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Muir R, Khan R, Shmygol A, Quenby S, Elmes M. The impact of maternal obesity on in vivo uterine contractile activity during parturition in the rat. Physiol Rep 2023; 11:e15610. [PMID: 36863718 PMCID: PMC9981334 DOI: 10.14814/phy2.15610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/21/2023] [Accepted: 01/21/2023] [Indexed: 03/04/2023] Open
Abstract
Maternal obesity is associated with increased risk of prolonged and dysfunctional labor and emergency caesarean section. To elucidate the mechanisms behind the associated uterine dystocia, a translational animal model is required. Our previous work identified that exposure to a high-fat, high-cholesterol (HFHC) diet to induce obesity down-regulates uterine contractile associated protein expression and causes asynchronous contractions ex vivo. This study aims to investigate the impact of maternal obesity on uterine contractile function in vivo using intrauterine telemetry surgery. Virgin female Wistar rats were fed either a control (CON, n = 6) or HFHC (n = 6) diet for 6 weeks prior to conception, and throughout pregnancy. On Day 9 of gestation, a pressure-sensitive catheter was surgically implanted aseptically within the gravid uterus. Following 5 days recovery, intrauterine pressure (IUP) was recorded continuously until delivery of the 5th pup (Day 22). HFHC induced obesity led to a significant 1.5-fold increase in IUP (p = 0.026) and fivefold increase in frequency of contractions (p = 0.013) relative to CON. Determination of the time of labor onset identified that HFHC rats IUP (p = 0.046) increased significantly 8 h prior to 5th pup delivery, which contrasts to CON with no significant increase. Myometrial contractile frequency in HFHC rats significantly increased 12 h prior to delivery of the 5th pup (p = 0.023) compared to only 3 h in CON, providing evidence that labor in HFHC rats was prolonged by 9 h. In conclusion, we have established a translational rat model that will allow us to unravel the mechanism behind uterine dystocia associated with maternal obesity.
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Affiliation(s)
- Ronan Muir
- Division of Food Nutrition and Dietetics, School of BioscienceUniversity of Nottingham, Sutton Bonington CampusLoughboroughEnglandUK
| | - Raheela Khan
- Graduate School of MedicineUniversity of Nottingham, Royal Derby HospitalDerbyEnglandUK
| | - Anatoly Shmygol
- Department of Physiology, College of Medicine and Health SciencesUnited Arab Emirates UniversityAl AinUAE
| | - Siobhan Quenby
- Biomedical Research Unit in Reproductive HealthUniversity Hospital Coventry and WarwickshireCoventryUK
| | - Matthew Elmes
- Division of Food Nutrition and Dietetics, School of BioscienceUniversity of Nottingham, Sutton Bonington CampusLoughboroughEnglandUK
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2
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Shmygol A. Beyond Nernst: the effects of extracellular potassium on post-tetanic twitch potentiation in skeletal muscle. Pflugers Arch 2022; 474:573-574. [DOI: 10.1007/s00424-022-02704-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 05/04/2022] [Indexed: 11/28/2022]
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Al Kury LT, Sydorenko V, Smail MMA, Qureshi MA, Shmygol A, Papandreou D, Singh J, Howarth FC. Calcium signaling in endocardial and epicardial ventricular myocytes from streptozotocin-induced diabetic rats. J Diabetes Investig 2021; 12:493-500. [PMID: 33112506 PMCID: PMC8015823 DOI: 10.1111/jdi.13451] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/08/2020] [Accepted: 10/22/2020] [Indexed: 12/16/2022] Open
Abstract
AIMS/INTRODUCTION Abnormalities in Ca2+ signaling have a key role in hemodynamic dysfunction in diabetic heart. The purpose of this study was to explore the effects of streptozotocin (STZ)-induced diabetes on Ca2+ signaling in epicardial (EPI) and endocardial (ENDO) cells of the left ventricle after 5-6 months of STZ injection. MATERIALS AND METHODS Whole-cell patch clamp was used to measure the L-type Ca2+ channel (LTCC) and Na+ /Ca2+ exchanger currents. Fluorescence photometry techniques were used to measure intracellular free Ca2+ concentration. RESULTS Although the LTCC current was not significantly altered, the amplitude of Ca2+ transients increased significantly in EPI-STZ and ENDO-STZ compared with controls. Time to peak LTCC current, time to peak Ca2+ transient, time to half decay of LTCC current and time to half decay of Ca2+ transients were not significantly changed in EPI-STZ and ENDO-STZ myocytes compared with controls. The Na+ /Ca2+ exchanger current was significantly smaller in EPI-STZ and in ENDO-STZ compared with controls. CONCLUSIONS STZ-induced diabetes resulted in an increase in amplitude of Ca2+ transients in EPI and ENDO myocytes that was independent of the LTCC current. Such an effect can be attributed, at least in part, to the dysfunction of the Na+ /Ca2+ exchanger. Additional studies are warranted to improve our understanding of the regional impact of diabetes on Ca2+ signaling, which will facilitate the discovery of new targeted treatments for diabetic cardiomyopathy.
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Affiliation(s)
- Lina T Al Kury
- Department of Health SciencesCollege of Natural and Health SciencesZayed UniversityAbu DhabiUnited Arab Emirates
| | - Vadym Sydorenko
- Department of Cellular MembranologyBogomoletz Institute of PhysiologyKievUkraine
| | - Manal MA Smail
- Department of PhysiologyCollege of Medicine and Health SciencesUAE UniversityAl AinUnited Arab Emirates
| | - Muhammad A Qureshi
- Department of PhysiologyCollege of Medicine and Health SciencesUAE UniversityAl AinUnited Arab Emirates
| | - Anatoly Shmygol
- Department of PhysiologyCollege of Medicine and Health SciencesUAE UniversityAl AinUnited Arab Emirates
| | - Dimitrios Papandreou
- Department of Health SciencesCollege of Natural and Health SciencesZayed UniversityAbu DhabiUnited Arab Emirates
| | - Jaipaul Singh
- School of Forensic and Applied SciencesUniversity of Central LancashirePrestonUK
| | - Frank Christopher Howarth
- Department of PhysiologyCollege of Medicine and Health SciencesUAE UniversityAl AinUnited Arab Emirates
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Shmygol A. Pacing made easy: dynamic clamp promotes quantitative understanding of cardiac autorhythmicity and boosts the development of new pacemakers. Pflugers Arch 2020; 472:549-550. [PMID: 32415462 DOI: 10.1007/s00424-020-02392-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 04/29/2020] [Accepted: 05/04/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Anatoly Shmygol
- Department of Physiology, College of Medicine and Health Sciences, United Arab University, Al Ain, UAE.
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Shmygol A. Calcium-induced calcium release in astroglia-a view "from the inside". Pflugers Arch 2020; 472:435-436. [PMID: 32219530 DOI: 10.1007/s00424-020-02366-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 03/09/2020] [Accepted: 03/12/2020] [Indexed: 02/08/2023]
Affiliation(s)
- Anatoly Shmygol
- Department of Physiology, College of Medicine and Health Sciences, United Arab University, Al Ain, UAE.
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Muir R, Liu G, Khan R, Shmygol A, Quenby S, Gibson RA, Muhlhausler B, Elmes M. Author Correction: Maternal obesity-induced decreases in plasma, hepatic and uterine polyunsaturated fatty acids during labour is reversed through improved nutrition at conception. Sci Rep 2018; 8:14716. [PMID: 30258197 PMCID: PMC6158297 DOI: 10.1038/s41598-018-33001-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Ronan Muir
- Division of Nutritional Science, School of Bioscience, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, England, United Kingdom
| | - Ge Liu
- Healthy Mothers, Babies and Children's Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, Australia
| | - Raheela Khan
- Graduate School of Medicine, University of Nottingham, Royal Derby Hospital, Uttoxeter Road, Derby, DE22 3DT, England, United Kingdom
| | - Anatoly Shmygol
- Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, P. O. Box 17666, UAE
| | - Siobhan Quenby
- Biomedical Research Unit in Reproductive Health, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, CV2 2DX, Warwickshire, United Kingdom
| | - Robert Alan Gibson
- Healthy Mothers, Babies and Children's Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, Australia.,Department of Wine and Food Science, FOODplus Research Centre, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, Australia
| | - Beverly Muhlhausler
- Healthy Mothers, Babies and Children's Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, Australia.,Department of Wine and Food Science, FOODplus Research Centre, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, Australia
| | - Matthew Elmes
- Division of Nutritional Science, School of Bioscience, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, England, United Kingdom.
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Testrow CP, Holden AV, Shmygol A, Zhang H. A computational model of excitation and contraction in uterine myocytes from the pregnant rat. Sci Rep 2018; 8:9159. [PMID: 29904075 PMCID: PMC6002389 DOI: 10.1038/s41598-018-27069-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 05/24/2018] [Indexed: 12/17/2022] Open
Abstract
Aberrant uterine myometrial activities in humans are major health issues. However, the cellular and tissue mechanism(s) that maintain the uterine myometrium at rest during gestation, and that initiate and maintain long-lasting uterine contractions during delivery are incompletely understood. In this study we construct a computational model for describing the electrical activity (simple and complex action potentials), intracellular calcium dynamics and mechanical contractions of isolated uterine myocytes from the pregnant rat. The model reproduces variant types of action potentials - from spikes with a smooth plateau, to spikes with an oscillatory plateau, to bursts of spikes - that are seen during late gestation under different physiological conditions. The effects of the hormones oestradiol (via reductions in calcium and potassium selective channel conductance), oxytocin (via an increase in intracellular calcium release) and the tocolytic nifedipine (via a block of L-type calcium channels currents) on action potentials and contractions are also reproduced, which quantitatively match to experimental data. All of these results validated the cell model development. In conclusion, the developed model provides a computational platform for further investigations of the ionic mechanism underlying the genesis and control of electrical and mechanical activities in the rat uterine myocytes.
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Affiliation(s)
- Craig P Testrow
- The University of Manchester, School of Physics and Astronomy, Manchester, M13 9PL, UK
| | - Arun V Holden
- The University of Leeds, School of Biomedical Sciences, Leeds, LS2 9JT, UK
| | - Anatoly Shmygol
- United Arab Emirates University, College of Medicine and Health Sciences, Department of Physiology, Al-Ain, P.O. Box 17666, Emirates, UAE
| | - Henggui Zhang
- The University of Manchester, School of Physics and Astronomy, Manchester, M13 9PL, UK.
- School of Computer Science and Technology, Harbin Institute of Technology (HIT), Harbin, 150001, China.
- Space Institute of Southern China, Shenzhen, 518117, China.
- Key laboratory of Medical Electrophysiology, Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease/Institute of Cardiovascular Research, Southwest Medical University, Luzhou, 646000, China.
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Howarth FC, Al Kury L, Sydorenko V, Smail MMA, Qureshi MA, Shmygol A, Oz M, Singh J. P75Shortening and calcium transport in epicardial and endocardial ventricular myocytes from the streptozotocin-induced diabetic rat. Cardiovasc Res 2018. [DOI: 10.1093/cvr/cvy060.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- F C Howarth
- United Arab Emirates University, Physiology, Al Ain, United Arab Emirates
| | - L Al Kury
- Zayed University, Abu Dhabi, United Arab Emirates
| | - V Sydorenko
- Bogomoletz Institute of Physiology, Kiev, Ukraine
| | - MMA Smail
- United Arab Emirates University, Physiology, Al Ain, United Arab Emirates
| | - M A Qureshi
- United Arab Emirates University, Physiology, Al Ain, United Arab Emirates
| | - A Shmygol
- United Arab Emirates University, Physiology, Al Ain, United Arab Emirates
| | - M Oz
- Qatar University, Doha, Qatar
| | - J Singh
- University of Central Lancashire, Preston, United Kingdom
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Muir R, Liu G, Khan R, Shmygol A, Quenby S, Gibson RA, Muhlhausler B, Elmes M. Maternal obesity-induced decreases in plasma, hepatic and uterine polyunsaturated fatty acids during labour is reversed through improved nutrition at conception. Sci Rep 2018; 8:3389. [PMID: 29467407 PMCID: PMC5821893 DOI: 10.1038/s41598-018-21809-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 02/12/2018] [Indexed: 11/09/2022] Open
Abstract
Maternal obesity is associated with prolonged and dysfunctional labour, potentially through decreased synthesis of prostaglandins that stimulate myometrial contractions. We assessed the impact of maternal obesity on concentrations of precursor fatty acids (FA) for prostaglandin synthesis and whether any changes could be reversed by improved nutrition post-conception. Wistar rats were fed control (CON) or High-Fat, High-cholesterol (HFHC) diets 6 weeks before mating. At conception half the dams switched diets providing 4 dietary groups: (1) CON, (2) HFHC, (3) CON-HFHC or (4) HFHC-CON. During parturition rats were euthanized and FA composition of plasma, liver and uterus determined. Visceral fat was doubled in rats exposed to the HFHC diet prior to and/or during pregnancy compared to CON. HFHC diet increased MUFAs but decreased omega-3 and omega-6 PUFAs in plasma and liver. Uterine omega-3 FA concentrations were halved in HFHC versus CON rats, but all other FAs were similar. Switching from HFHC to CON diet at conception restored all FA profiles to those seen in CON rats. The increased MUFA and decreased PUFA concentrations in obese HFHC dams may contribute to aberrant prostaglandin synthesis and dysfunctional myometrial activity and it may be possible to reverse these changes, and potentially improve labour outcomes, by improving nutrition at conception.
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Affiliation(s)
- Ronan Muir
- Division of Nutritional Science, School of Bioscience, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, England, United Kingdom
| | - Ge Liu
- Healthy Mothers, Babies and Children's Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, Australia
| | - Raheela Khan
- Graduate School of Medicine, University of Nottingham, Royal Derby Hospital, Uttoxeter Road, Derby, DE22 3DT, England, United Kingdom
| | - Anatoly Shmygol
- Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, P. O. Box 17666, UAE
| | - Siobhan Quenby
- Biomedical Research Unit in Reproductive Health, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, CV2 2DX, Warwickshire, United Kingdom
| | - Robert Alan Gibson
- Healthy Mothers, Babies and Children's Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, Australia.,Department of Wine and Food Science, FOODplus Research Centre, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, Australia
| | - Beverly Muhlhausler
- Healthy Mothers, Babies and Children's Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, Australia.,Department of Wine and Food Science, FOODplus Research Centre, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, Australia
| | - Matthew Elmes
- Division of Nutritional Science, School of Bioscience, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, England, United Kingdom.
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Al Kury L, Smail M, Qureshi MA, Sydorenko V, Shmygol A, Oz M, Singh J, Howarth FC. Calcium Signaling in the Ventricular Myocardium of the Goto-Kakizaki Type 2 Diabetic Rat. J Diabetes Res 2018; 2018:2974304. [PMID: 29850600 PMCID: PMC5914098 DOI: 10.1155/2018/2974304] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 01/16/2018] [Accepted: 03/08/2018] [Indexed: 12/18/2022] Open
Abstract
The association between diabetes mellitus (DM) and high mortality linked to cardiovascular disease (CVD) is a major concern worldwide. Clinical and preclinical studies have demonstrated a variety of diastolic and systolic dysfunctions in patients with type 2 diabetes mellitus (T2DM) with the severity of abnormalities depending on the patients' age and duration of diabetes. The cellular basis of hemodynamic dysfunction in a type 2 diabetic heart is still not well understood. The aim of this review is to evaluate our current understanding of contractile dysfunction and disturbances of Ca2+ transport in the Goto-Kakizaki (GK) diabetic rat heart. The GK rat is a widely used nonobese, nonhypertensive genetic model of T2DM which is characterized by insulin resistance, elevated blood glucose, alterations in blood lipid profile, and cardiac dysfunction.
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Affiliation(s)
- L. Al Kury
- College of Natural and Health Sciences, Zayed University, Abu Dhabi, UAE
| | - M. Smail
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - M. A. Qureshi
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - V. Sydorenko
- Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kiev, Ukraine
| | - A. Shmygol
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - M. Oz
- Department of Basic Medical Sciences, College of Medicine, Qatar University, Doha, Qatar
| | - J. Singh
- School of Forensic & Applied Sciences, University of Central Lancashire, Preston, UK
| | - F. C. Howarth
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
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Muter J, Brighton PJ, Lucas ES, Lacey L, Shmygol A, Quenby S, Blanks AM, Brosens JJ. Progesterone-Dependent Induction of Phospholipase C-Related Catalytically Inactive Protein 1 (PRIP-1) in Decidualizing Human Endometrial Stromal Cells. Endocrinology 2016; 157:2883-93. [PMID: 27167772 PMCID: PMC4972893 DOI: 10.1210/en.2015-1914] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Decidualization denotes the transformation of endometrial stromal cells into specialized decidual cells. In pregnancy, decidual cells form a protective matrix around the implanting embryo, enabling coordinated trophoblast invasion and formation of a functional placenta. Continuous progesterone (P4) signaling renders decidual cells resistant to various environmental stressors, whereas withdrawal inevitably triggers tissue breakdown and menstruation or miscarriage. Here, we show that PLCL1, coding phospholipase C (PLC)-related catalytically inactive protein 1 (PRIP-1), is highly induced in response to P4 signaling in decidualizing human endometrial stromal cells (HESCs). Knockdown experiments in undifferentiated HESCs revealed that PRIP-1 maintains basal phosphoinositide 3-kinase/Protein kinase B activity, which in turn prevents illicit nuclear translocation of the transcription factor forkhead box protein O1 and induction of the apoptotic activator BIM. By contrast, loss of this scaffold protein did not compromise survival of decidual cells. PRIP-1 knockdown did also not interfere with the responsiveness of HESCs to deciduogenic cues, although the overall expression of differentiation markers, such as PRL, IGFBP1, and WNT4, was blunted. Finally, we show that PRIP-1 in decidual cells uncouples PLC activation from intracellular Ca(2+) release by attenuating inositol 1,4,5-trisphosphate signaling. In summary, PRIP-1 is a multifaceted P4-inducible scaffold protein that gates the activity of major signal transduction pathways in the endometrium. It prevents apoptosis of proliferating stromal cells and contributes to the relative autonomy of decidual cells by silencing PLC signaling downstream of Gq protein-coupled receptors.
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Affiliation(s)
- Joanne Muter
- Division of Biomedical Sciences (J.M., P.J.B., E.S.L., L.L., A.S., S.Q., A.M.B., J.J.B.), Warwick Medical School, University of Warwick, Coventry CV4 7AL, United Kingdom; and University Hospitals Coventry and Warwickshire National Health Service Trust (S.Q., J.J.B.), Coventry, CV2 2DX United Kingdom; and Tommy's National Miscarriage Research Centre (E.S.L., S.Q., J.J.B.), University Hospital Coventry and Warwickshire, Coventry, CV2 2DX United Kingdom
| | - Paul J Brighton
- Division of Biomedical Sciences (J.M., P.J.B., E.S.L., L.L., A.S., S.Q., A.M.B., J.J.B.), Warwick Medical School, University of Warwick, Coventry CV4 7AL, United Kingdom; and University Hospitals Coventry and Warwickshire National Health Service Trust (S.Q., J.J.B.), Coventry, CV2 2DX United Kingdom; and Tommy's National Miscarriage Research Centre (E.S.L., S.Q., J.J.B.), University Hospital Coventry and Warwickshire, Coventry, CV2 2DX United Kingdom
| | - Emma S Lucas
- Division of Biomedical Sciences (J.M., P.J.B., E.S.L., L.L., A.S., S.Q., A.M.B., J.J.B.), Warwick Medical School, University of Warwick, Coventry CV4 7AL, United Kingdom; and University Hospitals Coventry and Warwickshire National Health Service Trust (S.Q., J.J.B.), Coventry, CV2 2DX United Kingdom; and Tommy's National Miscarriage Research Centre (E.S.L., S.Q., J.J.B.), University Hospital Coventry and Warwickshire, Coventry, CV2 2DX United Kingdom
| | - Lauren Lacey
- Division of Biomedical Sciences (J.M., P.J.B., E.S.L., L.L., A.S., S.Q., A.M.B., J.J.B.), Warwick Medical School, University of Warwick, Coventry CV4 7AL, United Kingdom; and University Hospitals Coventry and Warwickshire National Health Service Trust (S.Q., J.J.B.), Coventry, CV2 2DX United Kingdom; and Tommy's National Miscarriage Research Centre (E.S.L., S.Q., J.J.B.), University Hospital Coventry and Warwickshire, Coventry, CV2 2DX United Kingdom
| | - Anatoly Shmygol
- Division of Biomedical Sciences (J.M., P.J.B., E.S.L., L.L., A.S., S.Q., A.M.B., J.J.B.), Warwick Medical School, University of Warwick, Coventry CV4 7AL, United Kingdom; and University Hospitals Coventry and Warwickshire National Health Service Trust (S.Q., J.J.B.), Coventry, CV2 2DX United Kingdom; and Tommy's National Miscarriage Research Centre (E.S.L., S.Q., J.J.B.), University Hospital Coventry and Warwickshire, Coventry, CV2 2DX United Kingdom
| | - Siobhan Quenby
- Division of Biomedical Sciences (J.M., P.J.B., E.S.L., L.L., A.S., S.Q., A.M.B., J.J.B.), Warwick Medical School, University of Warwick, Coventry CV4 7AL, United Kingdom; and University Hospitals Coventry and Warwickshire National Health Service Trust (S.Q., J.J.B.), Coventry, CV2 2DX United Kingdom; and Tommy's National Miscarriage Research Centre (E.S.L., S.Q., J.J.B.), University Hospital Coventry and Warwickshire, Coventry, CV2 2DX United Kingdom
| | - Andrew M Blanks
- Division of Biomedical Sciences (J.M., P.J.B., E.S.L., L.L., A.S., S.Q., A.M.B., J.J.B.), Warwick Medical School, University of Warwick, Coventry CV4 7AL, United Kingdom; and University Hospitals Coventry and Warwickshire National Health Service Trust (S.Q., J.J.B.), Coventry, CV2 2DX United Kingdom; and Tommy's National Miscarriage Research Centre (E.S.L., S.Q., J.J.B.), University Hospital Coventry and Warwickshire, Coventry, CV2 2DX United Kingdom
| | - Jan J Brosens
- Division of Biomedical Sciences (J.M., P.J.B., E.S.L., L.L., A.S., S.Q., A.M.B., J.J.B.), Warwick Medical School, University of Warwick, Coventry CV4 7AL, United Kingdom; and University Hospitals Coventry and Warwickshire National Health Service Trust (S.Q., J.J.B.), Coventry, CV2 2DX United Kingdom; and Tommy's National Miscarriage Research Centre (E.S.L., S.Q., J.J.B.), University Hospital Coventry and Warwickshire, Coventry, CV2 2DX United Kingdom
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12
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Muir R, Ballan J, Clifford B, McMullen S, Khan R, Shmygol A, Quenby S, Elmes M. Modelling maternal obesity: the effects of a chronic high-fat, high-cholesterol diet on uterine expression of contractile-associated proteins and ex vivo contractile activity during labour in the rat. Clin Sci (Lond) 2016; 130:183-92. [PMID: 26543049 PMCID: PMC4682211 DOI: 10.1042/cs20150539] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 10/08/2015] [Accepted: 11/03/2015] [Indexed: 11/17/2022]
Abstract
Maternal obesity is associated with prolonged and dysfunctional labour and emergency caesarean section, but the mechanisms are unknown. The present study investigated the effects of an adiposity-inducing high-fat, high-cholesterol (HFHC) diet on uterine contractile-associated protein (CAP) expression and ex vivo uterine contractility in term non-labouring (TNL) and term labouring (TL) rats. Female rats were fed either control chow (CON n=20) or HFHC (n=20) diet 6 weeks before conception and during pregnancy. On gestational day 21 (TNL) or day 22 (TL) CON and HFHC (n=10) rats were killed to determine plasma cholesterol, triacylglycerol and progesterone concentrations and collection of myometrium for contractility studies and expression of CAPs caveolin-1 (Cav-1), connexin-43 (CX-43) and it's phosphorylated form (pCX-43), oxytocin receptor (OXTR) and cyclooxygenase-2 (COX-2). HFHC feeding increased visceral fat (P≤0.001), plasma cholesterol (P≤0.001) and triacylglycerol (P=0.039) concentrations. Stage of labour effected uterine expression of CAV-1 (P<0.02), pCX43 and COX-2 (both P<0.03). CAV-1 and pCX43 decreased but COX-2 increased with parturition. Significant diet- and labour-stage interactions were evident for CX-43 and pCX43 (P<0.03 and P<0.004 respectively). CX-43 decreased with TL in HFHC animals but was unaltered in CON. pCX-43 fell with labour in CON but remained high in HFHC. OXTR expression was significantly higher in HFHC compared with CON animals (P<0.03). Progesterone was higher in HFHC rats at term (P<0.014) but fell significantly with labour to similar concentrations as CON. Contractility studies identified synchronous contractions of stable amplitude in lean animals, but unstable asynchronous contractions with obesity. Uterine dose response to oxytocin was blunted during labour in HFHC rats with a log EC50 of -8.84 compared with -10.25 M in CON for integral activity (P<0.05). In conclusion, our adiposity model exhibits adverse effects on contractile activity during labour that can be investigated further to unravel the mechanisms causing uterine dystocia in obese women.
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Affiliation(s)
- Ronan Muir
- Division of Nutritional Science, School of Bioscience, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, England, U.K
| | - Jean Ballan
- Division of Nutritional Science, School of Bioscience, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, England, U.K
| | - Bethan Clifford
- Division of Nutritional Science, School of Bioscience, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, England, U.K
| | - Sarah McMullen
- Division of Nutritional Science, School of Bioscience, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, England, U.K
| | - Raheela Khan
- Graduate School of Medicine, University of Nottingham, Royal Derby Hospital, Uttoxeter Road, Derby DE22 3DT, England, U.K
| | - Anatoly Shmygol
- Reproductive Health, University of Warwick, Coventry, Warwickshire CV2 2DX, England, U.K
| | - Siobhan Quenby
- Reproductive Health, University of Warwick, Coventry, Warwickshire CV2 2DX, England, U.K. Biomedical Research Unit in Reproductive Health, University Hospital Coventry and Warwickshire, Coventry, Warwickshire CV2 2DX, U.K
| | - Matthew Elmes
- Division of Nutritional Science, School of Bioscience, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, England, U.K.
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Sheldon RE, Mashayamombe C, Shi SQ, Garfield RE, Shmygol A, Blanks AM, van den Berg HA. Alterations in gap junction connexin43/connexin45 ratio mediate a transition from quiescence to excitation in a mathematical model of the myometrium. J R Soc Interface 2015; 11:20140726. [PMID: 25401181 DOI: 10.1098/rsif.2014.0726] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The smooth muscle cells of the uterus contract in unison during delivery. These cells achieve coordinated activity via electrical connections called gap junctions which consist of aggregated connexin proteins such as connexin43 and connexin45. The density of gap junctions governs the excitability of the myometrium (among other factors). An increase in gap junction density occurs immediately prior to parturition. We extend a mathematical model of the myometrium by incorporating the voltage-dependence of gap junctions that has been demonstrated in the experimental literature. Two functional subtypes exist, corresponding to systems with predominantly connexin43 and predominantly connexin45, respectively. Our simulation results indicate that the gap junction protein connexin45 acts as a negative modulator of uterine excitability, and hence, activity. A network with a higher proportion of connexin45 relative to connexin43 is unable to excite every cell. Connexin45 has much more rapid gating kinetics than connexin43 which we show limits the maximum duration of a local burst of activity. We propose that this effect regulates the degree of synchronous excitation attained during a contraction. Our results support the hypothesis that as labour approaches, connexin45 is downregulated to allow action potentials to spread more readily through the myometrium.
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Xue M, Momiji H, Rabbani N, Barker G, Bretschneider T, Shmygol A, Rand DA, Thornalley PJ. Frequency Modulated Translocational Oscillations of Nrf2 Mediate the Antioxidant Response Element Cytoprotective Transcriptional Response. Antioxid Redox Signal 2015; 23:613-29. [PMID: 25178584 PMCID: PMC4556091 DOI: 10.1089/ars.2014.5962] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Revised: 08/14/2014] [Accepted: 08/31/2014] [Indexed: 12/20/2022]
Abstract
AIMS Stress responsive signaling coordinated by nuclear factor erythroid 2-related factor 2 (Nrf2) provides an adaptive response for protection of cells against toxic insults, oxidative stress and metabolic dysfunction. Nrf2 regulates a battery of protective genes by binding to regulatory antioxidant response elements (AREs). The aim of this study was to examine how Nrf2 signals cell stress status and regulates transcription to maintain homeostasis. RESULTS In live cell microscopy we observed that Nrf2 undergoes autonomous translocational frequency-modulated oscillations between cytoplasm and nucleus. Oscillations occurred in quiescence and when cells were stimulated at physiological levels of activators, they decrease in period and amplitude and then evoke a cytoprotective transcriptional response. We propose a mechanism whereby oscillations are produced by negative feedback involving successive de-phosphorylation and phosphorylation steps. Nrf2 was inactivated in the nucleus and reactivated on return to the cytoplasm. Increased frequency of Nrf2 on return to the cytoplasm with increased reactivation or refresh-rate under stress conditions activated the transcriptional response mediating cytoprotective effects. The serine/threonine-protein phosphatase PGAM5, member of the Nrf2 interactome, was a key regulatory component. INNOVATION We found that Nrf2 is activated in cells without change in total cellular Nrf2 protein concentration. Regulation of ARE-linked protective gene transcription occurs rather through translocational oscillations of Nrf2. We discovered cytoplasmic refresh rate of Nrf2 is important in maintaining and regulating the transcriptional response and links stress challenge to increased cytoplasmic surveillance. We found silencing and inhibition of PGAM5 provides potent activation of Nrf2. CONCLUSION Frequency modulated translocational oscillations of Nrf2 mediate the ARE-linked cytoprotective transcriptional response.
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Affiliation(s)
- Mingzhan Xue
- Clinical Sciences Research Laboratories, Warwick Medical School, University Hospital, University of Warwick, Coventry, United Kingdom
| | - Hiroshi Momiji
- Warwick Systems Biology Centre, University of Warwick, Coventry, United Kingdom
| | - Naila Rabbani
- Clinical Sciences Research Laboratories, Warwick Medical School, University Hospital, University of Warwick, Coventry, United Kingdom
- Warwick Systems Biology Centre, University of Warwick, Coventry, United Kingdom
| | - Guy Barker
- School of Life Sciences, University of Warwick, Wellesbourne, United Kingdom
| | - Till Bretschneider
- Warwick Systems Biology Centre, University of Warwick, Coventry, United Kingdom
| | - Anatoly Shmygol
- Clinical Sciences Research Laboratories, Warwick Medical School, University Hospital, University of Warwick, Coventry, United Kingdom
| | - David A. Rand
- Warwick Systems Biology Centre, University of Warwick, Coventry, United Kingdom
| | - Paul J. Thornalley
- Clinical Sciences Research Laboratories, Warwick Medical School, University Hospital, University of Warwick, Coventry, United Kingdom
- Warwick Systems Biology Centre, University of Warwick, Coventry, United Kingdom
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Xue M, Momiji H, Rabbani N, Barker G, Bretschneider T, Shmygol A, Rand D, Thornalley P. Antioxidant response element cytoprotective response in aortic endothelial cells coordinated by transcription factor Nrf2 is regulated through frequency-modulated translocational oscillations. Atherosclerosis 2015. [DOI: 10.1016/j.atherosclerosis.2015.04.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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McCloskey C, Rada C, Bailey E, McCavera S, van den Berg HA, Atia J, Rand DA, Shmygol A, Chan YW, Quenby S, Brosens JJ, Vatish M, Zhang J, Denton JS, Taggart MJ, Kettleborough C, Tickle D, Jerman J, Wright P, Dale T, Kanumilli S, Trezise DJ, Thornton S, Brown P, Catalano R, Lin N, England SK, Blanks AM. The inwardly rectifying K+ channel KIR7.1 controls uterine excitability throughout pregnancy. EMBO Mol Med 2015; 6:1161-74. [PMID: 25056913 PMCID: PMC4197863 DOI: 10.15252/emmm.201403944] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Abnormal uterine activity in pregnancy causes a range of important clinical disorders, including preterm birth, dysfunctional labour and post-partum haemorrhage. Uterine contractile patterns are controlled by the generation of complex electrical signals at the myometrial smooth muscle plasma membrane. To identify novel targets to treat conditions associated with uterine dysfunction, we undertook a genome-wide screen of potassium channels that are enriched in myometrial smooth muscle. Computational modelling identified Kir7.1 as potentially important in regulating uterine excitability during pregnancy. We demonstrate Kir7.1 current hyper-polarizes uterine myocytes and promotes quiescence during gestation. Labour is associated with a decline, but not loss, of Kir7.1 expression. Knockdown of Kir7.1 by lentiviral expression of miRNA was sufficient to increase uterine contractile force and duration significantly. Conversely, overexpression of Kir7.1 inhibited uterine contractility. Finally, we demonstrate that the Kir7.1 inhibitor VU590 as well as novel derivative compounds induces profound, long-lasting contractions in mouse and human myometrium; the activity of these inhibitors exceeds that of other uterotonic drugs. We conclude Kir7.1 regulates the transition from quiescence to contractions in the pregnant uterus and may be a target for therapies to control uterine contractility.
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Affiliation(s)
- Conor McCloskey
- Division of Reproductive Health, Clinical Sciences Research Laboratories, Warwick Medical School University of Warwick, Coventry, UK
| | - Cara Rada
- Division of Basic Science Research, Department of Obstetrics and Gynecology, School of Medicine Washington University in St. Louis,, St. Louis, MO, USA
| | - Elizabeth Bailey
- Division of Reproductive Health, Clinical Sciences Research Laboratories, Warwick Medical School University of Warwick, Coventry, UK
| | - Samantha McCavera
- Division of Reproductive Health, Clinical Sciences Research Laboratories, Warwick Medical School University of Warwick, Coventry, UK
| | - Hugo A van den Berg
- Warwick Systems Biology & Mathematics Institute University of Warwick, Coventry, UK
| | - Jolene Atia
- Division of Reproductive Health, Clinical Sciences Research Laboratories, Warwick Medical School University of Warwick, Coventry, UK
| | - David A Rand
- Warwick Systems Biology & Mathematics Institute University of Warwick, Coventry, UK
| | - Anatoly Shmygol
- Division of Reproductive Health, Clinical Sciences Research Laboratories, Warwick Medical School University of Warwick, Coventry, UK
| | - Yi-Wah Chan
- Division of Reproductive Health, Clinical Sciences Research Laboratories, Warwick Medical School University of Warwick, Coventry, UK
| | - Siobhan Quenby
- Division of Reproductive Health, Clinical Sciences Research Laboratories, Warwick Medical School University of Warwick, Coventry, UK
| | - Jan J Brosens
- Division of Reproductive Health, Clinical Sciences Research Laboratories, Warwick Medical School University of Warwick, Coventry, UK
| | - Manu Vatish
- Division of Reproductive Health, Clinical Sciences Research Laboratories, Warwick Medical School University of Warwick, Coventry, UK
| | - Jie Zhang
- Division of Reproductive Health, Clinical Sciences Research Laboratories, Warwick Medical School University of Warwick, Coventry, UK
| | - Jerod S Denton
- Vanderbilt Institute of Chemical Biology, Vanderbilt Institute for Global Health Vanderbilt University School of Medicine Medical Center North, Nashville, TN, USA
| | - Michael J Taggart
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK
| | | | - David Tickle
- Centre for Therapeutics and Discovery, Medical Research Council Technologies, London, UK
| | - Jeff Jerman
- Centre for Therapeutics and Discovery, Medical Research Council Technologies, London, UK
| | - Paul Wright
- Centre for Therapeutics and Discovery, Medical Research Council Technologies, London, UK
| | - Timothy Dale
- BioPark, Essen BioScience Ltd, Welwyn Garden City, Hertfordshire, UK
| | | | - Derek J Trezise
- BioPark, Essen BioScience Ltd, Welwyn Garden City, Hertfordshire, UK
| | | | - Pamela Brown
- MRC Centre for Reproductive Health (CRH), Queen's Medical Research Institute University of Edinburgh, Edinburgh, UK
| | - Roberto Catalano
- MRC Centre for Reproductive Health (CRH), Queen's Medical Research Institute University of Edinburgh, Edinburgh, UK
| | - Nan Lin
- Department of Mathematics, Washington University, St. Louis, MO, USA
| | - Sarah K England
- Division of Basic Science Research, Department of Obstetrics and Gynecology, School of Medicine Washington University in St. Louis,, St. Louis, MO, USA
| | - Andrew M Blanks
- Division of Reproductive Health, Clinical Sciences Research Laboratories, Warwick Medical School University of Warwick, Coventry, UK
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Loftus FC, Richardson MJE, Shmygol A. Single-cell mechanics and calcium signalling in organotypic slices of human myometrium. J Biomech 2015; 48:1620-4. [PMID: 25702249 PMCID: PMC4503816 DOI: 10.1016/j.jbiomech.2015.01.046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 01/31/2015] [Indexed: 11/29/2022]
Abstract
Elucidation of cellular mechanisms regulating myometrial contractility is crucial for improvement in management of many obstetric abnormalities, such as premature delivery, uterine dystocia and post-partum haemorrhage. Myometrial contractions are triggered by periodic synchronous rises in intracellular calcium concentration ([Ca(2+)]i) elicited by spontaneously generated action potentials propagating throughout the entire myometrium. During labour, hormones like oxytocin and prostaglandins potentiate uterine contractions by increasing their duration, strength and frequency. The most informative approach to studying the mechanisms underlying hormonal modulation of uterine contractility is to record [Ca(2+)]i responses to hormones in intact myometrial samples that have not been subjected to enzymatic treatment for cell isolation or cell culture conditions. However, the spatio-temporal resolution of such recording is limited due to the motion artifacts occurring in contracting tissue. Here we describe the application of our newly developed motion correction algorithm to investigate the [Ca(2+)]i dynamics in control and oxytocin stimulated slices of human myometrium on a cellular level. We present evidence that oxytocin induces asynchronous [Ca(2+)]i oscillations in individual myocytes within intact myometrium which are similar to those observed in cultured cells. The oscillations occur between synchronous action potential-driven [Ca(2+)]i transients but appear to be unrelated to contractions. Furthermore, the oxytocin-triggered [Ca(2+)]i oscillations wane within 30-50min of hormone application, while the action potential induced [Ca(2+)]i transients remain augmented. We conclude that oxytocin-induced [Ca(2+)]i oscillations are not relevant to the acute regulation of myometrial contractility but may play a role in longer-term regulatory processes, for example, by triggering gene expression.
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Affiliation(s)
- Fiona C Loftus
- Warwick Systems Biology Centre, University of Warwick, Coventry, UK; Division of Translational and Systems Medicine, Warwick Medical School, University of Warwick, Coventry, UK; Warwick Systems Biology Doctoral Training Centre, University of Warwick, Coventry, UK
| | | | - Anatoly Shmygol
- Division of Translational and Systems Medicine, Warwick Medical School, University of Warwick, Coventry, UK.
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Abstract
The uterus undergoes changes throughout a woman's life, beginning with her own embryonic development when she is still in the womb, commencing a monthly cycle at the onset of adulthood, and undergoing dramatic changes during pregnancy and parturition. The impact of preterm labour and other perinatal health problems is significant, both in human and financial terms; therefore the study of the physiological and regulatory changes which the uterus undergoes can be of enormous potential benefit. Here we briefly review the current state of knowledge, with an emphasis on the importance of changes in connectivity in the uterine smooth muscle cell network and on recent mathematical modelling work aimed at elucidating the role of spatial heterogeneity in this connected network.
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Abstract
Successful childbirth depends on the occurrence of precisely coordinated uterine contractions during labour. Calcium indicator fluorescence imaging is one of the main techniques for investigating the mechanisms governing this physiological process and its pathologies. The effective spatiotemporal resolution of calcium signals is, however, limited by the motion of contracting tissue: structures of interest in the order of microns can move over a hundred times their width during a contraction. The simultaneous changes in local intensity and tissue configuration make motion tracking a non-trivial problem in image analysis and confound many of the standard techniques. This paper presents a method that tracks local motion throughout the tissue and allows for the almost complete removal of motion artefacts. This provides a stabilized calcium signal down to a pixel resolution, which, for the data examined, is in the order of a few microns. As a byproduct of image stabilization, a complete kinematic description of the contraction–relaxation cycle is also obtained. This contains novel information about the mechanical response of the tissue, such as the identification of a characteristic length scale, in the order of 40–50 μm, below which tissue motion is homogeneous. Applied to our data, we illustrate that the method allows for analyses of calcium dynamics in contracting myometrium in unprecedented spatiotemporal detail. Additionally, we use the kinematics of tissue motion to compare calcium signals at the subcellular level and local contractile motion. The computer code used is provided in a freely modifiable form and has potential applicability to in vivo calcium imaging of neural tissue, as well as other smooth muscle tissue.
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Affiliation(s)
- Fiona C Loftus
- Warwick Systems Biology Centre, University of Warwick, Coventry, UK Division of Translational and Systems Medicine, Warwick Medical School, University of Warwick, Coventry, UK Warwick Systems Biology Doctoral Training Centre, University of Warwick, Coventry, UK
| | - Anatoly Shmygol
- Division of Translational and Systems Medicine, Warwick Medical School, University of Warwick, Coventry, UK
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Bru-Mercier G, Gullam JE, Thornton S, Blanks AM, Shmygol A. Characterization of the tissue-level Ca2+ signals in spontaneously contracting human myometrium. J Cell Mol Med 2014; 16:2990-3000. [PMID: 22947266 PMCID: PMC4393727 DOI: 10.1111/j.1582-4934.2012.01626.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 08/28/2012] [Indexed: 11/30/2022] Open
Abstract
In the labouring uterus, millions of myocytes forming the complex geometrical structure of myometrium contract in synchrony to increase intrauterine pressure, dilate the cervix and eventually expel the foetus through the birth canal. The mechanisms underlying the precise coordination of contractions in human myometrium are not completely understood. In the present study, we have characterized the spatio-temporal properties of tissue-level [Ca(2+)](i) transients in thin slices of intact human myometrium. We found that the waveform of [Ca(2+)](i) transients and isotonic contractions recorded from thin slices was similar to the waveform of isometric contractions recorded from the larger strips in traditional organ bath experiments, suggesting that the spatio-temporal information obtained from thin slices is representative of the whole tissue. By comparing the time course of [Ca(2+)](i) transients in individual cells to that recorded from the bundles of myocytes we found that the majority of myocytes produce rapidly propagating long-lasting [Ca(2+)](i) transients accompanied by contractions. We also found a small number of cells showing desynchronized [Ca(2+)](i) oscillations that did not trigger contractions. The [Ca(2+)](i) oscillations in these cells were insensitive to nifedipine, but readily inhibited by the T-type Ca(2+) channel inhibitor NNC55-0396. In conclusion, our data suggest that the spread of [Ca(2+)](i) signals in human myometrium is achieved via propagation of long-lasting action potentials. The propagation was fast when action potentials propagated along bundles of myocytes and slower when propagating between the bundles of uterine myocytes.
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Brosens JJ, Salker MS, Teklenburg G, Nautiyal J, Salter S, Lucas ES, Steel JH, Christian M, Chan YW, Boomsma CM, Moore JD, Hartshorne GM, Sućurović S, Mulac-Jericevic B, Heijnen CJ, Quenby S, Koerkamp MJG, Holstege FCP, Shmygol A, Macklon NS. Uterine selection of human embryos at implantation. Sci Rep 2014; 4:3894. [PMID: 24503642 PMCID: PMC3915549 DOI: 10.1038/srep03894] [Citation(s) in RCA: 177] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 01/08/2014] [Indexed: 12/15/2022] Open
Abstract
Human embryos frequently harbor large-scale complex chromosomal errors that impede normal development. Affected embryos may fail to implant although many first breach the endometrial epithelium and embed in the decidualizing stroma before being rejected via mechanisms that are poorly understood. Here we show that developmentally impaired human embryos elicit an endoplasmic stress response in human decidual cells. A stress response was also evident upon in vivo exposure of mouse uteri to culture medium conditioned by low-quality human embryos. By contrast, signals emanating from developmentally competent embryos activated a focused gene network enriched in metabolic enzymes and implantation factors. We further show that trypsin, a serine protease released by pre-implantation embryos, elicits Ca2+ signaling in endometrial epithelial cells. Competent human embryos triggered short-lived oscillatory Ca2+ fluxes whereas low-quality embryos caused a heightened and prolonged Ca2+ response. Thus, distinct positive and negative mechanisms contribute to active selection of human embryos at implantation.
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Affiliation(s)
- Jan J Brosens
- Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratories, University Hospital, Coventry CV2 2DX, UK
| | - Madhuri S Salker
- 1] Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratories, University Hospital, Coventry CV2 2DX, UK [2] Institute of Reproductive and Developmental Biology, Imperial College London, Hammersmith Hospital, London W12 ONN, UK
| | - Gijs Teklenburg
- Department for Reproductive Medicine and Gynecology, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands
| | - Jaya Nautiyal
- Institute of Reproductive and Developmental Biology, Imperial College London, Hammersmith Hospital, London W12 ONN, UK
| | - Scarlett Salter
- Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratories, University Hospital, Coventry CV2 2DX, UK
| | - Emma S Lucas
- Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratories, University Hospital, Coventry CV2 2DX, UK
| | - Jennifer H Steel
- Institute of Reproductive and Developmental Biology, Imperial College London, Hammersmith Hospital, London W12 ONN, UK
| | - Mark Christian
- Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratories, University Hospital, Coventry CV2 2DX, UK
| | - Yi-Wah Chan
- Warwick Systems Biology Centre, University of Warwick, Coventry CV4 7AL, UK
| | - Carolien M Boomsma
- Department for Reproductive Medicine and Gynecology, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands
| | - Jonathan D Moore
- Warwick Systems Biology Centre, University of Warwick, Coventry CV4 7AL, UK
| | - Geraldine M Hartshorne
- Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratories, University Hospital, Coventry CV2 2DX, UK
| | - Sandra Sućurović
- Department of Physiology and Immunology, Medical School, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia
| | - Biserka Mulac-Jericevic
- Department of Physiology and Immunology, Medical School, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia
| | - Cobi J Heijnen
- Department for Reproductive Medicine and Gynecology, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands
| | - Siobhan Quenby
- Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratories, University Hospital, Coventry CV2 2DX, UK
| | - Marian J Groot Koerkamp
- Molecular Cancer Research, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands
| | - Frank C P Holstege
- Molecular Cancer Research, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands
| | - Anatoly Shmygol
- Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratories, University Hospital, Coventry CV2 2DX, UK
| | - Nick S Macklon
- 1] Department for Reproductive Medicine and Gynecology, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands [2] Division of Developmental Origins of Adult Diseases (DOHaD), University of Southampton, Coxford Road, Southampton SO16 5YA, UK
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Kuroda K, Venkatakrishnan R, James S, Šucurovic S, Mulac-Jericevic B, Lucas ES, Takeda S, Shmygol A, Brosens JJ, Quenby S. Elevated periimplantation uterine natural killer cell density in human endometrium is associated with impaired corticosteroid signaling in decidualizing stromal cells. J Clin Endocrinol Metab 2013; 98:4429-37. [PMID: 24025400 PMCID: PMC4207949 DOI: 10.1210/jc.2013-1977] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
BACKGROUND Decidualizing human endometrial stromal cells (HESCs) profoundly up-regulate 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1), the enzyme that converts inert cortisone to active cortisol. We postulated that the induction of a cortisol gradient upon decidualization of the periimplantation endometrium may impact on the uterine natural killer (uNK) cell population and on local expression of corticosteroid-dependent target genes. METHODS Midluteal endometrial biopsies (n = 55) were processed for uNK cell (CD56) analysis and primary HESC cultures. The cultures remained either untreated or were decidualized for 4 or 8 days. A tissue microarray was constructed from endometria with normal (n = 18) and elevated uNK cell (n = 18) scores. An abnormal uNK cell test was defined as greater than 5% CD56(+) cells in the subluminal stroma. RESULTS Increased uNK cell density was associated with lower endometrial expression of 11βHSD1 and mineralocorticoid receptor (MR) but not glucocorticoid receptor in vivo. Elevated uNK cell density also corresponded to impaired induction of key decidual markers (11βHSD1, prolactin, and insulin-like growth factor binding protein-1) and MR-dependent enzymes (dehydrogenase/reductase member 3 and retinol saturase) in differentiating HESC cultures. Increased uNK cell density in vivo was not associated with increased in vitro expression of either IL-15 or IL-11, two cytokines implicated in uNK cell regulation. CONCLUSIONS Elevated levels of uNK cells in the stroma underlying the surface epithelium are associated with inadequate cortisol biosynthesis by resident decidualizing cells and suboptimal induction of key MR-dependent enzymes involved in lipid biogenesis and the retinoid transport pathway. Our observations suggest that uNK cell testing identifies those women at risk of reproductive failure due to relative uterine cortisol deficiency.
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Affiliation(s)
- Keiji Kuroda
- Department of Reproductive Health, Clinical Science Research Institute, Warwick Medical School, University Hospital, Coventry CV2 2DX, United Kingdom.
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Sheldon RE, Baghdadi M, McCloskey C, Blanks AM, Shmygol A, van den Berg HA. Spatial heterogeneity enhances and modulates excitability in a mathematical model of the myometrium. J R Soc Interface 2013; 10:20130458. [PMID: 23843249 DOI: 10.1098/rsif.2013.0458] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The muscular layer of the uterus (myometrium) undergoes profound changes in global excitability prior to parturition. Here, a mathematical model of the myocyte network is developed to investigate the hypothesis that spatial heterogeneity is essential to the transition from local to global excitation which the myometrium undergoes just prior to birth. Each myometrial smooth muscle cell is represented by an element with FitzHugh-Nagumo dynamics. The cells are coupled through resistors that represent gap junctions. Spatial heterogeneity is introduced by means of stochastic variation in coupling strengths, with parameters derived from physiological data. Numerical simulations indicate that even modest increases in the heterogeneity of the system can amplify the ability of locally applied stimuli to elicit global excitation. Moreover, in networks driven by a pacemaker cell, global oscillations of excitation are impeded in fully connected and strongly coupled networks. The ability of a locally stimulated cell or pacemaker cell to excite the network is shown to be strongly dependent on the local spatial correlation structure of the couplings. In summary, spatial heterogeneity is a key factor in enhancing and modulating global excitability.
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Affiliation(s)
- Rachel E Sheldon
- MOAC Doctoral Training Centre, University of Warwick, Coventry CV4 7AL, UK.
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Aslanidi O, Atia J, Benson A, van den Berg H, Blanks A, Choi C, Gilbert S, Goryanin I, Hayes-Gill B, Holden A, Li P, Norman J, Shmygol A, Simpson N, Taggart M, Tong W, Zhang H. Towards a computational reconstruction of the electrodynamics of premature and full term human labour. Progress in Biophysics and Molecular Biology 2011; 107:183-92. [DOI: 10.1016/j.pbiomolbio.2011.07.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 07/05/2011] [Indexed: 01/02/2023]
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Gullam JE, Blanks AM, Thornton S, Shmygol A. Phase-plot analysis of the oxytocin effect on human myometrial contractility. Eur J Obstet Gynecol Reprod Biol 2009; 144 Suppl 1:S20-4. [DOI: 10.1016/j.ejogrb.2009.02.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Borisova L, Shmygol A, Wray S, Burdyga T. Evidence that a Ca2+ sparks/STOCs coupling mechanism is responsible for the inhibitory effect of caffeine on electro-mechanical coupling in guinea pig ureteric smooth muscle. Cell Calcium 2007; 42:303-11. [PMID: 17298845 DOI: 10.1016/j.ceca.2006.12.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Revised: 12/18/2006] [Accepted: 12/19/2006] [Indexed: 10/23/2022]
Abstract
Recent studies have highlighted the role of the sarcoplasmic reticulum (SR) in controlling excitability, Ca2+ signalling and contractility in smooth muscle. Caffeine, an agonist of ryanodine receptors (RyRs) on the SR has been previously shown to effect Ca2+ signalling but its effects on excitability and contractility are not so clear. We have studied the effects of low concentration of caffeine (1 mM) on Ca2+ signalling, action potential and contractility of guinea pig ureteric smooth muscle. Caffeine produced reversible inhibition of the action potentials, Ca2+ transients and phasic contractions evoked by electrical stimulation. It had no effect on the inward Ca2+ current or Ca2+ transient but increased the amplitude and the frequency of spontaneous transient outward currents (STOCs) in voltage clamped ureteric myocytes, suggesting Ca2+-activated K+ channels (BK) are affected by it. In isolated cells and cells in situ caffeine produced an increase in the frequency and the amplitude of Ca2+ sparks as well the number of spark discharging sites per cell. Inhibition of Ca2+ sparks by ryanodine (50 microM) or SR Ca2+-ATPase (SERCA) cyclopiazonic acid (CPA, 20 microM) or BKCa channels by iberiotoxin (200 nM) or TEA (1 mM), fully reversed the inhibitory effect of caffeine on Ca2+ transients and force evoked by electrical field stimulation (EFS). These data suggest that the inhibitory effect of caffeine on the action potential, Ca2+ transients and force in ureteric smooth muscle is caused by activation of Ca2+ sparks/STOCs coupling mechanism.
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Affiliation(s)
- L Borisova
- The Physiological Laboratory, University of Liverpool, Crown Street, Liverpool L69 3BX, UK
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Abstract
This article assesses the nature of the sarcoplasmic reticulum (SR) in uterine smooth muscle. Modern imagining techniques have revealed new information about the location and density of Ca storage and release. Release mechanisms, including IP(3) and Ca itself, via ryanodine receptors (RyR), as well as possible roles for cyclic ADP ribose, and the contribution of the SR to relaxation are detailed. The role of the SR Ca-ATPase in both decay of the Ca transient and maintaining Ca homeostasis is reviewed. Recent data on the role of local Ca signals from the SR in contributing to membrane excitability and contractility are discussed, along with interactions with ion channels in lipid microdomains.
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Affiliation(s)
- Susan Wray
- University of Liverpool, Department of Physiology, Crown Street, Liverpool L69 3BX, United Kingdom.
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Blanks AM, Zhao ZH, Shmygol A, Bru-Mercier G, Astle S, Thornton S. Characterization of the molecular and electrophysiological properties of the T-type calcium channel in human myometrium. J Physiol 2007; 581:915-26. [PMID: 17446221 PMCID: PMC1976399 DOI: 10.1113/jphysiol.2007.132126] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Rises in intracellular calcium are essential for contraction of human myometrial smooth muscle (HMSM) and hence parturition. The T-type calcium channel may play a role in this process. The aim was to investigate the role of the T-type calcium channel in HMSM by characterizing mRNA expression, protein localization, electrophysiological properties and function of the channel subunits Cav3.1(alpha1G), Cav3.2(alpha1H), and Cav3.3(alpha1I). QRT-PCR, immunohistochemistry, electrophysiology and invitro contractility were performed on human myometrial samples from term, preterm, labour and not in labour. QRT-PCR analysis of Cav3.1, Cav3.2 and Cav3.3 demonstrated expression of Cav3.1 and Cav3.2 with no significant change (P>0.05) associated with gestation or labour status. Immunohistochemistry localized Cav3.1 to myometrial and vascular smooth muscle cells whilst Cav3.2 localized to vascular endothelial cells and invading leucocytes. Voltage clamp studies demonstrated a T-type current in 55% of cells. Nickel block of T-type current was voltage sensitive (IC50 of 118.57+/-68.9 microM at -30 mV). Activation and inactivation curves of ICa currents in cells expressing T-type channels overlapped demonstrating steady state window currents at the resting membrane potential of myometrium at term. Current clamp analysis demonstrated that hyperpolarizing pulses to a membrane potential greater than -80 mV elicited rebound calcium spikes that were blocked reversibly by 100 microM nickel. Contractility studies demonstrated a reversible decrease in contraction frequency during application of 100 microM nickel (P<0.05). We conclude that the primary T-type subunit expressed in some MSMCs is Cav3.1. We found that application of 100 microM nickel to spontaneously contracting human myometrium reversibly slows contraction frequency.
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Affiliation(s)
- Andrew M Blanks
- Clinical Science Research Institute, Division of Clinical Sciences, Warwick Medical School, Coventry CV4 7AL, UK.
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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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Shmygol A, Blanks AM, Bru-Mercier G, Gullam JE, Thornton S. Control of uterine Ca2+ by membrane voltage: toward understanding the excitation-contraction coupling in human myometrium. Ann N Y Acad Sci 2007; 1101:97-109. [PMID: 17332087 DOI: 10.1196/annals.1389.031] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Myometrial contractility is a complex and dynamic physiological process that changes substantially during pregnancy and culminates in childbirth. Uterine contractions are initiated by transient rises in cytoplasmic Ca(2+) concentration ([Ca(2+)](i)), which in turn are triggered and controlled by myometrial action potentials. The sequence of events between the action potential generation and the contraction initiation is referred to as excitation-contraction coupling. Hormones and other physiologically active substances affect myometrial contractility by modulating different steps in the excitation-contraction coupling process. It is therefore imperative that we understand that process to understand the regulation of myometrial contractility. The complex action potentials generated by human myometrium result from the activity of many ion channels, transporters, and pumps. Two types of myometrial action potential waveform have been described in the literature: a plateau type and a spike type. Parameters of the myometrial [Ca(2+)](i) transients and contractions differ depending on the type of action potential that triggers them. Some aspects of the excitation-contraction coupling are unique to human myometrium and cannot be found in animal models; some others are common between many species. This article reviews the current state and discusses future directions of physiological research on human myometrial excitation-contraction coupling.
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Affiliation(s)
- Anatoly Shmygol
- Clinical Sciences Research Institute, The University of Warwick Medical School, Coventry, CV2 2DX, UK.
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Shmygol A, Noble K, Wray S. Depletion of membrane cholesterol eliminates the Ca2+-activated component of outward potassium current and decreases membrane capacitance in rat uterine myocytes. J Physiol 2007; 581:445-56. [PMID: 17331986 PMCID: PMC2075177 DOI: 10.1113/jphysiol.2007.129452] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Changes in membrane cholesterol content have potent effects on cell signalling and contractility in rat myometrium and other smooth muscles. We have previously shown that depletion of cholesterol with methyl-beta-cyclodextrin (MCD) disrupts caveolar microdomains. The aim of this work was to determine the mechanism underlying the increase in Ca(2+) signalling and contractility occurring in the myometrium with MCD. Patch clamp data obtained on freshly isolated myocytes from the uterus of day 19-21 rats showed that outward K(+) current was significantly reduced by MCD. Membrane capacitance was also reduced. Cholesterol-saturated MCD had no effect on the amplitude of outward current suggesting that the reduction in the outward current was due to cholesterol depletion induced by MCD rather than a direct inhibitory action of MCD on the K(+) channels. Confocal visualization of the membrane bound indicator Calcium Green C18, revealed internalization of the surface membrane with MCD treatment. Large conductance, Ca(2+)-sensitive K(+) channel proteins have been shown to localize to caveolae. When these channels were blocked by iberiotoxin outward current was significantly reduced in the uterine myocytes; MCD treatment reduced the density of outward current. Following reduction of outward current by MCD pretreatment, iberiotoxin was unable to produce any additional decrease in the current, suggesting a common target. MCD treatment also increased the amplitude and frequency of spontaneous rises in cytosolic Ca(2+) level ([Ca(2+)](i) transients) in isolated myocytes. In intact rat myometrium, MCD treatment increased Ca(2+) signalling and contractility, consistent with previous findings, and this effect was also found to be reduced by BK channel inhibition. These data suggest that (1) disruption of cholesterol-rich microdomains and caveolae by MCD leads to a decrease in the BK channel current thus increasing cell excitability, and (2) the changes in membrane excitability produced by MCD underlie the changes found in Ca(2+) signalling and uterine contractility.
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Affiliation(s)
- A Shmygol
- Clinical Sciences Research Institute, Warwick Medical School, University of Warwick, Coventry CV2 2DX, UK
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Blanks AM, Shmygol A, Thornton S. Regulation of Oxytocin Receptors and Oxytocin Receptor Signaling. Semin Reprod Med 2007; 25:52-9. [PMID: 17205423 DOI: 10.1055/s-2006-956775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The oxytocin (OT) -oxytocin receptor (OTR) system plays a key role in many aspects of mammalian reproduction as well as several other physiological processes such as bond pairing and cardiovascular homeostasis. To manifest these diverse physiological roles, the transcription and expression of the OTR is tightly regulated within reproductive, cardiovascular, and neuronal tissues. The expression of the OTR within the mammalian uterus is regulated during gestation with a peak at the day of delivery. The control of this dramatic increase in expression is mediated in rodent species by a combination of stretch, classical steroid hormone stimulation, and repression. In the human uterus events are less clear, although a prominent role for inflammatory-related rapid-response genes and novel transcription factors such as hMafF (human homologue of chicken musculoaponeurotic fibrosarcoma oncogene family protein F) have been put forward. In the uterus the potent uterotonic actions of OT are mediated by the OTR through G-protein activation to stimulate phospholipase C activity. The activated OTR increases contraction frequency and increases force by sensitizing the contractile apparatus of the myocytes to calcium. This review summarizes the current knowledge of the complex regulation of OTR transcription in the myometrium and the intracellular signaling mechanisms through which OT mediates its potent stimulatory effects.
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Affiliation(s)
- Andrew M Blanks
- Warwick Medical School, Clinical Sciences Research Institute, University Hospital of Coventry and Warwickshire, Coventry, United Kingdom.
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Abstract
Oxytocin is a small peptide hormone with multiple sites of action in human body. It regulates a large number of reproduction-related processes in all species. Particularly important is its ability to stimulate uterine contractility. This is achieved by multiple mechanisms involving sarcoplasmic reticulum Ca2+ release and sensitization of the contractile apparatus to Ca2+. In this paper, we review the data published by us and other groups on oxytocin-induced modulation of uterine contractility. We conclude that sensitization of contractile apparatus to Ca2+ is the most relevant physiological effect of oxytocin on human myometrium.
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Affiliation(s)
- Anatoly Shmygol
- Clinical Sciences Research Institute, Warwick Medical School, University of Warwick, Coventry, UK.
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Shmygol A, Wray S. Modulation of agonist-induced Ca2+ release by SR Ca2+ load: direct SR and cytosolic Ca2+ measurements in rat uterine myocytes. Cell Calcium 2005; 37:215-23. [PMID: 15670868 DOI: 10.1016/j.ceca.2004.10.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2004] [Revised: 10/02/2004] [Accepted: 10/12/2004] [Indexed: 10/26/2022]
Abstract
Release of Ca2+ from sarcoplasmic reticulum (SR) is one of the most important mechanisms of smooth muscle stimulation by a variety of physiologically active substances. Agonist-induced Ca2+ release is considered to be dependent on the Ca2+ content of the SR, although the mechanism underlying this dependence is unclear. In the present study, the effect of SR Ca2+ load on the amplitude of [Ca2+]i transients elicited by application of the purinergic agonist ATP was examined in uterine smooth muscle cells isolated from pregnant rats. Measurement of intraluminal Ca2+ level ([Ca2+]L) using a low affinity Ca indicator, mag-fluo-4, revealed that incubation of cells in a high-Ca2+ (10 mM) extracellular solution leads to a substantial increase in [Ca2+]L (SR overload). However, despite increased SR Ca2+ content this did not potentiate ATP-induced [Ca2+]i transients. Repetitive applications of ATP in the absence of extracellular Ca2+, as well as prolonged incubation in Ca2+-free solution without agonist, depleted the [Ca2+]L (SR overload). In contrast to overload, partial depletion of the SR substantially reduced the amplitude of Ca2+ release. ATP-induced [Ca2+]i transients were completely abolished when SR Ca2+ content was decreased below 80% of its normal value indicating a steep dependence of the IP3-mediated Ca2+ release on the Ca2+ load of the store. Our results suggest that in uterine smooth muscle cells decrease in the SR Ca2+ load below its normal resting level substantially reduces the IP3-mediated Ca2+ release, while Ca2+ overload of the SR has no impact on such release.
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Affiliation(s)
- Anatoly Shmygol
- Department of Physiology, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
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Duquette RA, Shmygol A, Vaillant C, Mobasheri A, Pope M, Burdyga T, Wray S. Vimentin-positive, c-kit-negative interstitial cells in human and rat uterus: a role in pacemaking? Biol Reprod 2004; 72:276-83. [PMID: 15385413 DOI: 10.1095/biolreprod.104.033506] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The mechanism underlying spontaneous pacemaker potential in the uterus is not clearly understood. Several spontaneously active smooth muscles have interstitial cells of Cajal (ICCs) or ICC-like cells. We therefore examined cells from freshly dispersed uterine muscle strips (from pregnant human and rat myometrium) and in situ uterine preparations to determine the cell types present. Both preparations revealed numerous ICC-like cells; they were multipolar, with spider-like projections and enlarged central regions. These cells were readily distinguished from uterine myocytes by their morphology and ultrastructure, i.e., no myofilaments, numerous mitochondria, caveolae, and filaments. In addition, the ICC-like cells were noncontractile. These cells were negative to c-kit, a classic marker for ICCs. They stained positive for the intermediate filament, vimentin, a marker for cells of mesenchymal origin but not differentiated myocytes. The ICC-like cells had a more or less stable resting membrane potential of -58+/-7 mV compared with smooth-muscle cells, -65+/-13 mV, and produced outward current in response to voltage clamp pulses. However, in contrast with uterine myocytes, inward currents were not observed. This is the first description of ICC-like cells in myometrium and their role in the uterus is discussed, as possible inhibitors of intrinsic smooth-muscle activity.
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Affiliation(s)
- R A Duquette
- Department of Physiology, The University of Liverpool, Liverpool, United Kingdom
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Abstract
Sarcoplasmic reticulum (SR) is abundant in uterine smooth muscle cells. The functional role of this organelle in the regulation of uterine myocytes is not fully understood. The data available in the literature suggest that SR plays a dual role: as a source of calcium and as a calcium sink shaping calcium transients produced by membrane depolarisation and uterotonic agonists. Advances in digital imaging techniques including confocal microscopy of isolated living cells, and the development of methods for direct measurement of intraluminal calcium, has triggered a substantial increase in the number of publications elucidating the role of intracellular stores in calcium signalling. In this paper we review the literature and our own work on the SR calcium store in uterine smooth muscle cells.
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Affiliation(s)
- Anatoly Shmygol
- Physiological Laboratory, University of Liverpool Crown Street, Liverpool L69 3BX, UK.
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Jones K, Shmygol A, Kupittayanant S, Wray S. Electrophysiological characterization and functional importance of calcium-activated chloride channel in rat uterine myocytes. Pflugers Arch 2004; 448:36-43. [PMID: 14740218 DOI: 10.1007/s00424-003-1224-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2003] [Accepted: 12/01/2003] [Indexed: 10/26/2022]
Abstract
In order to better understand the mechanisms underlying excitation of the uterus, we have elucidated the characteristics and functional importance of Ca(2+)-activated Cl(-) currents ( I(Cl-Ca)) in pregnant rat myometrium. In 101/320 freshly isolated myocytes, there was a slowly inactivating tail current (162+/-48 pA) upon repolarization following depolarising steps. This current has a reversal potential close to that for chloride, and was shifted when [Cl(-)] was altered. It was activated by Ca(2+) (but not Ba(2+)) entry through L-type Ca(2+) channels, enhanced by the Ca(2+) channel agonist Bay K8644 (2 microM), and inhibited by the Cl(-) channel blockers, niflumic acid (10 microM) and anthracene-9-carboxylic acid (9-AC, 100 microM). We therefore conclude that the pregnant rat myometrium contains Ca(2+)-activated Cl(-) channels producing inward current in ~30% of its cells. When these channels were inhibited by niflumic acid or 9-AC in intact tissues, the frequency of spontaneous contractions, was significantly reduced. Niflumic acid was also shown to inhibit oxytocin-induced contractions and Ca(2+) transients. Neither 9-AC nor niflumic acid had any effect on high-K-invoked contractions. Taken together these data suggest that Ca(2+)-activated Cl(-) channels are activated by Ca(2+) entry and play a functionally important role in myometrium, probably by contributing to membrane potential and firing frequency (pacemakers) in these cells.
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Affiliation(s)
- K Jones
- Department of Physiology, The University of Liverpool, Liverpool, L69 3BX, UK
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Abstract
Control of smooth muscle is vital for health. The major route to contraction is a rise in intracellular [Ca2+], determined by the entry and efflux of Ca2+ and release and re-uptake into the sarcoplasmic reticulum (SR). We review these processes in myometrium, to better understand excitation-contraction coupling and develop strategies for preventing problematic labours. The main mechanism of elevating [Ca2+] is voltage-gated L-type channels, due to pacemaker activity, which can be modulated by agonists. The rise of [Ca2+] produces Ca-calmodulin and activates MLCK. This phosphorylates myosin and force results. Without Ca2+ entry uterine contraction fails. The Na/Ca exchanger (NCX) and plasma membrane Ca-ATPase (PMCA) remove Ca2+, with contributions of 30% and 70% respectively. Studies with PMCA-4 knockout mice show that it contributes to reducing [Ca2+] and relaxation. The SR contributes to relaxation by vectorially releasing Ca2+ to the efflux pathways, and thereby increasing their rates. Agonists binding produces IP3 which can release Ca from the SR but inhibition of SR Ca2+ release increases contractions and Ca2+ transients. It is suggested that SR Ca2+ targets K+ channels on the surface membrane and thereby feedback to inhibit excitability and contraction.
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Affiliation(s)
- A Matthew
- Department of Physiology, The University of Liverpool, Liverpool L69 3BX, UK
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Monir-Bishty E, Pierce S, Kupittayanant S, Shmygol A, Wray S. The effects of metabolic inhibition on intracellular calcium and contractility of human myometrium. BJOG 2003. [DOI: 10.1111/j.1471-0528.2003.03103.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Monir-Bishty E, Pierce SJ, Kupittayanant S, Shmygol A, Wray S. The effects of metabolic inhibition on intracellular calcium and contractility of human myometrium. BJOG 2003; 110:1050-6. [PMID: 14664875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
OBJECTIVE Hypoxia occurs in the uterus during labour and may contribute to dysfunctional labours. We wanted to establish its effects on pregnant human myometrium and elucidate the mechanisms involved. DESIGN Scientific study. SETTING University Hospital and laboratories. POPULATION OR SAMPLE Term pregnant women. METHODS We measured contractions and intracellular [Ca(2+)] ([Ca(2+)](i)), in biopsies from term pregnant women undergoing elective caesarean section, and used cyanide to block oxidative phosphorylation. MAIN OUTCOME MEASURES Changes in contractility and calcium. RESULTS Although basal levels of [Ca(2+)](i) and tone rose, spontaneous and agonist-induced Ca(2+) transients and phasic contractions were rapidly reduced and abolished by cyanide. Neither stimulation of the uterus with oxytocin nor the Ca channel agonist, Bay K8644, prevented the changes produced by cyanide. The tonic force produced by depolarising the myometrium was also decreased by cyanide, but slowly recovered towards control levels, whereas [Ca(2+)](i) was maintained throughout. Similar data were obtained when nitrogen, rather than cyanide, was applied to the depolarised uterus. CONCLUSIONS Impairment of oxidative phosphorylation is a potent depressor of phasic activity in human myometrium, irrespective of how it is produced, and our data suggest its effects lie at and beyond the surface membrane. Stimulation of the hypoxic uterus was not effective, which may explain the unpredictability of oxytocin application in some dysfunctional labours.
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Burdyga T, Shmygol A, Eisner DA, Wray S. A new technique for simultaneous and in situ measurements of Ca2+ signals in arteriolar smooth muscle and endothelial cells. Cell Calcium 2003; 34:27-33. [PMID: 12767890 DOI: 10.1016/s0143-4160(03)00019-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We report here the first local and global Ca(2+) measurements made from in situ terminal arterioles. The advantages of the method are that there is minimal disturbance to the vessels, which retain their relationship to the tissue they are supplying (rat ureter) and the small size of vessel that can be studied. Good loading with the Ca(2+) indicator, Fluo-4 was obtained, and confocal sectioning through the tissue enabled vascular smooth muscle and endothelial cells to be clearly seen, along with red blood cells, nerve endings and the ureteric smooth muscle cells. We find the terminal arterioles to be extremely active, both spontaneously and in response to nor-adrenaline stimulation, with Ca(2+) sparks occurring in the vascular myocytes and Ca(2+) puffs in the endothelial cells. Even under resting conditions, endothelial cells produced oscillations and waves, which could pass from cell to cell, whereas the vascular myocytes only produced waves in response to agonist stimulation, and with no increase in the frequency of Ca(2+) sparks, and no spread from cell to cell. We compare our data to those obtained in dissected intact vessels and single cells. We conclude that this approach is a convenient and useful method for studying inter- and intracellular Ca(2+) signalling events and communication between cell types, particularly in very small vessels.
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MESH Headings
- Action Potentials/drug effects
- Action Potentials/physiology
- Aniline Compounds
- Animals
- Arterioles/cytology
- Arterioles/metabolism
- Calcium/analysis
- Calcium/metabolism
- Calcium Signaling/drug effects
- Calcium Signaling/physiology
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Histocytochemistry/instrumentation
- Histocytochemistry/methods
- Microscopy, Confocal/instrumentation
- Microscopy, Confocal/methods
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Norepinephrine/pharmacology
- Rats
- Ureter/blood supply
- Ureter/cytology
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
- Xanthenes
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Affiliation(s)
- T Burdyga
- The Physiological Laboratory, Department of Physiology, University of Liverpool, Crown Street, Liverpool L69 3BX, UK
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Abstract
In this review we discuss our current understanding of the cellular basis of uterine contractility, highlighting those areas requiring further study. It is clear that the basic processes of excitation-contraction coupling lie within the myometrial cell, and that these may be modified by agonists. Pacemaker activity, however, remains a mystery. The contribution of extracellular calcium entry to contraction is shown to be vital, whilst the role of the sarcoplasmic reticulum remains controversial. Much current experimental focus is on pathways controlling and regulating contraction, and we discuss sensitisation mechanisms and question their role in intact uterine preparations. Experimental Physiology (2001) 86.2, 239-246.
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Affiliation(s)
- S Wray
- The Physiological Laboratory, The University of Liverpool, Crown Street, Liverpool L69 3BX, UK
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