-nitrosation. Examination of the enzymatic regulator of endogenous S-nitrosoglutathione availability, S-nitrosoglutathione reductase, reveals increased expression of the reductase in preterm myometrium associated with decreased total protein S-nitrosation. Blockade of S-nitrosoglutathione reductase relaxes sPTL tissue. Addition of NO donor to the actin motility assay attenuates force. Failure of sGC activation to mediate relaxation in sPTL tissues, together with the ability of NO to relax TL, but not sPTL myometrium, suggests a unique pathway for NO-mediated relaxation in myometrium. Our results suggest that examining the action of S-nitrosation on critical contraction associated proteins central to the regulation of uterine smooth muscle contraction can reveal new tocolytic targets.
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Barnett SD, Buxton ILO. The role of S-nitrosoglutathione reductase (GSNOR) in human disease and therapy. Crit Rev Biochem Mol Biol 2017; 52:340-354. [PMID: 28393572 PMCID: PMC5597050 DOI: 10.1080/10409238.2017.1304353] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
S-nitrosoglutathione reductase (GSNOR), or ADH5, is an enzyme in the alcohol dehydrogenase (ADH) family. It is unique when compared to other ADH enzymes in that primary short-chain alcohols are not its principle substrate. GSNOR metabolizes S-nitrosoglutathione (GSNO), S-hydroxymethylglutathione (the spontaneous adduct of formaldehyde and glutathione), and some alcohols. GSNOR modulates reactive nitric oxide (•NO) availability in the cell by catalyzing the breakdown of GSNO, and indirectly regulates S-nitrosothiols (RSNOs) through GSNO-mediated protein S-nitrosation. The dysregulation of GSNOR can significantly alter cellular homeostasis, leading to disease. GSNOR plays an important regulatory role in smooth muscle relaxation, immune function, inflammation, neuronal development and cancer progression, among many other processes. In recent years, the therapeutic inhibition of GSNOR has been investigated to treat asthma, cystic fibrosis and interstitial lung disease (ILD). The direct action of •NO on cellular pathways, as well as the important regulatory role of protein S-nitrosation, is closely tied to GSNOR regulation and defines this enzyme as an important therapeutic target.
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Affiliation(s)
- Scott D Barnett
- a Department of Pharmacology , University of Nevada, Reno School of Medicine , Reno , NV , USA
| | - Iain L O Buxton
- a Department of Pharmacology , University of Nevada, Reno School of Medicine , Reno , NV , USA
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Khan FA, Chenier TS, Murrant CL, Foster RA, Hewson J, Scholtz EL. Dose-dependent inhibition of uterine contractility by nitric oxide: A potential mechanism underlying persistent breeding-induced endometritis in the mare. Theriogenology 2016; 90:59-64. [PMID: 28166989 DOI: 10.1016/j.theriogenology.2016.11.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 11/20/2016] [Accepted: 11/26/2016] [Indexed: 11/17/2022]
Abstract
Nitric oxide (NO) may have a role in persistent breeding-induced endometritis in mares through an inhibitory effect on uterine contractility. The objectives of this study were to test the effect of NO on spontaneous uterine contractility in-vitro and to evaluate whether this effect varied between the longitudinal and circular muscle layers of the uterus. Reproductive tracts were collected from eight euthanized non-pregnant mares (age 4-19 years; body weight 405-530 kg). Transrectal examination of the reproductive tract was performed before euthanasia to evaluate stage of the estrous cycle and presence of any apparent abnormality. After euthanasia, one uterine tissue sample was collected for histological evaluation and four full-thickness uterine tissue strips (10-12 mm × 2 mm), two parallel to each muscle layer, were excised for in-vitro contractility evaluation. Strips were suspended in tissue chambers containing Krebs-Henseleit solution, with continuous aeration (95% O2-5% CO2; pH 7.4) at 37 °C. After equilibration, spontaneous contractility was recorded (pre-treatment) and strips excised in each direction were randomly allocated to each of two groups: 1) SNAP (S-nitroso-N-acetylpenicillamine, an NO donor); or 2) NAP (N-acetyl-d-penicillamine, vehicle and time-matched control). These were treated at 15 min intervals with increasing concentrations (10-7 M to 10-3 M) of SNAP and NAP, respectively. Contractility data was recorded throughout the experiment. An interaction effect of group-by-concentration was observed (P < 0.0001). The mean contractility after treatment with 10-4 M and 10-3 M SNAP were significantly lower than the pre-treatment contractility and the mean contractility after treatment with lower SNAP concentrations. In contrast, contractility did not change significantly in the NAP treated controls. The effect of treatment on uterine contractility was not influenced by age or weight of the mare, stage of estrous cycle, uterine histology grade, or muscle layer. Secondary findings included significant main effects of stage of estrous cycle (increased contractility in estrus compared to diestrus), uterine histology grade (decreased contractility in grade IIB compared to grade I) and age (decreased contractility in mares aged > 8 years compared to mares aged ≤ 8 years). In conclusion, results of this study indicate that NO has a dose-dependent inhibitory effect on spontaneous uterine contractility irrespective of the muscle layer in the mare.
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Affiliation(s)
- Firdous A Khan
- Department of Population Medicine, University of Guelph, Canada.
| | | | - Coral L Murrant
- Department of Human Health and Nutritional Sciences, University of Guelph, Canada
| | | | - Joanne Hewson
- Department of Clinical Studies, University of Guelph, Canada
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Khan FA, Scholtz EL, Chenier TS. The Nitric Oxide System in Equine Reproduction: Current Status and Future Directions. J Equine Vet Sci 2015. [DOI: 10.1016/j.jevs.2015.02.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Berenyiova A, Grman M, Mijuskovic A, Stasko A, Misak A, Nagy P, Ondriasova E, Cacanyiova S, Brezova V, Feelisch M, Ondrias K. The reaction products of sulfide and S-nitrosoglutathione are potent vasorelaxants. Nitric Oxide 2014; 46:123-30. [PMID: 25529482 DOI: 10.1016/j.niox.2014.12.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 12/02/2014] [Accepted: 12/15/2014] [Indexed: 12/28/2022]
Abstract
The chemical interaction of sodium sulfide (Na2S) with the NO-donor S-nitrosoglutathione (GSNO) has been described to generate new reaction products, including polysulfides and nitrosopersulfide (SSNO(-)) via intermediacy of thionitrous acid (HSNO). The aim of the present work was to investigate the vascular effects of the longer-lived products of the Sulfide/GSNO interaction. Here we show that the products of this reaction relax precontracted isolated rings of rat thoracic aorta and mesenteric artery (but to a lesser degree rat uterus) with a >2-fold potency compared with the starting material, GSNO (50 nM), whereas Na2S and polysulfides have little effect at 1-5 µM. The onset of vasorelaxation of the reaction products was 7-10 times faster in aorta and mesenteric arteries compared with GSNO. Relaxation to GSNO (100-500 nM) was blocked by an inhibitor of soluble guanylyl cyclase, ODQ (0.1 and 10 µM), and by the NO scavenger cPTIO (100 µM), but less affected by prior acidification (pH 2-4), and unaffected by N-acetylcysteine (1 mM) or methemoglobin (20 µM heme). By contrast, relaxation to the Sulfide/GSNO reaction products (100-500 nM based on the starting material) was inhibited to a lesser extent by ODQ, only slightly decreased by cPTIO, more markedly inhibited by methemoglobin and N-acetylcysteine, and abolished by acidification before addition to the organ bath. The reaction mixture was found to generate NO as detected by EPR spectroscopy using N-(dithiocarboxy)-N-methyl-D-glucamine (MGD2)-Fe(2+) as spin trap. In conclusion, the Sufide/GSNO reaction products are faster and more pronounced vasorelaxants than GSNO itself. We conclude that in addition to NO formation from SSNO(-), reaction products other than polysulfides may give rise to nitroxyl (HNO) and be involved in the pronounced relaxation induced by the Sulfide/GSNO cross-talk.
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Affiliation(s)
- Andrea Berenyiova
- Institute of Normal and Pathological Physiology SAS, Sienkiewiczova 1, 81371 Bratislava, Slovakia
| | - Marian Grman
- Institute of Molecular Physiology and Genetics SAS, Vlarska 5, 83334 Bratislava, Slovakia; Center for Molecular Medicine SAS, Vlarska 7, 83101 Bratislava, Slovakia
| | - Ana Mijuskovic
- Institute for Biological Research "Siniša Stanković", University of Belgrade, Blvd Despota Stefana 142, Belgrade, Serbia
| | - Andrej Stasko
- Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinskeho 9, 81237 Bratislava, Slovakia
| | - Anton Misak
- Institute of Molecular Physiology and Genetics SAS, Vlarska 5, 83334 Bratislava, Slovakia
| | - Peter Nagy
- Department of Molecular Immunology and Toxicology, National Institute of Oncology, Ráth György utca 7-9, Budapest, 1122 Hungary
| | - Elena Ondriasova
- Faculty of Pharmacy, Comenius University, Odbojarov 10, 83232 Bratislava, Slovakia
| | - Sona Cacanyiova
- Institute of Normal and Pathological Physiology SAS, Sienkiewiczova 1, 81371 Bratislava, Slovakia
| | - Vlasta Brezova
- Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinskeho 9, 81237 Bratislava, Slovakia
| | - Martin Feelisch
- Clinical & Experimental Sciences, Faculty of Medicine, Southampton General Hospital, University of Southampton, Tremona Road, Southampton, UK
| | - Karol Ondrias
- Institute of Molecular Physiology and Genetics SAS, Vlarska 5, 83334 Bratislava, Slovakia.
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Terranova C, Petrella C, Improta G, Severini C, Signore F, Damiani P, Plotti F, Scarpignato C, Angioli R. Relaxant effect of proton pump inhibitors on in vitro myometrium from pregnant women. Eur J Pharm Sci 2014; 52:125-31. [DOI: 10.1016/j.ejps.2013.10.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 09/30/2013] [Accepted: 10/15/2013] [Indexed: 10/26/2022]
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20
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Kupittayanant S, Munglue P, Lijuan W, Promprom W, Budhaklala N, Wray S. Finding new agents in medicinal plants to act on the myometrium. Exp Physiol 2014; 99:530-7. [DOI: 10.1113/expphysiol.2013.072884] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Sajeera Kupittayanant
- Institute of Science; Suranaree University of Technology; Muang District Nakhon Ratchasima Thailand
| | - Phukphon Munglue
- Faculty of Science; Ubon Ratchathani Rajabhat University; Muang District Ubon Ratchathani Thailand
| | - Wanwisa Lijuan
- Faculty of Science and Technology; Thepsatri Rajabhat University; Muang Lop Buri Lobburi Thailand
| | - Wilawan Promprom
- Faculty of Science; Mahasarakham University; Kantrawichai Mahasarakham Thailand
| | - Nopparat Budhaklala
- Faculty of Science; Rajamangala University of Technology Thanyaburi; Thanyaburi Pathum Thani Thailand
| | - Susan Wray
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool UK
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Turgut NH, Temiz TK, Turgut B, Karadas B, Parlak M, Bagcivan I. Investigation of the role of the NO-cGMP pathway on YC-1 and DEA/NO effects on thoracic aorta smooth muscle responses in a rat preeclampsia model. Can J Physiol Pharmacol 2013; 91:797-803. [PMID: 24144050 DOI: 10.1139/cjpp-2013-0086] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study was designed to investigate the effects of YC-1, a nitric oxide (NO)-independent soluble guanylate cyclase (sGC) activator, and DEA/NO, a NO donor, on smooth muscle responses in the preeclampsia model with suramin-treated rats and on the levels of cyclic guanosine monophosphate (cGMP) of thoracic aorta rings isolated from term-pregnant rats. Rats of 2 groups, control group and suramin group, were given intraperitoneal injection of saline or suramin, respectively. Suramin injection caused increased blood pressure, protein in urine, and fetal growth retardation. Thoracic aorta rings were exposed to contractile and relaxant agents. KCl contraction and papaverine relaxation responses were similar. Relaxation responses of YC-1 and DEA/NO decreased in suramin group. In both groups in the presence of ODQ, a sGC inhibitor, the relaxation responses of YC-1 and DEA/NO decreased. The cGMP content was determined by radioimmunoassay technique. The content of cGMP in the suramin group decreased. In the presence of YC-1 and DEA/NO in both groups, cGMP content increased, but in ODQ-added groups, there was a significant decrease. We conclude that in preeclampsia, the decrease of relaxation responses and the decrease of cGMP content could be due to the reduction in stimulation of sGC and the decrease in cGMP levels.
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Affiliation(s)
- Nergiz Hacer Turgut
- a Department of Pharmacology, Faculty of Pharmacy, Cumhuriyet University, Sivas 58140, Turkey
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Munglue P, Eumkep G, Wray S, Kupittayanant S. The effects of watermelon (Citrullus lanatus) extracts and L-citrulline on rat uterine contractility. Reprod Sci 2012; 20:437-48. [PMID: 22991380 DOI: 10.1177/1933719112459223] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In uterine smooth muscle, the effects of watermelon and its citrulline content are unknown. The aims of this study were therefore, to determine the effects of watermelon extract and citrulline on the myometrium and to investigate their mechanisms of action. The effects of extracts of watermelon flesh and rind and L-citrulline (64 μmol/L) were evaluated on 3 types of contractile activity; spontaneous, those elicited by potassium chloride (KCl) depolarization, or oxytocin (10 nmol/L) application in isolated rat uterus. Inhibitors of nitric oxide (NO) and its mechanisms of action, N ω-Nitro-L-arginine methyl ester hydrochloride (L-NAME, 100 μmol/L), LY83583 (1 μmol/L), and tetraethylamonium chloride (5 mmol/L), as well as Ca signaling pathways, were determined. Both flesh and rind extracts significantly decreased the force produced by all 3 mechanisms, in a dose-dependent manner. The extracts could also significantly decrease the force under conditions of sustained high Ca levels (depolarization and agonist) and when the force was produced only by sarcoplasmic reticulum (SR) Ca release. L-citrulline produced the same effects on force as watermelon extracts. With submaximal doses of extract, the additive effects of L-citrulline were found. The inhibitory effects of extracts and L-citrulline were reversed upon the addition of NO inhibitors, and pretreatment of tissues with these inhibitors prevented the actions of both extracts and L-citrulline. Thus, these data show that watermelon and citrulline are potent tocolytics, decreasing the force produced by calcium entry and SR release and arising by different pathways, including oxytocin stimulation. Their major mechanism is to stimulate the NO-cyclic guanosine monophosphate (cGMP) relaxant pathway.
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Affiliation(s)
- Phukphon Munglue
- Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, Thailand
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Ulrich C, Quillici DR, Schegg K, Woolsey R, Nordmeier A, Buxton ILO. Uterine smooth muscle S-nitrosylproteome in pregnancy. Mol Pharmacol 2011; 81:143-53. [PMID: 22027755 DOI: 10.1124/mol.111.075804] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The molecular mechanisms involved in uterine quiescence during gestation and those responsible for induction of labor are not completely known. Nitric oxide relaxes uterine smooth muscle in a manner disparate from that for other smooth muscles because global elevation of cGMP after activation of soluble guanylyl cyclase does not relax the muscle. S-Nitrosylation, the covalent addition of an nitric oxide (NO) group to a cysteine thiol is a likely mechanism to explain the ability of NO to relax myometrium. This work is the first to describe the myometrial S-nitrosylproteome in both pregnant and nonpregnant tissue states. Using the guinea pig model, we show that specific sets of proteins involved in contraction and relaxation are S-nitrosylated in laboring and nonlaboring muscle and that many of these proteins are uniquely S-nitrosylated in only one state of the tissue. In particular, we show that S-nitrosylation of the intermediate filament protein desmin is significantly increased (5.7-fold, p < 0.005) in pregnancy and that this increase cannot be attributed solely to the increase in protein expression (1.8-fold, p < 0.005) that accompanies pregnancy. Elucidation of the myometrial S-nitrosylproteome provides a list of mechanistically important proteins that can constitute the basis of hypotheses formed to explain the regulation of uterine contraction/relaxation.
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Affiliation(s)
- Craig Ulrich
- Department of Pharmacology, University of Nevada School of Medicine, Reno, NV 89557, USA
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Rizzo A, Trisolini C, Spedicato M, Mutinati M, Minoia G, Sciorsci RL. In vitro effects of L-arginine on spontaneous and Homocysteine-induced contractility of pregnant canine uteri. Theriogenology 2011; 76:715-20. [DOI: 10.1016/j.theriogenology.2011.04.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 03/28/2011] [Accepted: 04/03/2011] [Indexed: 10/18/2022]
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Choudhury S, Garg SK, Singh TU, Mishra SK. Functional and molecular characterization of maxi K+-channels (BKCa) in buffalo myometrium. Anim Reprod Sci 2011; 126:173-8. [DOI: 10.1016/j.anireprosci.2011.05.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 05/20/2011] [Accepted: 05/30/2011] [Indexed: 11/25/2022]
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A role of stretch-activated potassium currents in the regulation of uterine smooth muscle contraction. Acta Pharmacol Sin 2011; 32:758-64. [PMID: 21642947 DOI: 10.1038/aps.2011.62] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Rates of premature birth are alarming and threaten societies and healthcare systems worldwide. Premature labor results in premature birth in over 50% of cases. Preterm birth accounts for three-quarters of infant morbidity and mortality. Children that survive birth before 34 weeks gestation often face life-long disability. Current treatments for preterm labor are wanting. No treatment has been found to be generally effective and none are systematically evaluated beyond 48 h. New approaches to the treatment of preterm labor are desperately needed. Recent studies from our laboratory suggest that the uterine muscle is a unique compartment with regulation of uterine relaxation unlike that of other smooth muscles. Here we discuss recent evidence that the mechanically activated 2-pore potassium channel, TREK-1, may contribute to contraction-relaxation signaling in uterine smooth muscle and that TREK-1 gene variants associated with human labor and preterm labor may lead to a better understanding of preterm labor and its possible prevention.
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Chiossi G, Costantine MM, Betancourt A, Hankins GD, Longo M, Saade GR, Bytautiene E. Does sildenafil citrate affect myometrial contractile response to nifedipine in vitro? Am J Obstet Gynecol 2010; 203:252.e1-5. [PMID: 20541728 DOI: 10.1016/j.ajog.2010.05.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 04/09/2010] [Accepted: 05/05/2010] [Indexed: 11/26/2022]
Abstract
OBJECTIVE We sought to test the hypothesis that sildenafil citrate (SC) at low concentrations potentiates the tocolytic effects of nifedipine in vitro. STUDY DESIGN Myometrial biopsies were obtained from 22 term nonlaboring women undergoing scheduled cesarean delivery. Tissue strips were suspended in organ chambers for isometric tension recording, and incubated for 30 minutes with either SC at 231 ng/mL or solvent. The effects of cumulative doses (10(-10) to 10(-5) mol/L) of nifedipine on spontaneous and oxytocin-induced uterine contractility were then determined. Areas under the contraction curve were compared using 1-way analysis of variance with Tukey post hoc test (significance: P < .05). RESULTS Nifedipine significantly inhibited spontaneous and oxytocin-induced myometrial contractility. Preincubation with SC increased response to nifedipine and significantly potentiated its inhibitory effect at 10(-8) mol/L, without affecting oxytocin-induced contractile response. CONCLUSION At concentrations within a therapeutic window, SC increases myometrial sensitivity to nifedipine.
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Buxton ILO, Milton D, Barnett SD, Tichenor SD. Agonist-specific compartmentation of cGMP action in myometrium. J Pharmacol Exp Ther 2010; 335:256-63. [PMID: 20651027 DOI: 10.1124/jpet.110.171934] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nitric oxide relaxes myometrium in a cGMP-independent manner. Although cGMP activates its cognate kinase, this is not required for the inhibitory effect of nitric oxide. Thus, nitric oxide-mediated cGMP elevation does not enjoy the same set of substrates as it does in other smooth muscles. To further understand the regulation of relaxation of uterine muscle by cGMP, we have studied the actions of peptide-mediated cGMP action in guinea pig myometrium. We used both functional and biochemical studies of the action of the particulate guanylyl cyclase activator uroguanylin and its receptor, particulate guanylyl cyclase type C, to address the relationship between cGMP elevation acting in the membrane signaling domain to that of the nonmembrane region of the cell. Uroguanylin relaxed oxytocin-induced contractions in a dose-dependent fashion only in pregnant myometrium. Both relaxation and cGMP accumulation after uroguanylin stimulation were blocked by the putative particulate guanylyl cyclase type C inhibitors 2-chloro-ATP and isatin (1H-indole-2,3-dione), but not by the soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-A]quinoxalin-1-one (ODQ). Uroguanylin stimulated cGMP accumulation only in the pregnant myometrium. Caveolin-1 expression increased in pregnancy toward term. In the caveolin-1-containing membrane domain, uroguanylin, but not the nitric-oxide donor, led to the elevation of cGMP that was insensitive to ODQ. Particulate guanylyl cyclase C was expressed and prouroguanylin was detected in pregnant myometrium. We conclude that a uroguanylin-particulate cyclase-cGMP relaxation pathway is present and cGMP is compartmented in myometrium. The agonist-mediated selectivity of relaxation to cGMP is of fundamental pharmacological interest in understanding signal transduction in smooth muscle.
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Affiliation(s)
- Iain L O Buxton
- Department of Pharmacology, University of Nevada School of Medicine, Reno, NV 89557, USA.
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CHOUDHURY S, GARG SK, SINGH TU, MISHRA SK. Cellular coupling of potassium channels with β2adrenoceptors in mediating myometrial relaxation in buffaloes (Bubalus bubalis). J Vet Pharmacol Ther 2010; 33:22-7. [DOI: 10.1111/j.1365-2885.2009.01084.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Carvajal JA, Delpiano AM, Cuello MA, Poblete JA, Casanello PC, Sobrevia LA, Weiner CP. Brain Natriuretic Peptide (BNP) Produced by the Human Chorioamnion May Mediate Pregnancy Myometrial Quiescence. Reprod Sci 2009; 16:32-42. [DOI: 10.1177/1933719108324137] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Jorge A. Carvajal
- Unidad de Medicina Materno Fetal, Departamento de Obstetricia y Ginecología, Pontificia Universidad Catolica de Chile, Santiago, Chile,
| | - Ana M. Delpiano
- Unidad de Medicina Materno Fetal, Departamento de Obstetricia y Ginecología, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Mauricio A. Cuello
- Unidad de Medicina Materno Fetal, Departamento de Obstetricia y Ginecología, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Jose A. Poblete
- Unidad de Medicina Materno Fetal, Departamento de Obstetricia y Ginecología, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Paola C. Casanello
- Department of Obstetrics and Gynecology, Faculty of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Luis A. Sobrevia
- Department of Obstetrics and Gynecology, Faculty of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Carl P. Weiner
- Department of Obstetrics and Gynecology, University of Kansas School of Medicine, Kansas City, Kansas
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Effets pharmacologiques de Ziziphus mauritiana Lam. (Rhamnacées) sur la pression artérielle de lapin. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s10298-008-0322-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Aaronson PI, Sarwar U, Gin S, Rockenbauch U, Connolly M, Tillet A, Watson S, Liu B, Tribe RM. A role for voltage-gated, but not Ca2+-activated, K+ channels in regulating spontaneous contractile activity in myometrium from virgin and pregnant rats. Br J Pharmacol 2006; 147:815-24. [PMID: 16415906 PMCID: PMC1751504 DOI: 10.1038/sj.bjp.0706644] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The roles of voltage-gated (K(V)) and large conductance Ca2+-activated K+ (BK(Ca)) channels in regulating basal contractility in myometrial smooth muscle are unresolved. The aim of this study was to determine the effects of inhibition of these channels on spontaneous rhythmic contraction in myometrial strips from four groups of rats: nonpregnant and during early (day 7), mid- (day 14), and late (day 21) pregnancy. BK(Ca) channels were inhibited using iberiotoxin (1-100 nM), paxilline (1-10 microM) or penitrem A (1-500, or 3000 nM); K(V) channels were inhibited using tetraethylammonium (TEA; 1-10 mM) and/or 4-aminopyridine (4-AP; 1-5 mM). Contractility was assessed as mean integral tension (MIT). Time/vehicle controls were also performed. None of the selective BK(Ca) channel inhibitors significantly affected contractility in myometrial strips from either nonpregnant or pregnant animals. 4-AP caused concentration-dependent increases in MIT in myometrium in all four groups. TEA (5 and 10 mM) significantly increased MIT in myometrium from nonpregnant, and mid- and late pregnant rats, but not in myometrium from early pregnant rats. TEA and 4-AP still caused an increase in MIT following treatment with 3000 nM penitrem A or a combination of propranolol, phentolamine, atropine (all 1 microM) and capsaicin (10 microM) in myometrial strips from nonpregnant rats. These results indicate that whereas BK(Ca) channels play little or no part in controlling basal rhythmicity in rat myometrium, K(V) channels appear to play a crucial role in this regard, especially during mid- and late pregnancy.
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Affiliation(s)
| | - Uzma Sarwar
- Division of Reproductive Health, Endocrinology and Development, King's College London, MFRU, 10th Floor NW, St Thomas' Hospital Campus, Lambeth Palace Road, London SE1 7EH
| | - Stephanie Gin
- Division of Reproductive Health, Endocrinology and Development, King's College London, MFRU, 10th Floor NW, St Thomas' Hospital Campus, Lambeth Palace Road, London SE1 7EH
| | - Uli Rockenbauch
- Division of Asthma, Allergy and Lung Biology, King's College London, London
| | - Michelle Connolly
- Division of Asthma, Allergy and Lung Biology, King's College London, London
| | - Alexandra Tillet
- Division of Reproductive Health, Endocrinology and Development, King's College London, MFRU, 10th Floor NW, St Thomas' Hospital Campus, Lambeth Palace Road, London SE1 7EH
| | - Sarah Watson
- Division of Reproductive Health, Endocrinology and Development, King's College London, MFRU, 10th Floor NW, St Thomas' Hospital Campus, Lambeth Palace Road, London SE1 7EH
| | - Bing Liu
- Division of Reproductive Health, Endocrinology and Development, King's College London, MFRU, 10th Floor NW, St Thomas' Hospital Campus, Lambeth Palace Road, London SE1 7EH
| | - Rachel Marie Tribe
- Division of Reproductive Health, Endocrinology and Development, King's College London, MFRU, 10th Floor NW, St Thomas' Hospital Campus, Lambeth Palace Road, London SE1 7EH
- Author for correspondence:
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Demirkoprulu N, Cetin M, Bagcivan I, Kaya T, Soydan AS, Karadas B, Cetin A. Comparative relaxant effects of YC-1 and DETA/NO on spontaneous contractions and the levels of cGMP of isolated pregnant rat myometrium. Eur J Pharmacol 2005; 517:240-5. [PMID: 15985262 DOI: 10.1016/j.ejphar.2005.05.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Revised: 05/12/2005] [Accepted: 05/24/2005] [Indexed: 10/25/2022]
Abstract
This study was designed to compare the effects of YC-1 (3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole), a nitric oxide (NO)-independent soluble guanylate cyclase activator, and diethylenetriamine-NONOate (DETA/NO), a NO donor, on spontaneous contractions and the levels of cyclic GMP (cGMP) of myometrial strips isolated from timed-pregnant rats. Myometrial strips were obtained from timed-pregnant Wistar albino rats (n=10) and were mounted in organ baths and tested for changes in isometric tension in response to YC-1 and DETA/NO. We also evaluated the effect of YC-1 and DETA/NO on the levels of cGMP in myometrial strips obtained from timed-pregnant rat uterine horns (n=20). YC-1 (10(-9)-3x10(-5) M) and DETA/NO (10(-7)-10(-4) M) concentration-dependently decreased the amplitude and frequency of spontaneous contractions of myometrial strips isolated from term-pregnant rats. The inhibitions of the amplitude and frequency of spontaneous contractions by YC-1 and DETA/NO were antagonized with methylene-blue (10(-5) M). Antagonistic effect of methylene-blue (10(-5) M) was more on DETA/NO responses than that of YC-1 (P<0.05). In addition, YC-1-stimulated myometrial strips showed more elevation in myometrial cGMP than that of DETA/NO (P<0.05). We demonstrated that YC-1 and DETA/NO induce relaxations in the amplitude and frequency of spontaneous contractions of myometrial strips with different potencies. We also found that YC-1 and DETA/NO-induced relaxations are associated with significant increases in cGMP. These results might suggest that the relaxant effects of YC-1 and DETA/NO on the rat myometrium could be due to the stimulation of the soluble guanylate cyclase and cGMP may play a role for the maintenance of uterine quiescence during pregnancy.
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Affiliation(s)
- Nihal Demirkoprulu
- Department of Obstetrics and Gynecology, Cumhuriyet University School of Medicine, 58140, Sivas, Turkey
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Buxton ILO. Regulation of uterine function: a biochemical conundrum in the regulation of smooth muscle relaxation. Mol Pharmacol 2004; 65:1051-9. [PMID: 15102932 DOI: 10.1124/mol.65.5.1051] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Premature birth accounts for the majority of fetal morbidity and mortality in the developed world and is disproportionately represented in some populations, such as African Americans in the United States. The costs associated with prematurity are staggering in both monetary and human terms. Present therapeutic approaches for the treatment of labor leading to preterm delivery are inadequate and our understanding of the regulation of myometrial smooth muscle contraction-relaxation is incomplete. The ability of nitric oxide to relax smooth muscle has led to an interest in employing nitric oxide-donors in the treatment of preterm labor. Fundamental differences exist, however, in the regulation of uterine smooth muscle relaxation and that of other smooth muscles and constitute a conundrum in our understanding. We review the evidence that nitric oxide-mediated relaxation of myometrial smooth muscle, unlike vascular or gastrointestinal smooth muscle, is independent of global elevation of cyclic guanosine 5'-monophosphate. Applying our current understanding of microdomain signaling and taking clues from genomic studies of pregnancy, we offer a framework in which to view the apparent conundrum and suggest testable hypotheses of uterine relaxation signaling that can explain the mechanistic distinctions. We propose that understanding these mechanistic distinctions in myometrium will reveal molecular targets that are unique and thus may be explored as therapeutic targets in the development of new uterine smooth muscle-specific tocolytics.
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Affiliation(s)
- Iain L O Buxton
- Department of Pharmacology, University of Nevada School of Medicine, Reno, NV 89557, USA.
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Mitchell BF, Olson DM. Prostaglandin endoperoxide H synthase inhibitors and other tocolytics in preterm labour. Prostaglandins Leukot Essent Fatty Acids 2004; 70:167-87. [PMID: 14683691 DOI: 10.1016/j.plefa.2003.04.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Preterm delivery (<37 weeks of gestation) is the major obstetrical complication in developed countries, yet attempts to delay labour and prolong pregnancy have largely been unsuccessful. One of the many reasons it is so difficult to prevent preterm birth is that the nature of preterm labour changes as a function of gestational age, maternal lifestyle factors or infection, to list a few of the reasons. The inhibitors of prostaglandin endoperoxide H synthase (PGHS), known as the Non-steroidal Antiinflammatory Drugs, have been viewed with interest as tocolytics with promising effectiveness under most conditions of preterm labour. Three isoforms of PGHS exist; the first two, PGHS-1 and -2, have been studied for their catalytic activity, X-ray crystallographic structure, and physiological roles in the adult and the foetus. Mixed inhibitors and isoform-specific inhibitors of PGHS have been developed, and their roles in delaying preterm labour are examined and compared to other tocolytics.
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Affiliation(s)
- Bryan F Mitchell
- Department of Obstetrics and Gynaecology, Perinatal Research Centre, CIHR Group in Perinatal Health and Disease, University of Alberta, 220 HMRC, Edmonton, Alberta, Canada T6G2S2
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Cetin A, Kaya T, Demirkoprulu N, Karadas B, Duran B, Cetin M. YC-1, a Nitric Oxide-Independent Activator of Soluble Guanylate Cyclase, Inhibits the Spontaneous Contractions of Isolated Pregnant Rat Myometrium. J Pharmacol Sci 2004; 94:19-24. [PMID: 14745113 DOI: 10.1254/jphs.94.19] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The aim of this study was to investigate the effect of YC-1 (3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole) on spontaneous contractions and levels of cyclic GMP (cGMP) of myometrial strips isolated from pregnant rats. It is a nitric oxide-independent soluble guanylate cyclase activator. Myometrial strips were obtained from eight pregnant Wistar albino rats and were mounted in organ baths for the recording of isometric tensions. We evaluated the effect of increasing concentrations of YC-1 on spontaneous myometrial contractions and on contractions of myometrial smooth muscle pretreated with methylene blue (10(-5) M), tetraethylammonium chloride (TEA) (3 x 10(-4) M), and glibenclamide (10(-6) M). YC-1 (10(-9) - 3 x 10(-5) M) concentration-dependently decreased the amplitude and frequency of spontaneous contractions of myometrial strips. The inhibition of the amplitude and frequency of spontaneous contractions by YC-1 were antagonized with methylene blue (10(-5) M) and TEA (3 x 10(-4) M), but they were not changed by glibenclamide (10(-6) M); however, the antagonistic effect of methylene blue was significantly more than that of TEA (P<0.05). We also evaluated the effect of YC-1 on the levels of cGMP in myometrial strips obtained from pregnant rat uterine horns. YC-1-stimulated myometrial strips showed an excessive elevation in myometrial cGMP that declined slowly during the subsequent washout period. These results show that YC-1 decreases spontaneous contractile activity of myometrial strips isolated from pregnant rat and causes elevation of myometrial cGMP levels in vivo. This effect of YC-1 is significantly reduced by the methylene blue and TEA, suggesting the activation of soluble guanylate cyclase and Ca(2+)-sensitive K(+) channels as the mechanisms of action.
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Affiliation(s)
- Ali Cetin
- Department of Obstetrics and Gynecology, Cumhuriyet University School of Medicine, Sivas, Turkey.
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Tichenor SD, Malmquist NA, Buxton ILO. Dissociation of cGMP accumulation and relaxation in myometrial smooth muscle: effects of S-nitroso-N-acetylpenicillamine and 3-morpholinosyndonimine. Cell Signal 2003; 15:763-72. [PMID: 12781869 DOI: 10.1016/s0898-6568(03)00006-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In guinea pig, primate and man, nitric oxide (NO)-induced regulation of myometrial smooth muscle contraction is distinct from other smooth muscles because cyclic guanosine 3',5'-cyclic monophosphate (cGMP) accumulation is neither necessary nor sufficient to relax the tissue. To further our understanding of the mechanism of action of NO in myometrium, we employed the NO donors, S-nitroso-N-acetylpenicillamine (SNAP), and 3-morpholinosyndonimine (SIN-1) proposed to relax airway smooth muscle by disparate mechanisms involving elevation in intracellular calcium ([Ca(2+)](i)) or cGMP accumulation, respectively. Treatment of guinea pig myometrial smooth muscle with either NO donor at concentrations thought to produce maximal relaxation of smooth muscles resulted in significant elevations in cGMP that were accompanied by phosphorylation of the cGMP-dependent protein kinase substrate vasodilator-stimulated phosphoprotein (VASP), shown here for the first time to be present and phosphorylated in myometrium. Stimulation of myometrial strips with oxytocin (OT, 1 microM) produced an immediate increase in contractile force that persisted in the continued presence of the agonist. Addition of SNAP (100 microM) in the presence of OT relaxed the tissue completely as might be expected of an NO donor. SIN-1 failed to relax the myometrium at any concentration tested up to 300 microM. In Fura-2 loaded myometrial cells prepared from guinea pig, addition of SNAP (100 microM) in the absence of other agonists caused a significant, reproducible elevation of intracellular calcium while SIN-1 employed under the same conditions did not. Our data further support the notion that NO action in myometrium is distinct from that in other smooth muscles and underscores the possibility that discrete regional changes in [Ca(2+)](i), rather than cGMP, signal NO-induced relaxation of the muscle.
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Affiliation(s)
- Stephen D Tichenor
- Department of Pharmacology, University of Nevada School of Medicine, Reno, NV 89557-0270, USA
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Modzelewska B, Kostrzewska A, Sipowicz M, Kleszczewski T, Batra S. Apamin inhibits NO-induced relaxation of the spontaneous contractile activity of the myometrium from non-pregnant women. Reprod Biol Endocrinol 2003; 1:8. [PMID: 12646073 PMCID: PMC151803 DOI: 10.1186/1477-7827-1-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2003] [Accepted: 02/05/2003] [Indexed: 11/10/2022] Open
Abstract
There is now considerable evidence for the involvement of K+ channels in nitric oxide (NO) induced relaxation of smooth muscles including the myometrium. In order to assess whether apamin-sensitive K+ channels play a role in NO - induced relaxation of the human uterus, we have studied the effect of specific blockers of these channels on the relaxation of myometrium from non-pregnant women. In vitro isometric contractions were recorded in uterine tissues from non-pregnant premenopausal women who had undergone hysterectomy. Apamin (10 nM) and scyllatoxin (10 nM) did not alter spontaneous myometrial contractions. However, 15-min pretreatment of the myometrium strips with apamin completely inhibited relaxation caused by diethylamine-nitric oxide (DEA/NO). The pretreatment with scyllatoxin significantly reduced (about 2.6 times) maximum relaxation of the strips induced by DEA/NO (p < 0.05). These results strongly suggest that, beside Ca2+ and voltage dependent charybdotoxin-sensitive (CTX-sensitive) K+ channels, apamin-sensitive K+ channels are also present in the human non-pregnant myometrium. These channels offer an additional target in the development of new tocolytic agents.
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Affiliation(s)
- Beata Modzelewska
- Department of Biophysics, Medical University of Bialystok, ul. Mickiewicza 2A, 15-089 Bialystok, Poland
| | - Anna Kostrzewska
- Department of Biophysics, Medical University of Bialystok, ul. Mickiewicza 2A, 15-089 Bialystok, Poland
| | - Marek Sipowicz
- Department of Pathophysiology of Pregnancy, Medical University of Bialystok, ul. Mickiewicza 2A, 15-089 Bialystok, Poland
| | - Tomasz Kleszczewski
- Department of Biophysics, Medical University of Bialystok, ul. Mickiewicza 2A, 15-089 Bialystok, Poland
| | - Satish Batra
- Department of Obstetrics and Gynaecology, University Hospital, S-221 85 Lund, Sweden
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Carvajal JA, Thompson LP, Weiner CP. Chorion-induced myometrial relaxation is mediated by large-conductance Ca2+-activated K+ channel opening in the guinea pig. Am J Obstet Gynecol 2003; 188:84-91. [PMID: 12548200 DOI: 10.1067/mob.2003.102] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE We previously demonstrated that chorion releases a factor that inhibits both spontaneous and oxytocin-stimulated myometrial contractility. Here, we investigate the mechanism of action of this unidentified substance. STUDY DESIGN Myometrial strips from pregnant guinea pigs were mounted in an organ bath and contractility stimulated with oxytocin. RESULTS Guinea pig chorion produced a time-dependent decrease in oxytocin-induced myometrial contractility. The ability of the chorion to reduce contractility was unaltered by inhibiting chorionic synthesis of either nitric oxide (N [omega]-nitro-L-arginine), carbon monoxide (tin-protoporphyrin), prostaglandins (indomethacin), or the myometrial cyclic guanosine monophosphate pathway (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalime-1-one and Rp-8Br-cGMP). In contrast, iberiotoxin, an inhibitor of large conductance Ca(2+)-activated K(+) channels reduced the quiescent effect of chorion by 40%; in contrast, inhibition of adenosine triphosphate-sensitive (glibenclamide) and voltage-gated K(+) channels (4amynopyridine) had no effect. CONCLUSION Chorion-induced relaxation of oxytocin-stimulated myometrial contraction is, in great part, the product of a paracrine substance that opens myometrial large conductance Ca(2+)-activated K(+) channels.
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Affiliation(s)
- Jorge A Carvajal
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, MD 21201, USA
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Roh CR, Heo JH, Yang SH, Bae DS. Regulation of connexin 43 by nitric oxide in primary uterine myocytes from term pregnant women. Am J Obstet Gynecol 2002; 187:434-40. [PMID: 12193939 DOI: 10.1067/mob.2002.123600] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Our purpose was to test the hypothesis that nitric oxide signals regulate the expression of the gap-junction protein connexin 43 in primary uterine myocytes from pregnant women at term. STUDY DESIGN Northern analysis and immunoblotting were used to determine the expression of connexin 43 in myocytes cultured in the presence of the nitric oxide donors S -nitroso-N -acetyl-penicillamine (SNAP) (100 micromol/L) and (Z)-1-[2-(2-aminoethyl)-N -(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate diethylenetriamine (NOC-18) (100 micromol/L). We also tested the effect of the NO stimulants 8-bromo-cyclic adenosine 3',5'-monophosphate (cAMP) (100 micromol/L) and 8-bromo-cyclic guanosine 3',5'-monophosphate (cGMP) (200 micromol/L), and the nitric oxide synthase inhibitors N -nitro-L-arginine methyl ester (NAME) (100 micromol/L) and L -N (1-iminoethyl)lysine (NIL) (50 micromol/L). RESULTS Nitric oxide and 8-bromo-cAMP reduced the level of connexin 43 expression, and 8-bromo-cGMP had no effect. In contrast, NIL, but not NAME, increased the levels of connexin 43 protein without affecting the level of connexin 43 messenger RNA. With immunoblotting, expression of inducible nitric oxide synthase was not detected in these cells. CONCLUSION Nitric oxide down-regulates the expression of connexin 43 in cultured human myocytes. We speculate that this effect may decrease the efficacy of intermyocyte signaling and thus contribute to uterine quiescence during human pregnancy.
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Affiliation(s)
- Cheong-Rae Roh
- Department of Obstetrics and Gynecology, Samsung Medical Center, and Center for Clinical Research, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Seoul, Korea
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Sand AE, Andersson E, Fried G. Effects of nitric oxide donors and inhibitors of nitric oxide signalling on endothelin- and serotonin-induced contractions in human placental arteries. ACTA PHYSIOLOGICA SCANDINAVICA 2002; 174:217-23. [PMID: 11906320 DOI: 10.1046/j.1365-201x.2002.00939.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In order to explore the role of nitric oxide (NO) in the control of fetoplacental vascular tone in normal pregnancy we have examined the effects of NO donors on uteroplacental arteries pre-contracted with the vasoconstrictor endothelin-1 (ET-1) or serotonin (5-HT). We have furthermore examined the effects of guanylate cyclase inhibitors on the NO-induced relaxation. Segments of placental arteries (n=102) obtained from 39 placentas immediately after delivery were mounted in organ baths and superfused with Krebs-Ringer solution at 37 degrees C. The vessel segments were exposed to drugs for various intervals and the tension was recorded isometrically and registered on a polygraph. Cyclic guanosine monophosphate (cGMP) analysis was performed after extraction of vessel segments using a specific radioimmunoassay. The placental artery segments responded to ET-1 and 5-HT with a dose-dependent vasoconstriction. After pre-contraction with ET-1 (10(-7) M) or 5-HT (10(-6) M), the vessels relaxed in response to the NO donors glyceryltrinitrate (GTN) (10(-6) M) and S-nitroso-N-acetyl-penicillamine (SNAP) (10(-5) M). In the presence of the non-specific guanylate cyclase inhibitor LY 83583 (10(-6) M), the vessels responded with a small contraction. In the presence of the soluble guanylate cyclase (sGC) inhibitor 1H[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) the non-treated vessels responded with a relaxation. 1H[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one gave no obvious relaxation in pre-contracted vessels. Addition of 8-Br-cGMP, the cell-permeant analogue of cGMP, with or without pre-contraction had no effect on the vessels. Cyclic guanosine monophosphate analysis showed that GTN treatment caused an increase in cGMP after 12 min. Our results indicate that NO acts as a vasodilator in placental vessels. The cGMP-dependent mechanisms may be involved in NO-induced relaxation but cGMP-independent mechanisms appear also to be involved.
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Affiliation(s)
- A E Sand
- Department of Women and Child Health, Division of Obstetrics and Gynecology, Karolinska Institute and Hospital, Sweden
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Buxton IL, Kaiser RA, Malmquist NA, Tichenor S. NO-induced relaxation of labouring and non-labouring human myometrium is not mediated by cyclic GMP. Br J Pharmacol 2001; 134:206-14. [PMID: 11522613 PMCID: PMC1572926 DOI: 10.1038/sj.bjp.0704226] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. In myometrial strips from near-term non-labouring human uterus, addition of oxytocin (OT) evoked dose-dependent (10 - 3000 nM) phasic contractions that were antagonized by atosiban (1 microM) and relaxed by addition of the nitric oxide donor S-nitroso L-cysteine (Cys-NO). In near-term labouring myometrium, however, addition of OT was ineffective at raising additional tone. 2. In both labouring and non-labouring tissue, Cys-NO mediated relaxation of spontaneous or OT-induced contractions (IC(50)=1 microM) was unaffected by prior addition of the guanylyl cyclase (GC) inhibitors ODQ (1H-[1,2,4]oxadiazolo[4,3,-alpha]quinoxalin-1-one; 1 microM), or methylene blue (MB; 10 microM). 3. Elevation of intracellular cyclic GMP accompanying 30 microM Cys-NO addition in non-labouring tissue (7.5 fold) or in labouring tissues (2.5 fold) was completely blocked in tissues that had been pre-treated with ODQ or MB. 4. Charybdotoxin (ChTx), iberiotoxin (IbTx) and kaliotoxin (KalTx) all shifted the Cys-NO inhibition curve to the right and reduced the degree of relaxation produced by maximal Cys-NO treatment (100 microM in non-labouring tissue; in labouring tissue, KalTx prevented Cys-NO mediated relaxation in both stimulated and unstimulated tissue. 5. Addition of the NO-donor S-nitroso N-acetyl penicillamine (SNAP) produced a dose-dependent relaxation of pregnant myometrium while 3-morpholinosyndonimine (SIN-1) did not. The failure of SIN-1 to relax OT-induced contractions was not due to a failure of the donor to stimulate myometrial GC. 6. We demonstrate that despite the ability of NO to stimulate myometrial GC in pregnant uterine muscle, relaxations are independent of cyclic GMP action. Effects of K(+)-channel inhibitors suggests that NO-induced relaxation in human uterine smooth muscle may be subserved by direct or indirect activation of one or more calcium-activated K(+)-channels.
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Affiliation(s)
- I L Buxton
- Department of Pharmacology, MS318, University of Nevada School of Medicine, Reno, NV 89557, USA.
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Fulep E, Vedernikov Y, Saade GR, Garfield RE. Contractility of late pregnant rat myometrium is refractory to activation of soluble but not particulate guanylate cyclase. Am J Obstet Gynecol 2001; 185:158-62. [PMID: 11483921 DOI: 10.1067/mob.2001.114871] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Our purpose was to compare the effects of agents activating particulate or soluble guanylate cyclases on the spontaneous contractile activity of the isolated pregnant rat uterus. STUDY DESIGN Uterine rings from midpregnant (14-day) and late pregnant (21-day) rats were suspended in organ chambers to record spontaneous contractile activity. Concentration-response curves were obtained for the following natriuretic peptides: atrial, brain, and C-type; concentration-response curves were also obtained for diethylamine nitric oxide, 3-morpholino-sydnominine, and authentic nitric oxide. RESULTS All 3 natriuretic peptides inhibited spontaneous uterine contractions equally at midgestation and late gestation. The inhibitory effects of the nitric oxide donors diethylamine nitric oxide, 3-morpholino-sydnominine, and authentic nitric oxide were attenuated in uterine tissues from animals in late stages of pregnancy. CONCLUSION Agents activating either soluble or particulate guanylate cyclase inhibit contractions of uterine rings from midgestation rats, whereas the effects of soluble guanylate cyclase are attenuated at late pregnancy. Thus spontaneous uterine contractions are under the control of both soluble and particulate guanylate cyclases; the former is dependent on gestational age but the latter is not.
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Affiliation(s)
- E Fulep
- Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, USA
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Abstract
OBJECTIVES To determine whether human seminal plasma possesses nitric oxide synthase (NOS) activity and whether, if present, this activity correlates with standard semen analysis parameters. Recent studies have demonstrated the presence of NOS in the epithelium of the male reproductive tract and have shown that nitric oxide can influence human sperm function in vitro. METHODS Semen samples were collected from 30 men presenting for an infertility evaluation at our institution. After a standard semen analysis, the semen samples were centrifuged at 10,000g, and the seminal plasma was collected and stored at -20 degrees C for later evaluation of the arginine concentration and calcium-dependent and calcium-independent NOS activity. NOS activity was measured by the conversion of [(3)H]L-arginine to [(3)H]L-citrulline. RESULTS NOS activity was detected in 28 of 30 seminal plasma samples tested. The mean +/- SD calcium-dependent NOS activity was 1.6 +/- 0.8 nmol/min/mL and the mean calcium-independent NOS activity was 1.0 +/- 0.7 nmol/min/mL of the seminal plasma. The mean +/- SD arginine concentration in the seminal plasma was 7.0 +/- 1.9 mM. No significant correlations were found between the NOS activity in the seminal plasma and sperm concentration, sperm motility, or leukocyte concentration. The 2 men without detectable NOS activity in their semen had documented congenital bilateral absence of the vas deferens. CONCLUSIONS The results of this study demonstrate the presence of NOS activity in human semen and support a role of nitric oxide in sperm function in vivo. Our results also suggest that the seminal vesicles may be an important source of NOS activity in semen.
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Affiliation(s)
- A Zini
- James Buchanan Brady Foundation, Department of Urology, New York Presbyterian Hospital-Weill Medical College of Cornell University, New York, New York, USA
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Abstract
The use of nitro-vasodilators for achieving rapid uterine relaxation in the resolution of obstetric emergencies has been documented for nearly 120 years. Glyceryltrinitrate (GTN) is the most commonly used nitro-vasodilator for this purpose, with the presumed mechanism of action being via nitric oxide and cyclic guanosine monophosphate (cGMP) mediated processes. GTN is known to release nitric oxide to effect smooth muscle relaxation and some dose response data is available for its vasodilator activity. Human myometrium is known to synthesize and respond to nitric oxide, with changes in the production of and sensitivity to nitric oxide being subject to the cyclical and gestational state of the uterus. Experimental data on the efficacy of GTN in reliably producing uterine relaxation is conflicting and inconsistent. A total of 32 studies and case reports on the use of GTN in achieving rapid uterine relaxation have appeared in the English language literature. Case reports are subject to reporting bias and prospective randomized controlled trials are not without design flaws. Indications for the use of GTN in achieving rapid uterine relaxation cover the antepartum, intrapartum and postpartum periods. The safety of GTN during obstetric emergencies appears high, with no adverse maternal or neonatal outcomes. To establish the efficacy of GTN in reliably achieving uterine relaxation, well designed randomized controlled trials in labouring women are required.
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Affiliation(s)
- G Caponas
- Nuffield Department of Anaesthetics, John Radcliffe Hospital, Headington, Oxford, United Kingdom.
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Heck DE. *NO, RSNO, ONOO-, NO+, *NOO, NOx--dynamic regulation of oxidant scavenging, nitric oxide stores, and cyclic GMP-independent cell signaling. Antioxid Redox Signal 2001; 3:249-60. [PMID: 11396479 DOI: 10.1089/152308601300185205] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Following its release from nitric oxide synthase, nitric oxide seldom perfuses the cytosol; rather this reactive mediator quickly interacts with available target molecules proximate to its site of release. Within the cell, virtually every component, low-molecular-weight oxidants and reductants, proteins, lipids, sugars, and nucleic acids can be modified by nitrogen oxides thus acting as potential targets for reactive nitrogen oxides. Adducts formed by nitrogen oxides often modulate the cellular activities of the target molecules, and these modified molecules may be differentially metabolized or localized. The formation of nitrogen oxide adducts can be a reversible process, and the reactive nitrogen species released may be specifically oxidized or reduced during the process. Recently, numerous studies have demonstrated that reversible nitration of cellular proteins acts to transduce molecular signals regulating such diverse processes as muscle contraction, neurotransmission, protein metabolism, and apoptosis. The vast numbers of molecules that undergo biologically relevant interactions with nitrogen oxides imply that the cellular concentration of nitrosated and nitrated species may effectively comprise a reserve or cellular store. Potentially, these nitroso reserves function as critical components of the overall redox status of the intracellular environs. Understanding the dynamic regulation of nitric oxide/nitrogen oxides release from these stores is likely to provide clues important in resolving the complex pathophysiology of poorly understood multifactorial disorders, including neurodegeneration, multiorgan failure, cardiomyopathy, and septic shock.
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Affiliation(s)
- D E Heck
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ 08854, USA.
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Affiliation(s)
- D J Crankshaw
- Department of Obstetrics & Gynecology, McMaster University, HSC 3N52, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada.
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Eguchi D, Katusic ZS. Inhibitory effect of valves on endothelium-dependent relaxations to calcium ionophore in canine saphenous vein. Am J Physiol Heart Circ Physiol 2001; 280:H892-8. [PMID: 11158991 DOI: 10.1152/ajpheart.2001.280.2.h892] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study was designed to evaluate endothelium-dependent relaxation to the calcium ionophore A-23187 in isolated canine saphenous veins. Isometric force recordings and cGMP measurements using isolated veins with and without valves were performed. During contractions to U-46619 (3 x 10(-7) M), endothelium-dependent relaxations to A-23187 (10(-9)-10(-6) M) were significantly reduced in rings with valves compared with rings without valves. Endothelial removal abolished A-23187-induced relaxation. Relaxations to forskolin (FK; 10(-8)-10(-5) M) and diethylaminodiazen-1-ium-1,2-dionate; DEA-NONOate, 10(-9)-10(-5) M) were identical in rings with and without valves. In rings without valves, a nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME; 3 x 10(-4) M), and a cyclooxygenase inhibitor, indomethacin (10(-5) M), partially reduced A-23187-induced relaxation. However, in rings with valves, L-NAME had no effect, whereas indomethacin abolished the relaxation to A-23187. A selective soluble guanylate cyclase inhibitor, 1H-[1,2,4]-oxadiazolo [4,3-a]quinoxalin-1-one (ODQ; 3x10(-6) M), had no effect on the relaxation to A-23187 in either group. In contrast, ODQ abolished the A-23187-induced increase in cGMP levels, suggesting that relaxation to nitric oxide released by A-23187 is independent of increases in cGMP. These results demonstrate that endothelium-dependent relaxation to A-23187 is reduced in regions of veins with valves compared with relaxation in the nonvalvular venous wall. Lower production of nitric oxide in endothelial cells of valvular segments appears to be a mechanism responsible for reduced reactivity to A-23187.
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Affiliation(s)
- D Eguchi
- Departments of Anesthesiology and Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota 55905, USA
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Mallis RJ, Thomas JA. Effect of S-nitrosothiols on cellular glutathione and reactive protein sulfhydryls. Arch Biochem Biophys 2000; 383:60-9. [PMID: 11097177 DOI: 10.1006/abbi.2000.2048] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
S-Nitrosothiols may cause many of the biological effects of NO and cellular effects have been attributed to S-nitrosylation of reactive protein sulfhydryls. This report examines the effect of S-nitrosothiols on the low-molecular-weight thiols and protein thiols in NIH/3T3 cells. A low concentration of S-nitrosocysteine increased the cysteine content of the cells, with no evidence of either low-molecular-weight thiol or protein S-nitrosylation. Millimolar amounts of S-nitrosocysteine produced S-nitrosoglutathione (GSNO), cysteinyl glutathione, cysteine, and glutathione disulfide. Large amounts of protein S-nitrosylation and lesser amounts of protein S-glutathiolation and S-cysteylation were also observed. GSNO and S-nitroso-N-acetylpenicillamine (SNAP) were much less effective than S-nitrosocysteine, but a combination of cysteine and GSNO produced S-nitrosocysteine-like effects. In cultured hepatocytes, millimolar S-nitrosocysteine was significantly less effective since the cells contained three times more glutathione than NIH/3T3 cells. Results suggest that S-nitrosocysteine enters cells intact, and low concentrations do not significantly increase cellular pools of S-nitrosothiol or S-nitrosylated protein. Millimolar concentrations of S-nitrosocysteine generate S-nitrosylated, S-glutathiolated, and S-cysteylated proteins, as well as a variety of low-molecular-weight disulfides and S-nitrosothiols.
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Affiliation(s)
- R J Mallis
- Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames 50011, USA
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Sawada M, Ichinose M, Anraku M. Inhibition of the glutamate-induced K(+) current in identified Onchidium neurons by nitric oxide donors. J Neurosci Res 2000; 60:642-8. [PMID: 10820435 DOI: 10.1002/(sici)1097-4547(20000601)60:5<642::aid-jnr9>3.0.co;2-#] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Nitric oxide (NO) acts as a neurotransmitter and neuromodulator in the nervous system of many vertebrates and invertebrates. The effects of extracellularly applied sodium nitroprusside (SNP) and diethylamine NO (C(2)H(5))(2)N[N(O)NO]-Na(+) (DEA/NO), NO donors, on a glutamate (Glu)-induced K(+) current in identified Onchidium neurons were investigated using voltage clamp and pressure ejection techniques. Bath-applied SNP (10 microM) and DEA/NO (5-10 microM) reduced the Glu-induced K(+) current without affecting the resting membrane conductance and holding current. The Glu-induced K(+) current also was inhibited by the focal application of SNP to the neuron somata. The suppressing effects of NO donors were concentration-dependent and completely reversible. Pretreatment with hemoglobin (50 microM), a nitric oxide scavenger, and 1H-[1,2, 4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 1 microM), a specific inhibitor of NO-stimulated guanylate cyclase, decreased the SNP-induced inhibition of the Glu-induced current. Bath-applied 50 microM 3-isobutyl-1-methylxanthine (IBMX), a nonspecific phosphodiesterase inhibitor, or intracellular injection of 1 mM guanosine 3',5'-cyclic monophosphate (cGMP) inhibited the Glu-induced current, mimicking the effect of NO donors. These results demonstrate that SNP and DEA/NO inhibit the Glu-induced K(+) current and that the mechanism of NO inhibition of the Glu-induced current involves cGMP-dependent protein kinase.
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Affiliation(s)
- M Sawada
- Department of Physiology, Shimane Medical University, Izumo, Japan.
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