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Salami SA, Salahdeen HM, Obafemi AE, Murtala BA. Uterine contractile activity and fetal outcome in rats treated with vitamin C during late gestational variable stress exposure. JOURNAL OF COMPLEMENTARY & INTEGRATIVE MEDICINE 2021; 18:745-751. [PMID: 33964203 DOI: 10.1515/jcim-2020-0276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/11/2020] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Stress responses vary throughout pregnancy and impact of late gestational variable stress (LGVS) with vitamin C supplementation on uterine contractility is barely explored. This study investigates fetal weight outcome and in-vitro uterine contractile responses to pharmacological agents during LGVS exposure. METHODS Twenty four nulliparous pregnant rats were divided into four groups of six. During gestation days 10-19, groups 1 & 2 received normal saline and vitamin C (10 mg/kg) respectively. Groups 3 and 4 were exposed to stress (sleep deprivation, predator exposure, immobility, rapid cage changes, noise, and foreign object) with group 4 concurrently supplemented with vitamin C (10 mg/kg). Serum cortisol, oxidative bio-markers, fetal weights and in-vitro contractile responses of excised uterine tissue to acetylcholine (Ach), oxytocin, calcium chloride (CaCl2), potassium chloride (KCl), diclofenac, and magnesium ions were determined. RESULTS Malondialdehyde activity and cortisol were significantly increased in variable stress only exposed group when compared with control and vitamin C supplemented groups. Fetal body weights, superoxide dismutase and catalase activity were significantly reduced in variable stress only exposed group. Significantly impaired contractile responses to Ach, CaCl2 & KCl in variable stress only exposed group were modulated in vitamin C supplemented groups. Impaired contractile response to oxytocin was however not reversed. Relaxation responses to diclofenac and magnesium ions were statistically unaltered across groups. CONCLUSIONS Impaired fetal weights and uterine contractile activity to Ach, CaCl2 and KCl during LGVS was modulated by vitamin C supplementation. Impaired oxytocin contractile activity was however unreversed.
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Affiliation(s)
- Shakiru A Salami
- Department of Physiology, Lagos State University College of Medicine, Ikeja, Lagos State, Nigeria
| | - Hussein M Salahdeen
- Department of Physiology, Lagos State University College of Medicine, Ikeja, Lagos State, Nigeria
| | - Abidemi E Obafemi
- Department of Physiology, Lagos State University College of Medicine, Ikeja, Lagos State, Nigeria
| | - Babatunde A Murtala
- Department of Physiology, Lagos State University College of Medicine, Ikeja, Lagos State, Nigeria
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Calcium signaling cascades differentially regulate PGF 2α-induced myometrial contractions in water buffaloes (Bubalus bubalis). Naunyn Schmiedebergs Arch Pharmacol 2021; 394:1651-1664. [PMID: 33884445 DOI: 10.1007/s00210-021-02084-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 03/30/2021] [Indexed: 10/21/2022]
Abstract
This study unravels the differential involvement of calcium signaling pathway(s) in PGF2α-induced contractions in myometrium of nonpregnant (NP) and pregnant buffaloes. Compared to the myometrium of pregnant animals, myometrium of NP buffaloes was more sensitive to PGF2α as manifested by changes in mean integral tension (MIT) and tonicity. In the presence of nifedipine, myometrial contraction to PGF2α was significantly attenuated in both NP and pregnant uteri; however, mibefradil and NNC 55-0396 produced inhibitory effects only in uterus of pregnant animals, thus suggesting the role of extracellular Ca2+ influx through nifedipine-sensitive L-type Ca2+-channels both in NP and pregnant, but T-type Ca2+ channels seem to play a role only during pregnancy. Entry of extracellular Ca2+ is triggered by enhanced functional involvement of Pyr3-sensitive TRPC3 channels and Rho-kinase pathways as evidenced by a significant rightward shift of the concentration-response curve of PGF2α in the presence of Pyr3 and Y-27632 in NP myometrium. But significant down-expressions of TRPC3 and Rho-A proteins during pregnancy apparently facilitate uterine quiescence. In the presence of Ca2+-free solution and cyclopiazonic acid (SERCA blocker), feeble contraction to PGF2α was observed in both NP and pregnant myometrium which suggests minor role of intracellular source of Ca2+ in mediating PGF2α-induced contractions in these tissues.
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Malik M, Roh M, England SK. Uterine contractions in rodent models and humans. Acta Physiol (Oxf) 2021; 231:e13607. [PMID: 33337577 PMCID: PMC8047897 DOI: 10.1111/apha.13607] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 12/07/2020] [Accepted: 12/11/2020] [Indexed: 12/18/2022]
Abstract
Aberrant uterine contractions can lead to preterm birth and other labour complications and are a significant cause of maternal morbidity and mortality. To investigate the mechanisms underlying dysfunctional uterine contractions, researchers have used experimentally tractable small animal models. However, biological differences between humans and rodents change how researchers select their animal model and interpret their results. Here, we provide a general review of studies of uterine excitation and contractions in mice, rats, guinea pigs, and humans, in an effort to introduce new researchers to the field and help in the design and interpretation of experiments in rodent models.
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Affiliation(s)
- Manasi Malik
- Center for Reproductive Health Sciences Department of Obstetrics and Gynecology Washington University School of Medicine St. Louis MO USA
| | - Michelle Roh
- Center for Reproductive Health Sciences Department of Obstetrics and Gynecology Washington University School of Medicine St. Louis MO USA
| | - Sarah K. England
- Center for Reproductive Health Sciences Department of Obstetrics and Gynecology Washington University School of Medicine St. Louis MO USA
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Sadraei H, Sajjadi SE, Asghari G, Khalili M. Effect of Matricaria chamomilla hydro-alcoholic and flavonoids rich extracts on rat isolated uterus. JOURNAL OF HERBMED PHARMACOLOGY 2020. [DOI: 10.15171/jhp.2020.05] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Introduction: Pharmacological studies confirm antispasmodic activities of chamomile (Matricaria chamomilla) extract on intestinal smooth muscles and it has been suggested that chamomile increases uterus tone, but so far there is no scientific studies which support this assumption. Therefore, this study was designed to determine spasmodic and spasmolytic activities of M. chamomilla extracts on rat isolated uterus. Methods: Hydro-alcoholic extract of M. chamomilla was prepared by maceration technique. Flavonoids rich extract was prepared by liquid in liquid extraction technique. The spasmodic effects of the extracts were assessed on spontaneously contracting rat uterus. The myorelaxant effect of M. chamomilla extracts was validated on isolated uterus contractions induced by KCl, acetylcholine (ACh), electrical field stimulation (EFS) and oxytocin. Results: Hydro-alcoholic extract of M. chamomilla (0.8 and 1.6 mg/mL) enhanced spontaneous movement of rat isolated uterus smooth muscle suspended in an organ bath. On the other hand, flavonoids rich fraction only diminished uterus contractile activities. Flavonoids rich extract of the plant at bath concentration ranges of 40 μg/mL to 400 μg/mL attenuated uterus response to ACh, KCl, EFS and oxytocin. The hydro-alcoholic extract of M. chamomilla at higher concentration ranges (250 μg/mL to 1.5 mg/mL) inhibited uterus contractions induced by the above spasmogens. Conclusion: The present study confirms both spasmodic and spasmolytic activities M. chamomilla hydro-alcoholic extract. Therefore, medicinal use of the crude extract of M. chamomilla may initiate uterus contraction which could increase risk of spontaneous miscarriage or premature parturition.
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Affiliation(s)
- Hassan Sadraei
- Department of Pharmacology and Toxicology, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Seyed Ebrahim Sajjadi
- Department of Pharmacognosy and Isfahan Pharmaceutical Sciences Research Center, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Gholamreza Asghari
- Department of Pharmacognosy and Isfahan Pharmaceutical Sciences Research Center, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Majid Khalili
- Department of Pharmacology and Toxicology, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
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Ferreira JJ, Butler A, Stewart R, Gonzalez-Cota AL, Lybaert P, Amazu C, Reinl EL, Wakle-Prabagaran M, Salkoff L, England SK, Santi CM. Oxytocin can regulate myometrial smooth muscle excitability by inhibiting the Na + -activated K + channel, Slo2.1. J Physiol 2018; 597:137-149. [PMID: 30334255 DOI: 10.1113/jp276806] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/17/2018] [Indexed: 01/05/2023] Open
Abstract
KEY POINTS At the end of pregnancy, the uterus transitions from a quiescent state to a highly contractile state. This transition requires that the uterine (myometrial) smooth muscle cells increase their excitability, although how this occurs is not fully understood. We identified SLO2.1, a potassium channel previously unknown in uterine smooth muscle, as a potential significant contributor to the electrical excitability of myometrial smooth muscle cells. We found that activity of the SLO2.1 channel is negatively regulated by oxytocin via Gαq-protein-coupled receptor activation of protein kinase C. This results in depolarization of the uterine smooth muscle cells and calcium entry, which may contribute to uterine contraction. These findings provide novel insights into a previously unknown mechanism by which oxytocin may act to modulate myometrial smooth muscle cell excitability. Our findings also reveal a new potential pharmacological target for modulating uterine excitability. ABSTRACT During pregnancy, the uterus transitions from a quiescent state to a more excitable contractile state. This is considered to be at least partly a result of changes in the myometrial smooth muscle cell (MSMC) resting membrane potential. However, the ion channels controlling the myometrial resting membrane potential and the mechanism of transition to a more excitable state have not been fully clarified. In the present study, we show that the sodium-activated, high-conductance, potassium leak channel, SLO2.1, is expressed and active at the resting membrane potential in MSMCs. Additionally, we report that SLO2.1 is inhibited by oxytocin binding to the oxytocin receptor. Inhibition of SLO2.1 leads to membrane depolarization and activation of voltage-dependent calcium channels, resulting in calcium influx. The results of the present study reveal that oxytocin may modulate MSMC electrical activity by inhibiting SLO2.1 potassium channels.
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Affiliation(s)
- Juan J Ferreira
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA
| | - Alice Butler
- Washington University School of Medicine, Department of Neuroscience, St Louis, MO, USA
| | - Richard Stewart
- Washington University School of Medicine, Department of Neuroscience, St Louis, MO, USA
| | - Ana Laura Gonzalez-Cota
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA
| | - Pascale Lybaert
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA.,Present address: Laboratoire de Physiologie et Pharmacologie (LAPP), Faculté de Médecine, Université Libre de Bruxelles, Bruxelles, Belgium
| | - Chinwendu Amazu
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA
| | - Erin L Reinl
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA.,Present address: Pharmacology Department, School of Medicine, University of Maryland, Baltimore, MD, USA
| | - Monali Wakle-Prabagaran
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA
| | - Lawrence Salkoff
- Washington University School of Medicine, Department of Neuroscience, St Louis, MO, USA
| | - Sarah K England
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA
| | - Celia M Santi
- Washington University School of Medicine, Department of Obstetrics and Gynecology, St Louis, MO, USA.,Washington University School of Medicine, Department of Neuroscience, St Louis, MO, USA
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Young RC. The uterine pacemaker of labor. Best Pract Res Clin Obstet Gynaecol 2018; 52:68-87. [PMID: 29866432 DOI: 10.1016/j.bpobgyn.2018.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 04/10/2018] [Indexed: 10/17/2022]
Abstract
The laboring uterus is generally thought to initiate contractions much similar to the heart, with a single, dedicated pacemaker. Research on human and animal models over decades has failed to identify such pacemaker. On the contrary, data indicate that instead of being fixed at a site similar to the sinoatrial node of the heart, the initiation site for each uterine contraction changes during time, often with each contraction. The enigmatic uterine "pacemaker" does not seem to fit the standard definition of what a pacemaker should be. The uterine pacemaker must also mesh with the primary physiological function of the uterus - to generate intrauterine pressure. This requires that most areas of the uterine wall contract in a coordinated, or synchronized, manner for each contraction of labor. It is not clear whether the primary mechanism of the uterine pacemaker is a slow-wave generator or an impulse generator. Slow waves in the gut initiate localized smooth muscle contractions. Because the uterus and the gut have somewhat similar cellular and tissue structure, it is reasonable to consider if uterine contractions are paced by a similar mechanism. Unfortunately, there is no convincing experimental verification of uterine slow waves. Similarly, there is no convincing evidence of a cellular mechanism for impulse generation. The uterus appears to have multiple widely dispersed mechanically sensitive functional pacemakers. It is possible that the coordination of organ-level function occurs through intrauterine pressure, thus creating wall stress followed by activation of many mechanosensitive electrogenic pacemakers.
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Kazaryan KV, Piliposyan TA, Unanyan NG, Mkrtchyan EK. The role of the ovarian horn locus in regulation of spontaneous electric activity of myometrial rhythmogenic areas. J EVOL BIOCHEM PHYS+ 2017. [DOI: 10.1134/s0022093017050076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Sharma A, Nakade UP, Jaitley P, Sharma V, Choudhury S, Garg SK. WITHDRAWN: Differential involvement of L- and T-type Ca 2+ channels, store-operated calcium channel (TRPC) and Rho-kinase signaling pathway(s) in PGF 2α-induced contractions in myometrium of non-pregnant and pregnant buffaloes (Bubalus bubalis). Prostaglandins Other Lipid Mediat 2017:S1098-8823(17)30021-7. [PMID: 28916261 DOI: 10.1016/j.prostaglandins.2017.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Revised: 09/05/2017] [Accepted: 09/06/2017] [Indexed: 11/30/2022]
Abstract
This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.
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Affiliation(s)
- Abhishek Sharma
- Experimental Pharmacology Laboratory, Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura 281001, India
| | - Udayraj P Nakade
- Experimental Pharmacology Laboratory, Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura 281001, India
| | - Pooja Jaitley
- Experimental Pharmacology Laboratory, Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura 281001, India
| | - Vipin Sharma
- Experimental Pharmacology Laboratory, Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura 281001, India
| | - Soumen Choudhury
- Experimental Pharmacology Laboratory, Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura 281001, India
| | - Satish Kumar Garg
- Experimental Pharmacology Laboratory, Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura 281001, India.
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Functional involvement of protein kinase C, Rho-kinase and TRPC3 decreases while PLC increases with advancement of pregnancy in mediating oxytocin-induced myometrial contractions in water buffaloes ( Bubalus bubalis ). Theriogenology 2017; 92:176-189. [DOI: 10.1016/j.theriogenology.2016.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 12/06/2016] [Accepted: 12/06/2016] [Indexed: 11/20/2022]
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Sharma A, Nakade UP, Choudhury S, Yadav RS, Garg SK. Extra and intracellular calcium signaling pathway(s) differentially regulate histamine-induced myometrial contractions during early and mid-pregnancy stages in buffaloes (Bubalus bubalis). Anim Reprod Sci 2017; 179:10-19. [PMID: 28228338 DOI: 10.1016/j.anireprosci.2017.01.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 01/18/2017] [Accepted: 01/25/2017] [Indexed: 10/20/2022]
Abstract
This study examines the differential role of calcium signaling pathway(s) in histamine-induced uterotonic action during early and mid-pregnancy stages in buffaloes. Compared to mid pregnancy, tonic contraction, amplitude and mean-integral tension were significantly increased by histamine to produce myometrial contraction during early pregnancy with small effects on phasic contraction and frequency. Although uterotonic action of histamine during both stages of pregnancy is sensitive to nifedipine (a L-type Ca2+ channels blocker) and NNC55-0396 (T-type Ca2+ channels blocker), the role of extracellular calcium seems to be more significant during mid-pregnancy as in this stage histamine produced only 9.38±0.96% contraction in Ca2+ free-RLS compared to 21.60±1.45% in uteri of early pregnancy stage. Intracellular calcium plays major role in histamine-induced myometrial contraction during early pregnancy as compared to mid pregnancy, as in the presence of cyclopiazonic acid (CPA) Ca2+-free RLS, histamine produced significantly higher contraction in myometrial strips of early-pregancy in comparison to mid-pregnancy (10.59±1.58% and 3.13±0.46%, respectively). In the presence of U-73122, the DRC of histamine was significantly shifted towards right with decrease in maximal effect (Emax) only in early pregnancy suggesting the predominant role of phospholipase-C (PL-C) in this stage of pregnancy.
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Affiliation(s)
- Abhishek Sharma
- Experimental Pharmacology Laboratory, Department of Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, UP Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan, Mathura, U.P., 281 001, India
| | - Udayraj P Nakade
- Experimental Pharmacology Laboratory, Department of Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, UP Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan, Mathura, U.P., 281 001, India
| | - Soumen Choudhury
- Experimental Pharmacology Laboratory, Department of Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, UP Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan, Mathura, U.P., 281 001, India
| | - Rajkumar Singh Yadav
- Experimental Pharmacology Laboratory, Department of Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, UP Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan, Mathura, U.P., 281 001, India
| | - Satish Kumar Garg
- Experimental Pharmacology Laboratory, Department of Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, UP Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan, Mathura, U.P., 281 001, India.
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Wray S, Burdyga T, Noble D, Noble K, Borysova L, Arrowsmith S. Progress in understanding electro-mechanical signalling in the myometrium. Acta Physiol (Oxf) 2015; 213:417-31. [PMID: 25439280 DOI: 10.1111/apha.12431] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 11/11/2014] [Accepted: 11/17/2014] [Indexed: 11/30/2022]
Abstract
In this review, we give a state-of-the-art account of uterine contractility, focussing on excitation-contraction (electro-mechanical) coupling (ECC). This will show how electrophysiological data and intracellular calcium measurements can be related to more modern techniques such as confocal microscopy and molecular biology, to advance our understanding of mechanical output and its modulation in the smooth muscle of the uterus, the myometrium. This new knowledge and understanding, for example concerning the role of the sarcoplasmic reticulum (SR), or stretch-activated K channels, when linked to biochemical and molecular pathways, provides a clearer and better informed basis for the development of new drugs and targets. These are urgently needed to combat dysfunctions in excitation-contraction coupling that are clinically challenging, such as preterm labour, slow to progress labours and post-partum haemorrhage. It remains the case that scientific progress still needs to be made in areas such as pacemaking and understanding interactions between the uterine environment and ion channel activity.
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Affiliation(s)
- S. Wray
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool Women's Hospital; Liverpool UK
| | - T. Burdyga
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool Women's Hospital; Liverpool UK
| | - D. Noble
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool Women's Hospital; Liverpool UK
| | - K. Noble
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool Women's Hospital; Liverpool UK
| | - L. Borysova
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool Women's Hospital; Liverpool UK
| | - S. Arrowsmith
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool Women's Hospital; Liverpool UK
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Gravina FS, van Helden DF, Kerr KP, de Oliveira RB, Jobling P. Phasic contractions of the mouse vagina and cervix at different phases of the estrus cycle and during late pregnancy. PLoS One 2014; 9:e111307. [PMID: 25337931 PMCID: PMC4206458 DOI: 10.1371/journal.pone.0111307] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 09/30/2014] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND/AIMS The pacemaker mechanisms activating phasic contractions of vaginal and cervical smooth muscle remain poorly understood. Here, we investigate properties of pacemaking in vaginal and cervical tissues by determining whether: 1) functional pacemaking is dependent on the phase of the estrus cycle or pregnancy; 2) pacemaking involves Ca2+ release from sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) -dependent intracellular Ca2+ stores; and 3) c-Kit and/or vimentin immunoreactive ICs have a role in pacemaking. METHODOLOGY/PRINCIPAL FINDINGS Vaginal and cervical contractions were measured in vitro, as was the distribution of c-Kit and vimentin positive interstitial cells (ICs). Cervical smooth muscle was spontaneously active in estrus and metestrus but quiescent during proestrus and diestrus. Vaginal smooth muscle was normally quiescent but exhibited phasic contractions in the presence of oxytocin or the K+ channel blocker tetraethylammonium (TEA) chloride. Spontaneous contractions in the cervix and TEA-induced phasic contractions in the vagina persisted in the presence of cyclopiazonic acid (CPA), a blocker of the SERCA that refills intracellular SR Ca2+ stores, but were inhibited in low Ca2+ solution or in the presence of nifedipine, an inhibitor of L-type Ca2+channels. ICs were found in small numbers in the mouse cervix but not in the vagina. CONCLUSIONS/SIGNIFICANCE Cervical smooth muscle strips taken from mice in estrus, metestrus or late pregnancy were generally spontaneously active. Vaginal smooth muscle strips were normally quiescent but could be induced to exhibit phasic contractions independent on phase of the estrus cycle or late pregnancy. Spontaneous cervical or TEA-induced vaginal phasic contractions were not mediated by ICs or intracellular Ca2+ stores. Given that vaginal smooth muscle is normally quiescent then it is likely that increases in hormones such as oxytocin, as might occur through sexual stimulation, enhance the effectiveness of such pacemaking until phasic contractile activity emerges.
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Affiliation(s)
- Fernanda S. Gravina
- School of Biomedical Sciences & Pharmacy, Faculty of Health & Medicine, The University of Newcastle, Callaghan, NSW, Australia
| | - Dirk F. van Helden
- School of Biomedical Sciences & Pharmacy, Faculty of Health & Medicine, The University of Newcastle, Callaghan, NSW, Australia
| | - Karen P. Kerr
- School of Biomedical Sciences & Pharmacy, Faculty of Health & Medicine, The University of Newcastle, Callaghan, NSW, Australia
| | - Ramatis B. de Oliveira
- School of Biomedical Sciences & Pharmacy, Faculty of Health & Medicine, The University of Newcastle, Callaghan, NSW, Australia
| | - Phillip Jobling
- School of Biomedical Sciences & Pharmacy, Faculty of Health & Medicine, The University of Newcastle, Callaghan, NSW, Australia
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Store-operated Ca²⁺ entry and depolarization explain the anomalous behaviour of myometrial SR: effects of SERCA inhibition on electrical activity, Ca²⁺ and force. Cell Calcium 2014; 56:188-94. [PMID: 25084623 PMCID: PMC4169181 DOI: 10.1016/j.ceca.2014.07.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 07/03/2014] [Accepted: 07/09/2014] [Indexed: 11/23/2022]
Abstract
SERCA pump inhibition by CPA caused membrane depolarization, activation of action potentials, Ca2+ spikes and force. Depletion of Ca2+ store by agonists leads to membrane depolarization and activation of electrical and mechanical activity. Ca2+ release/Ca2+ entry coupling is playing a key role in control of spontaneous electrical and mechanical activity in rat pregnant myometrium.
In the myometrium SR Ca2+ depletion promotes an increase in force but unlike several other smooth muscles, there is no Ca2+ sparks-STOCs coupling mechanism to explain this. Given the importance of the control of contractility for successful parturition, we have examined, in pregnant rat myometrium, the effects of SR Ca2+-ATPase (SERCA) inhibition on the temporal relationship between action potentials, Ca2+ transients and force. Simultaneous recording of electrical activity, calcium and force showed that SERCA inhibition, by cyclopiazonic acid (CPA 20 μM), caused time-dependent changes in excitability, most noticeably depolarization and elevations of baseline [Ca2+]i and force. At the onset of these changes there was a prolongation of the bursts of action potentials and a corresponding series of Ca2+ spikes, which increased the amplitude and duration of contractions. As the rise of baseline Ca2+ and depolarization continued a point was reached when electrical and Ca2+ spikes and phasic contractions ceased, and a maintained, tonic force and Ca2+ was produced. Lanthanum, a non-selective blocker of store-operated Ca2+ entry, but not the L-type Ca2+ channel blocker nifedipine (1–10 μM), could abolish the maintained force and calcium. Application of the agonist, carbachol, produced similar effects to CPA, i.e. depolarization, elevation of force and calcium. A brief, high concentration of carbachol, to cause SR Ca2+ depletion without eliciting receptor-operated channel opening, also produced these results. The data obtained suggest that in pregnant rats SR Ca2+ release is coupled to marked Ca2+ entry, via store operated Ca2+ channels, leading to depolarization and enhanced electrical and mechanical activity.
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Sharma A, Choudhury S, Nakade UP, Yadav RS, Garg SK. Calcium influx and release mechanism(s) in histamine-induced myometrial contraction in buffaloes. Anim Reprod Sci 2014; 146:157-64. [PMID: 24631173 DOI: 10.1016/j.anireprosci.2014.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 02/02/2014] [Accepted: 02/15/2014] [Indexed: 01/10/2023]
Abstract
The present study was undertaken to characterize the presence of histamine H1R using molecular biology tools and unravel the influx and release mechanism(s) involved in calcium signalling cascades in histamine-induced myometrial contraction in buffaloes. The presence of H1R mRNA transcript and immunoreactive membrane protein in buffalo myometrium was confirmed by RT-PCR and Western blot analysis. Further, histamine produced concentration-dependent (1nM-10μM) contraction in buffalo myometrium with a potency of 7.13±0.11. When myometrial strips were pre-incubated either with Ca(2+) free solution or with nifedipine, a L-type Ca(2+) channel blocker, dose response curve (DRC) of histamine was significantly (P<0.05) shifted towards right with decline in maximal contraction (Emax). Reduction in Emax of histamine in the presence of nifedipine (55.75±3.10%) was significantly (P<0.001) greater than that in the presence of ruthenium red (93.61±3.43%), a blocker of IP3-gated and RyR-sensitive Ca(2+) channels. Moreover, histamine produced only 26.87±1.99% of the maximum contraction in the presence of both nifedipine and CPA (blocker of sarco-endoplasmic reticulum Ca(2+)-ATPase). Interestingly, following concurrent exposure to U-73122 (a PL-C inhibitor) and nifedipine, the DRC of histamine was significantly (P<0.05) shifted towards left with increase in maximal contraction (126.30±3.36%). Our findings in buffalo uterus thus suggest that influx of extracellular calcium plays a major role in histamine-induced myometrial contraction, while release of intracellular calcium through calcium-release channels of sarcoplasmic reticulum has a minor role. A possible involvement of non-selective cation channels in histamine-induced myometrial contraction cannot be ruled out, and therefore requires further investigations.
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Affiliation(s)
- Abhishek Sharma
- Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan, Mathura 281001, India
| | - Soumen Choudhury
- Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan, Mathura 281001, India
| | - Udayraj P Nakade
- Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan, Mathura 281001, India
| | - Rajkumar Singh Yadav
- Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan, Mathura 281001, India
| | - Satish Kumar Garg
- Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan, Mathura 281001, India.
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16
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Gravina FS, Parkington HC, Kerr KP, de Oliveira RB, Jobling P, Coleman HA, Sandow SL, Davies MM, Imtiaz MS, van Helden DF. Role of mitochondria in contraction and pacemaking in the mouse uterus. Br J Pharmacol 2011; 161:1375-90. [PMID: 20942856 DOI: 10.1111/j.1476-5381.2010.00949.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND AND PURPOSE Uterine spontaneous contraction and pacemaking are poorly understood. This study investigates the role of the mitochondrial Ca(2+) store in uterine activity. EXPERIMENTAL APPROACH We investigated the effects of mitochondrial and sarco-endoplasmic reticulum (SER) inhibitors on contraction, membrane potential (Vm) and cytosolic Ca(2+) concentration ([Ca(2+) ](c) ) in longitudinal smooth muscle of the mouse uterus. KEY RESULTS The mitochondrial agents rotenone, carbonylcyanide-3-chlorophenylhydrazone (CCCP), 7-chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1-benzothiazepin-2(3H)-one (CGP37157) and kaempferol decreased the force of contractions. The ATP synthase inhibitor oligomycin had no significant effect. The effects of these agents were compared with those of SER inhibitors cyclopiazonic acid (CPA), 2-amino ethoxyphenylborate (2-APB) and caffeine. All agents, except CPA and oligomycin, decreased contractile force. CPA and CCCP transiently increased contraction frequency, which returned to control levels, whereas rotenone, CGP37157, kaempferol and 2-APB decreased frequency and caffeine had no significant effect. Application of the mitochondrial agents when CPA functionally inhibited stores did not change contraction frequency but, with the exception of kaempferol, decreased force. CCCP caused depolarization and maintained increase in [Ca(2+) ](c) or depolarization/transient hyperpolarization and transient increase in [Ca(2+) ](c) for oestrus and di-oestrus tissues respectively. Rotenone caused hyperpolarization and maintained increase in [Ca(2+) ](c) . CGP37157 and kaempferol caused hyperpolarization but no measurable change in [Ca(2+) ](c) . Application of a range of K(+) channel blockers indicated a role of Ca(2+) -activated K(+) (K(Ca) ) channels in the CCCP- and CGP37157-induced actions. CONCLUSIONS AND IMPLICATIONS Mitochondria have a modulatory role on uterine contractions, with mitochondrial inhibition reducing contraction amplitude and pacemaker frequency by changes in Vm, [Ca(2+) ](c) and/or Ca(2+) influx.
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Affiliation(s)
- F S Gravina
- School of Biomedical Sciences, University of Newcastle, Callaghan, NSW, Australia
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17
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Dixon RE, Britton FC, Baker SA, Hennig GW, Rollings CM, Sanders KM, Ward SM. Electrical slow waves in the mouse oviduct are dependent on extracellular and intracellular calcium sources. Am J Physiol Cell Physiol 2011; 301:C1458-69. [PMID: 21881003 DOI: 10.1152/ajpcell.00293.2011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Spontaneous contractions of the myosalpinx are critical for oocyte transport along the oviduct. Slow waves, the electrical events that underlie myosalpinx contractions, are generated by a specialized network of pacemaker cells called oviduct interstitial cells of Cajal (ICC-OVI). The ionic basis of oviduct pacemaker activity is unknown. Intracellular recordings and Ca(2+) imaging were performed to examine the role of extracellular and intracellular Ca(2+) sources in slow wave generation. RT-PCR was performed to determine the transcriptional expression of Ca(2+) channels. Molecular studies revealed most isoforms of L- and T-type calcium channels (Cav1.2,1.3,1.4,3.1,3.2,3.3) were expressed in myosalpinx. Reduction of extracellular Ca(2+) concentration ([Ca(2+)](o)) resulted in the abolition of slow waves and myosalpinx contractions without significantly affecting resting membrane potential (RMP). Spontaneous Ca(2+) waves spread through ICC-OVI cells at a similar frequency to slow waves and were inhibited by reduced [Ca(2+)](o). Nifedipine depolarized RMP and inhibited slow waves; however, pacemaker activity returned when the membrane was repolarized with reduced extracellular K(+) concentration ([K(+)](o)). Ni(2+) also depolarized RMP but failed to block slow waves. The importance of ryanodine and inositol 1,4,5 trisphosphate-sensitive stores were examined using ryanodine, tetracaine, caffeine, and 2-aminoethyl diphenylborinate. Results suggest that although both stores are involved in regulation of slow wave frequency, neither are exclusively essential. The sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) pump inhibitor cyclopiazonic acid inhibited pacemaker activity and Ca(2+) waves suggesting that a functional SERCA pump is necessary for pacemaker activity. In conclusion, results from this study suggest that slow wave generation in the oviduct is voltage dependent, occurs in a membrane potential window, and is dependent on extracellular calcium and functional SERCA pumps.
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Affiliation(s)
- Rose Ellen Dixon
- Dept. of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
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18
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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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19
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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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20
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Lee SE, Ahn DS, Lee YH. Role of T-type Ca Channels in the Spontaneous Phasic Contraction of Pregnant Rat Uterine Smooth Muscle. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2009; 13:241-9. [PMID: 19885043 DOI: 10.4196/kjpp.2009.13.3.241] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 06/04/2009] [Accepted: 06/19/2009] [Indexed: 11/15/2022]
Abstract
Although extracellular Ca(2+) entry through the voltage-dependent Ca(2+) channels plays an important role in the spontaneous phasic contractions of the pregnant rat myometrium, the role of the T-type Ca(2+) channels has yet to be fully identified. The aim of this study was to investigate the role of the T-type Ca(2+) channel in the spontaneous phasic contractions of the rat myometrium. Spontaneous phasic contractions and [Ca(2+)](i) were measured simultaneously in the longitudinal strips of female Sprague-Dawley rats late in their pregnancy (on day 18~20 of gestation: term=22 days). The expression of T-type Ca(2+) channel mRNAs or protein levels was measured. Cumulative addition of low concentrations (<1 microM) of nifedipine, a L-type Ca(2+) channel blocker, produced a decrease in the amplitude of the spontaneous Ca(2+) transients and contractions with no significant change in frequency. The mRNAs and proteins encoding two subunits (alpha1G, alpha1H) of the T-type Ca(2+) channels were expressed in longitudinal muscle layer of rat myometrium. Cumulative addition of mibefradil, NNC 55-0396 or nickel induced a concentration-dependent inhibition of the amplitude and frequency of the spontaneous Ca(2+) transients and contractions. Mibefradil, NNC 55-0396 or nickel also attenuated the slope of rising phase of spontaneous Ca(2+) transients consistent with the reduction of the frequency. It is concluded that T-type Ca(2+) channels are expressed in the pregnant rat myometrium and may play a key role for the regulation of the frequency of spontaneous phasic contractions.
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Affiliation(s)
- Si-Eun Lee
- Department of Physiology, BK 21 Project for Medical Sciences, College of Medicine, Yonsei University, Seoul 120-752, Korea
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21
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Terry KK, Lebel WS, Riccardi KA, Grasser WA, Thompson DD, Paralkar VM. Effects of gestational age on prostaglandin EP receptor expression and functional involvement during in vitro contraction of the guinea pig uterus. Prostaglandins Leukot Essent Fatty Acids 2008; 78:3-10. [PMID: 18036799 DOI: 10.1016/j.plefa.2007.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Accepted: 10/12/2007] [Indexed: 11/27/2022]
Abstract
Prostaglandin E(2) (PGE(2)) exerts diverse biological effects through four G-protein-coupled cell surface receptor subtypes, EP1-4. This study's objective was to characterize EP1-4 receptor mRNA expression within pregnant guinea pig myometrium during early implantation stage (gestation day [GD] 6) and late stage gestation (GD 50) and evaluate in vitro contractile activity of receptor subtype selective agonists. Using RT-PCR, qualitative gene expression patterns of EP2, EP3, and EP4 mRNA were detected in the myometrium and remained unchanged between the gestational ages. EP1 mRNA remained undetected in pregnant tissue. In vitro contractile activity was evaluated in GD 6 and GD 50 myometrium using vehicle and EP agonists PGE(2), 17-phenyl trinor PGE(2), sulprostone, misoprostol, and CP-533,536. All spasmogens in pregnant myometrium were EP1/EP3 selective agonists, though likely acting via EP3 receptors in this test model. CP-533,536--a highly selective EP2 receptor agonist--and the vehicle failed to induce myometrial contraction at both gestational ages.
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Affiliation(s)
- K K Terry
- Pfizer Global Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT 06340, USA.
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22
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Taggart MJ, Morgan KG. Regulation of the uterine contractile apparatus and cytoskeleton. Semin Cell Dev Biol 2007; 18:296-304. [PMID: 17582796 PMCID: PMC2001260 DOI: 10.1016/j.semcdb.2007.05.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Accepted: 05/03/2007] [Indexed: 01/16/2023]
Abstract
Parturition at term, the end stage of a successful pregnancy, occurs as a result of powerful, co-ordinated and periodic contractions of uterine smooth muscle (myometrium). To occur in a propitious manner, a high degree of control over the activation of a myometrial cell is required. We review the molecular mechanisms and structural composition of myometrial cells that may contribute to their increased contractile capacity at term. We focus attention on pathways that lead to the activation of filamentous networks traditionally labeled 'contractile' or 'cytoskeletal' yet draw attention to the fact that functional discrimination between these systems is not absolute.
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Affiliation(s)
- Michael J Taggart
- Maternal & Fetal Health Research Centre & Cardiovascular Research Group, University of Manchester, St Mary’s Hospital, Hathersage Road, Manchester, M130JH, UK, Tel: +44 161 276 5469, Fax: +44 161 276 6134, E mail:
| | - Kathleen G Morgan
- Health Sciences Department, Sargent College, Boston University, 635 Commonwealth Avenue, Boston MA 02215, USA, Tel: 617-353-7464, Fax: 617-353-7567, E-mail:
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23
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Sanborn BM. Hormonal signaling and signal pathway crosstalk in the control of myometrial calcium dynamics. Semin Cell Dev Biol 2007; 18:305-14. [PMID: 17627855 PMCID: PMC2000447 DOI: 10.1016/j.semcdb.2007.05.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Accepted: 05/03/2007] [Indexed: 10/23/2022]
Abstract
Understanding the basis for the control of myometrial contractant and relaxant signaling pathways is important to understanding how to manage myometrial contractions. Signaling pathways are influenced by the level of expression of the signals and signal pathway components, the location of these components in the appropriate subcellular environment, and covalent modification. Crosstalk between these pathways regulates the effectiveness of signal transduction and represents an important way by which hormones can regulate phenotype. This review deals primarily with signaling pathways that control Ca2+ entry and intracellular release, as well as the interplay between these pathways.
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Affiliation(s)
- Barbara M Sanborn
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1680, USA.
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24
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Blanks AM, Shmygol A, Thornton S. Preterm labour. Myometrial function in prematurity. Best Pract Res Clin Obstet Gynaecol 2007; 21:807-19. [PMID: 17446138 DOI: 10.1016/j.bpobgyn.2007.03.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The primary function of the uterus during gestation is to harbour the growing conceptus in a largely quiescent environment. Upon maturation of the fetus to a point sufficient for extrauterine survival, the uterus must remodel itself sufficiently to generate forceful contractions during labour. During preterm delivery, the process of remodelling of the myometrium occurs early due to a number of different causes, although the underlying basis for myometrial contraction remains the same. This review summarises the anatomical, physiological and molecular basis for contraction. We describe the fibre structure of the human uterus and how this relates to the spread of electrical excitation during a contraction. The process of excitation within a single myometrial cell is described, as well as how this relates to contraction. We then focus on how excitation-contraction coupling is modulated by intercellular communication, pharmacomechanical-coupling and hormonal milieu. Lastly, we consider the actions of the commonly accepted uterine agonists oxytocin, prostaglandin F(2alpha), and prostaglandin E(2), and the tocolytic ritodrine.
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Affiliation(s)
- Andrew M Blanks
- Clinical Sciences Research Institute, University of Warwick, University Hospitals of Coventry and Warwickshire, Clifford Bridge Road, Coventry CV2 2DX, UK.
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25
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Brown A, Cornwell T, Korniyenko I, Solodushko V, Bond CT, Adelman JP, Taylor MS. Myometrial expression of small conductance Ca2+-activated K+ channels depresses phasic uterine contraction. Am J Physiol Cell Physiol 2007; 292:C832-40. [PMID: 17296820 DOI: 10.1152/ajpcell.00268.2006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mechanisms regulating uterine contractility are poorly understood. We hypothesized that a specific isoform of small conductance Ca2+-activated K+ (SK) channel, SK3, promotes feedback regulation of myometrial Ca2+ and hence relaxation of the uterus. To determine the specific functional impact of SK3 channels, we assessed isometric contractions of uterine strips from genetically altered mice (SK3T/T), in which SK3 is overexpressed and can be suppressed by oral administration of doxycycline (SK3T/T+Dox). We found SK3 protein in mouse myometrium, and this expression was substantially higher in SK3T/T mice and lower in SK3T/T+Dox mice compared with wild-type (WT) controls. Sustained contractions elicited by 60 mM KCl were not different among SK3T/T, SK3T/T+Dox, and WT mice. However, the rate of onset and magnitude of spontaneously occurring phasic contractions was muted significantly in isolated uterine strips from SK3T/T mice compared with those from WT mice. These spontaneous contractions were augmented greatly by blockade of SK channels with apamin or by suppression of SK3 expression. Phasic but not tonic contraction in response to oxytocin was depressed in uterine strips from SK3T/T mice, whereas suppression of SK3 channel expression or treatment with apamin promoted the predominance of large coordinated phasic events over tone. Spontaneous contractions and the phasic component of oxytocin contractions were blocked by nifedipine but not by cyclopiazonic acid. Our findings suggest that SK3 channels play an important role in regulating uterine function by limiting influx through L-type Ca2+ channels and disrupting the development of concerted phasic contractile events.
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Affiliation(s)
- Amber Brown
- Dept. of Physiology, College of Medicine, Univ. of South Alabama, 307 University Blvd., MSB 3074, Mobile, AL 36688, USA
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26
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Colpaert EE, Levent A, Lefebvre RA. Nitric oxide relaxes circular smooth muscle of rat distal colon through RhoA/Rho-kinase independent Ca2+ desensitisation. Br J Pharmacol 2005; 144:588-94. [PMID: 15655498 PMCID: PMC1576038 DOI: 10.1038/sj.bjp.0706111] [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: 11/09/2022] Open
Abstract
1. The aim of this study in circular smooth muscle of rat distal colon was to determine whether Ca(2+) desensitisation, in addition to mechanisms lowering cytosolic free Ca(2+) concentration ([Ca(2+)](cyt)), was involved in the relaxation elicited by nitric oxide (NO). Changes in isometric tension and [Ca(2+)](cyt) were recorded simultaneously in fura-2-loaded strips. 2. In methacholine (10(-5) M)-precontracted preparations, exogenous NO (10(-4) M), adenosine 5'-triphosphate (ATP; 10(-3) M) and electrical field stimulation (EFS; 1 ms, 40 V, 4 Hz, 1 min) induced a decrease in smooth muscle tension, which was accompanied by a fall in [Ca(2+)](cyt). 3. The sarcoplasmic/endoplasmic reticulum Ca(2+) ATP-ase (SERCA) inhibitor thapsigargin (10(-6) M) did not exert an influence on the decrease in tension produced by exogenous NO, but significantly attenuated the fall in [Ca(2+)](cyt). Both the relaxation and the fall in [Ca(2+)](cyt) to ATP and EFS were unaffected by thapsigargin. 4. Calyculin-A (10(-6) M), a myosin light chain phosphatase (MLCP) inhibitor, significantly reduced the decrease in tension elicited by exogenous NO, but did not alter the fall in [Ca(2+)](cyt) to exogenous NO. Inactivating RhoA by exoenzyme C3 (2 mug ml(-1)) or inhibiting Rho-kinase with (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide dihydrochloride monohydrate (Y-27632; 10(-5) M) had no effect on the decrease of both tension and [Ca(2+)](cyt) generated by exogenous NO. 5. This paper demonstrates that a RhoA/Rho-kinase independent Ca(2+) desensitisation pathway contributes to the relaxation by NO in circular smooth muscle strips of rat distal colon.
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Affiliation(s)
- Erwin E Colpaert
- Heymans Institute of Pharmacology, Ghent University, De Pintelaan 185, B-9000, Ghent, Belgium
| | - Adnan Levent
- Heymans Institute of Pharmacology, Ghent University, De Pintelaan 185, B-9000, Ghent, Belgium
- Department of Pharmacology, Medical Faculty, Mersin University Campus, Yenişehir, 33169 Mersin, Turkey
| | - Romain A Lefebvre
- Heymans Institute of Pharmacology, Ghent University, De Pintelaan 185, B-9000, Ghent, Belgium
- Author for correspondence:
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Cario-Toumaniantz C, Reillaudoux G, Sauzeau V, Heutte F, Vaillant N, Finet M, Chardin P, Loirand G, Pacaud P. Modulation of RhoA-Rho kinase-mediated Ca2+ sensitization of rabbit myometrium during pregnancy - role of Rnd3. J Physiol 2004; 552:403-13. [PMID: 14561824 PMCID: PMC2343375 DOI: 10.1113/jphysiol.2003.047738] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
During pregnancy, the uterus undergoes major functional and structural remodelling. It is well known that during the major part of pregnancy, the myometrium normally remains relatively quiescent but is able to generate powerful contractions at the time of parturition. However, the intracellular molecular events regulating myometrial contractility during pregnancy still remain poorly understood. We applied differential gene expression screening using cDNA array technology to probe myometrium samples from non-pregnant and mid-pregnant (15 days) rabbits. Among the differentially expressed genes, the farnesylated small G-protein of the Rho family, Rnd3, was found to be upregulated (3.6-fold) at mid-pregnancy. Upregulation of Rnd3 was confirmed at the protein level by a 3.4-fold increase in Rnd3 expression in mid-pregnant myometrium. Measurements of contractile properties of beta-escin permeabilized smooth muscle strips revealed that the upregulation of Rnd3 correlated with an inhibition of RhoA-Rho kinase-mediated Ca2+ sensitization at mid-pregnancy. Treatment of muscle strips from mid-pregnant myometrium with the farnesyl-transferase inhibitor manumycin A (10 muM) led to the recovery of RhoA-Rho kinase-dependent Ca2+ sensitization. At late pregnancy (31 days), upregulation of RhoA and Rho kinase expression was associated with an increase in Ca2+ sensitivity of contractile proteins that was inhibited by the Rho kinase inhibitor Y-27632 (10 muM). These data thus demonstrate the time-dependent regulation of the RhoA-Rho kinase-mediated Ca2+ sensitization during the course of pregnancy. The depression of this mechanism at mid-pregnancy followed by its constitutive activation near term is associated with a co-ordinated modulation of Rnd3, RhoA and Rho kinase expression. The RhoA-Rho kinase signalling pathway and its regulators might thus represent potential targets for the development of new treatments for pre-term labour.
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28
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Cheng H, Althouse GC, Hsu WH. Concentrations of endogenous prostaglandin F2alpha in boar semen and effect of a 72-h incubation period on exogenous prostaglandin F2alpha concentration in extended boar semen. Prostaglandins Other Lipid Mediat 2003; 70:285-90. [PMID: 12611493 DOI: 10.1016/s0090-6980(02)00140-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PGF2alpha in semen has been shown to induce uterine contractions, thereby, facilitating sperm transport during fertilization. Previously, we demonstrated that extended boar semen used in artificial insemination does not increase myometrial contractility, but PGF2alpha supplementation did. In this study, we determined the concentrations of endogenous PGF2alpha in pre-sperm and sperm-rich fractions of the boar ejaculate and examined whether changes in the concentration of exogenous PGF2alpha occurred when added to extended boar semen after 72-h incubation at a 17 degrees C storage temperature. Concentrations of endogenous PGF2alpha (n = 10 boars) in pre-sperm and sperm-rich fractions were 69.6 +/- 7.6 and 58.9 +/- 4.4 pg/ml, respectively. No differences were observed in the concentrations of exogenous PGF2alpha in the extended boar semen at 0 h (59.3 +/- 3.3 microg/ml) and after a 72-h incubation period (52.0 +/- 2.1 microg/ml). These results suggest that the concentration of endogenous PGF2alpha in boar semen used for artificial insemination is < 100 pg/ml. The concentration of exogenous PGF2alpha in the extended boar semen did not differ after 72 h, which indicates that it is not metabolized during this period of time.
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Affiliation(s)
- Henrique Cheng
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA.
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