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Malik M, Roh M, England SK. Uterine contractions in rodent models and humans. Acta Physiol (Oxf) 2021; 231:e13607. [PMID: 33337577 PMCID: PMC8047897 DOI: 10.1111/apha.13607] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 12/07/2020] [Accepted: 12/11/2020] [Indexed: 12/18/2022]
Abstract
Aberrant uterine contractions can lead to preterm birth and other labour complications and are a significant cause of maternal morbidity and mortality. To investigate the mechanisms underlying dysfunctional uterine contractions, researchers have used experimentally tractable small animal models. However, biological differences between humans and rodents change how researchers select their animal model and interpret their results. Here, we provide a general review of studies of uterine excitation and contractions in mice, rats, guinea pigs, and humans, in an effort to introduce new researchers to the field and help in the design and interpretation of experiments in rodent models.
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Affiliation(s)
- Manasi Malik
- Center for Reproductive Health Sciences Department of Obstetrics and Gynecology Washington University School of Medicine St. Louis MO USA
| | - Michelle Roh
- Center for Reproductive Health Sciences Department of Obstetrics and Gynecology Washington University School of Medicine St. Louis MO USA
| | - Sarah K. England
- Center for Reproductive Health Sciences Department of Obstetrics and Gynecology Washington University School of Medicine St. Louis MO USA
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Wray S, Arrowsmith S. Uterine Excitability and Ion Channels and Their Changes with Gestation and Hormonal Environment. Annu Rev Physiol 2020; 83:331-357. [PMID: 33158376 DOI: 10.1146/annurev-physiol-032420-035509] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We address advances in the understanding of myometrial physiology, focusing on excitation and the effects of gestation on ion channels and their relevance to labor. This review moves through pioneering studies to exciting new findings. We begin with the myometrium and its myocytes and describe how excitation might initiate and spread in this myogenic smooth muscle. We then review each of the ion channels in the myometrium: L- and T-type Ca2+ channels, KATP (Kir6) channels, voltage-dependent K channels (Kv4, Kv7, and Kv11), twin-pore domain K channels (TASK, TREK), inward rectifier Kir7.1, Ca2+-activated K+ channels with large (KCNMA1, Slo1), small (KCNN1-3), and intermediate (KCNN4) conductance, Na-activated K channels (Slo2), voltage-gated (SCN) Na+ and Na+ leak channels, nonselective (NALCN) channels, the Na K-ATPase, and hyperpolarization-activated cation channels. We finish by assessing how three key hormones- oxytocin, estrogen, and progesterone-modulate and integrate excitability throughout gestation.
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Affiliation(s)
- Susan Wray
- Department of Women's and Children's Health, University of Liverpool, Liverpool L69 3BX, United Kingdom;
| | - Sarah Arrowsmith
- Department of Women's and Children's Health, University of Liverpool, Liverpool L69 3BX, United Kingdom;
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Role of potassium channels in female reproductive system. Obstet Gynecol Sci 2020; 63:565-576. [PMID: 32838485 PMCID: PMC7494774 DOI: 10.5468/ogs.20064] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 06/26/2020] [Indexed: 12/26/2022] Open
Abstract
Potassium channels are widely expressed in most types of cells in living organisms and regulate the functions of a variety of organs, including kidneys, neurons, cardiovascular organs, and pancreas among others. However, the functional roles of potassium channels in the reproductive system is less understood. This mini-review provides information about the localization and functions of potassium channels in the female reproductive system. Five types of potassium channels, which include inward-rectifying (Kir), voltage-gated (Kv), calcium-activated (KCa), 2-pore domain (K2P), and rapidly-gating sodium-activated (Slo) potassium channels are expressed in the hypothalamus, ovaries, and uterus. Their functions include the regulation of hormone release and feedback by Kir6.1 and Kir6.2, which are expressed in the luteal granulosa cells and gonadotropin-releasing hormone neurons respectively, and regulate the functioning of the hypothalamus–pituitary–ovarian axis and the production of progesterone. Both channels are regulated by subtypes of the sulfonylurea receptor (SUR), Kir6.1/SUR2B and Kir6.2/SUR1. Kv and Slo2.1 affect the transition from uterine quiescence in late pregnancy to the state of strong myometrial contractions in labor. Intermediate- and small-conductance KCa modulate the vasodilatation of the placental chorionic plate resistance arteries via the secretion of nitric oxide and endothelium-derived hyperpolarizing factors. Treatment with specific channel activators and inhibitors provides information relevant for clinical use that could help alter the functions of the female reproductive system.
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The Myometrium: From Excitation to Contractions and Labour. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1124:233-263. [PMID: 31183830 DOI: 10.1007/978-981-13-5895-1_10] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
We start by describing the functions of the uterus, its structure, both gross and fine, innervation and blood supply. It is interesting to note the diversity of the female's reproductive tract between species and to remember it when working with different animal models. Myocytes are the overwhelming cell type of the uterus (>95%) and our focus. Their function is to contract, and they have an intrinsic pacemaker and rhythmicity, which is modified by hormones, stretch, paracrine factors and the extracellular environment. We discuss evidence or not for pacemaker cells in the uterus. We also describe the sarcoplasmic reticulum (SR) in some detail, as it is relevant to calcium signalling and excitability. Ion channels, including store-operated ones, their contributions to excitability and action potentials, are covered. The main pathway to excitation is from depolarisation opening voltage-gated Ca2+ channels. Much of what happens downstream of excitability is common to other smooth muscles, with force depending upon the balance of myosin light kinase and phosphatase. Mechanisms of maintaining Ca2+ balance within the myocytes are discussed. Metabolism, and how it is intertwined with activity, blood flow and pH, is covered. Growth of the myometrium and changes in contractile proteins with pregnancy and parturition are also detailed. We finish with a description of uterine activity and why it is important, covering progression to labour as well as preterm and dysfunctional labours. We conclude by highlighting progress made and where further efforts are required.
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Alotaibi M, Kahlat K, Nedjadi T, Djouhri L. Effects of ZD7288, a hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker, on term-pregnant rat uterine contractility in vitro. Theriogenology 2017; 90:141-146. [DOI: 10.1016/j.theriogenology.2016.11.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Revised: 11/22/2016] [Accepted: 11/24/2016] [Indexed: 12/01/2022]
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Ryanodine receptor type 3 does not contribute to contractions in the mouse myometrium regardless of pregnancy. Pflugers Arch 2016; 469:313-326. [PMID: 27866274 DOI: 10.1007/s00424-016-1900-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 10/20/2016] [Accepted: 11/03/2016] [Indexed: 01/08/2023]
Abstract
Ryanodine receptor type 3 (RyR3) is expressed in myometrial smooth muscle cells (MSMCs). The short isoform of RyR3 is a dominant negative variant (DN-RyR3) and negatively regulates the functions of RyR2 and full-length (FL)-RyR3. DN-RyR3 has been suggested to function as a major RyR3 isoform in non-pregnant (NP) mouse MSMCs, and FL-RyR3 may also be upregulated during pregnancy (P). This increase in the FL-RyR3/DN-RyR3 ratio may contribute to the strong contractions by MSMCs for parturition. In the present study, spontaneous contractions by the myometrium in NP and P mice were highly susceptible to nifedipine but were not affected by ryanodine. Ca2+ image analyses under a voltage clamp revealed that the influx of Ca2+ through voltage-dependent Ca2+ channels did not cause the release of Ca2+ from the sarcoplasmic reticulum (SR). Cytosolic Ca2+ concentrations ([Ca2+]cyt) in MSMCs were not affected by caffeine. Despite the abundant expression of large conductance Ca2+-activated K+ channels in MSMCs, spontaneous transient outward currents were not observed in the resting state because of the substantive lack of Ca2+ sparks. Quantitative PCR and Western blot analyses indicated that DN-RyR3 was strongly expressed in the NP myometrium, while the expression of FL-RyR3 and DN-RyR3 was markedly reduced in the P myometrium. The messenger RNA (mRNA) expression of RyR2 and RyR1 was negligible in the NP and P myometria. Moreover, RyR3 knockout mice may become pregnant and deliver normally. Thus, we concluded that none of the RyR subtypes, including RyR3, play a significant role in the regulation of [Ca2+]cyt in or contractions by mouse MSMCs regardless of pregnancy.
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Bafor EE, Rowan EG, Edrada-Ebel R. Toward Understanding Myometrial Regulation: Metabolomic Investigation Reveals New Pathways of Oxytocin and Ritodrine Activity on the Myometrium. Reprod Sci 2016; 24:691-705. [DOI: 10.1177/1933719116667224] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Enitome E. Bafor
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, Scotland, United Kingdom
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, University of Benin, Benin, Edo State, Nigeria
| | - Edward G. Rowan
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, Scotland, United Kingdom
| | - RuAngelie Edrada-Ebel
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, Scotland, United Kingdom
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Song K, Zhong XG, Xia XM, Huang JH, Fan YF, Yuan RX, Xue NR, Du J, Han WX, Xu AM, Shen B. Orai1 forms a signal complex with SK3 channel in gallbladder smooth muscle. Biochem Biophys Res Commun 2015; 466:456-62. [PMID: 26367175 DOI: 10.1016/j.bbrc.2015.09.049] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 09/08/2015] [Indexed: 10/23/2022]
Abstract
Orai1 is one of the key components of store-operated Ca(2+) entry (SOCE) involved in diverse physiological functions. Orai1 may associate with other proteins to form a signaling complex. In the present study, we investigated the interaction between Orai1 and small conductance Ca(2+)-activated potassium channel 3 (SK3). With the use of RNA interference technique, we found that the SOCE and its associated membrane hyperpolarization were reduced while Orai1 was knocked down by a specific Orai1 siRNA in guinea pig gallbladder smooth muscle. However, with the use of isometric tension measurements, our results revealed that agonist-induced muscle contractility was significantly enhanced after Orai1 protein was knocked down or the tissue was treated by SK3 inhibitor apamin, but not affected by larger conductance Ca(2+)-activated potassium channel inhibitor iberiotoxin or intermediate conductance Ca(2+)-activated potassium channel inhibitor TRAM-34. In addition, in the presence of apamin, Orai1 siRNA had no additional effect on agonist-induced contraction. In coimmunoprecipitation experiment, SK3 and Orai1 pulled down each other. These data suggest that, Orai1 physically associated with SK3 to form a signaling complex in gallbladder smooth muscle. Ca(2+) entry via Orai1 activates SK3, resulting in membrane hyperpolarization in gallbladder smooth muscle. This hyperpolarizing effect of Orai1-SK3 coupling could serve to prevent excessive contraction of gallbladder smooth muscle in response to contractile agonists.
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Affiliation(s)
- Kai Song
- Department of Physiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui, 230032, China; Department of Gastrointestinal Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, 230022, China
| | - Xing-Guo Zhong
- Department of Surgery, Anhui Provincial Corps Hospital of Chinese People's Armed Police Force, Heifei, Anhui, 230041, China
| | - Xian-Ming Xia
- Department of Gastroenterology and Hepatology, The Fourth Affiliated Hospital of Anhui Medical University, Hefei, Anhui, 230032, China
| | - Jun-Hao Huang
- Department of Sports and Health, Guangzhou Sport University, Guangzhou, 510500, China
| | - Yi-Fei Fan
- Department of Physiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui, 230032, China
| | - Ren-Xiang Yuan
- Department of Physiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui, 230032, China
| | - Nai-Rui Xue
- Department of Physiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui, 230032, China
| | - Juan Du
- Department of Physiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui, 230032, China
| | - Wen-Xiu Han
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, 230022, China
| | - A-Man Xu
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, 230022, China; Department of Gastroenterology and Hepatology, The Fourth Affiliated Hospital of Anhui Medical University, Hefei, Anhui, 230032, China.
| | - Bing Shen
- Department of Physiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui, 230032, China.
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Roatesi I, Radu BM, Cretoiu D, Cretoiu SM. Uterine Telocytes: A Review of Current Knowledge. Biol Reprod 2015; 93:10. [PMID: 25695721 DOI: 10.1095/biolreprod.114.125906] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Accepted: 02/10/2015] [Indexed: 01/05/2023] Open
Abstract
Telocytes (TCs), a novel cell type, are briefly defined as interstitial cells with telopodes (Tps). However, a specific immunocytochemical marker has not yet been found; therefore, electron microscopy is currently the only accurate method for identifying TCs. TCs are considered to have a mesenchymal origin. Recently proteomic analysis, microarray-based gene expression analysis, and the micro-RNA signature clearly showed that TCs are different from fibroblasts, mesenchymal stem cells, and endothelial cells. The dynamics of Tps were also revealed, and some electrophysiological properties of TCs were described (such as membrane capacitance, input resistance, membrane resting potential, and absence of action potentials correlated with different ionic currents characteristics), which can be used to distinguish uterine TCs from smooth muscle cells (SMCs). Here, we briefly present the most recent findings on the characteristics of TCs and their functions in human pregnant and nonpregnant uteri.
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Affiliation(s)
- Iurie Roatesi
- Victor Babeş National Institute of Pathology, Bucharest, Romania Division of Cell Biology and Histology, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
| | - Beatrice Mihaela Radu
- Department of Neurological and Movement Sciences, University of Verona, Verona, Italy Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Dragos Cretoiu
- Victor Babeş National Institute of Pathology, Bucharest, Romania Division of Cell Biology and Histology, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
| | - Sanda Maria Cretoiu
- Victor Babeş National Institute of Pathology, Bucharest, Romania Division of Cell Biology and Histology, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
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Wray S, Burdyga T, Noble D, Noble K, Borysova L, Arrowsmith S. Progress in understanding electro-mechanical signalling in the myometrium. Acta Physiol (Oxf) 2015; 213:417-31. [PMID: 25439280 DOI: 10.1111/apha.12431] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 11/11/2014] [Accepted: 11/17/2014] [Indexed: 11/30/2022]
Abstract
In this review, we give a state-of-the-art account of uterine contractility, focussing on excitation-contraction (electro-mechanical) coupling (ECC). This will show how electrophysiological data and intracellular calcium measurements can be related to more modern techniques such as confocal microscopy and molecular biology, to advance our understanding of mechanical output and its modulation in the smooth muscle of the uterus, the myometrium. This new knowledge and understanding, for example concerning the role of the sarcoplasmic reticulum (SR), or stretch-activated K channels, when linked to biochemical and molecular pathways, provides a clearer and better informed basis for the development of new drugs and targets. These are urgently needed to combat dysfunctions in excitation-contraction coupling that are clinically challenging, such as preterm labour, slow to progress labours and post-partum haemorrhage. It remains the case that scientific progress still needs to be made in areas such as pacemaking and understanding interactions between the uterine environment and ion channel activity.
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Affiliation(s)
- S. Wray
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool Women's Hospital; Liverpool UK
| | - T. Burdyga
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool Women's Hospital; Liverpool UK
| | - D. Noble
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool Women's Hospital; Liverpool UK
| | - K. Noble
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool Women's Hospital; Liverpool UK
| | - L. Borysova
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool Women's Hospital; Liverpool UK
| | - S. Arrowsmith
- Department of Cellular and Molecular Physiology; Institute of Translational Medicine; University of Liverpool; Liverpool Women's Hospital; Liverpool UK
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Li Y, Lorca RA, Ma X, Rhodes A, England SK. BK channels regulate myometrial contraction by modulating nuclear translocation of NF-κB. Endocrinology 2014; 155:3112-22. [PMID: 24914944 PMCID: PMC4098006 DOI: 10.1210/en.2014-1152] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The large-conductance Ca(2+)-activated K(+) (BK) channel plays an essential role in maintaining uterine quiescence during pregnancy. Growing evidence has shown a link between the BK channel and bacterial lipopolysaccharide (LPS)-induced nuclear factor-κB (NF-κB) activation in macrophages. In the uterus, NF-κB activation plays an important role in inflammatory processes that lead to parturition. Our objective was to determine whether the BK channel regulates uterine contraction, in part, by modulating NF-κB translocation into the nucleus. We compared the effects of BK channel modulation to those of LPS on NF-κB nuclear translocation and contraction in an immortalized human myometrial cell line (human telomerase reverse transcriptase [hTERT]) and uterine myocytes. Our results showed that BK channel inhibitors paxilline and penitrem A induced translocation of NF-κB into the nucleus in both hTERT cells and uterine myocytes to a similar extent as LPS treatment, and LPS and paxilline similarly reduced BK channel currents. Conversely, neither BK channel openers nor blockade of the small conductance Ca(2+)-activated K(+) channel protein 3 had an effect on NF-κB translocation. Additionally, collagen-based assays showed that paxilline induced contraction of hTERT cells and uterine myocytes. This was dependent upon cyclooxygenase-2 activity. Moreover, paxilline-induced contractility and increased cyclooxygenase-2 expression both depended on availability of free NF-κB. This study suggests that BK channels regulate myometrial contraction, in part, by modulating nuclear translocation of NF-κB.
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Affiliation(s)
- Youe Li
- Center for Women's Reproductive Sciences Research, Department of Obstetrics and Gynecology, Basic Science Division, Washington University in St Louis, St Louis, Missouri 63110
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Store-operated Ca²⁺ entry and depolarization explain the anomalous behaviour of myometrial SR: effects of SERCA inhibition on electrical activity, Ca²⁺ and force. Cell Calcium 2014; 56:188-94. [PMID: 25084623 PMCID: PMC4169181 DOI: 10.1016/j.ceca.2014.07.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 07/03/2014] [Accepted: 07/09/2014] [Indexed: 11/23/2022]
Abstract
SERCA pump inhibition by CPA caused membrane depolarization, activation of action potentials, Ca2+ spikes and force. Depletion of Ca2+ store by agonists leads to membrane depolarization and activation of electrical and mechanical activity. Ca2+ release/Ca2+ entry coupling is playing a key role in control of spontaneous electrical and mechanical activity in rat pregnant myometrium.
In the myometrium SR Ca2+ depletion promotes an increase in force but unlike several other smooth muscles, there is no Ca2+ sparks-STOCs coupling mechanism to explain this. Given the importance of the control of contractility for successful parturition, we have examined, in pregnant rat myometrium, the effects of SR Ca2+-ATPase (SERCA) inhibition on the temporal relationship between action potentials, Ca2+ transients and force. Simultaneous recording of electrical activity, calcium and force showed that SERCA inhibition, by cyclopiazonic acid (CPA 20 μM), caused time-dependent changes in excitability, most noticeably depolarization and elevations of baseline [Ca2+]i and force. At the onset of these changes there was a prolongation of the bursts of action potentials and a corresponding series of Ca2+ spikes, which increased the amplitude and duration of contractions. As the rise of baseline Ca2+ and depolarization continued a point was reached when electrical and Ca2+ spikes and phasic contractions ceased, and a maintained, tonic force and Ca2+ was produced. Lanthanum, a non-selective blocker of store-operated Ca2+ entry, but not the L-type Ca2+ channel blocker nifedipine (1–10 μM), could abolish the maintained force and calcium. Application of the agonist, carbachol, produced similar effects to CPA, i.e. depolarization, elevation of force and calcium. A brief, high concentration of carbachol, to cause SR Ca2+ depletion without eliciting receptor-operated channel opening, also produced these results. The data obtained suggest that in pregnant rats SR Ca2+ release is coupled to marked Ca2+ entry, via store operated Ca2+ channels, leading to depolarization and enhanced electrical and mechanical activity.
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Rosenbaum ST, Svalø J, Nielsen K, Larsen T, Jørgensen JC, Bouchelouche P. Immunolocalization and expression of small-conductance calcium-activated potassium channels in human myometrium. J Cell Mol Med 2014; 16:3001-8. [PMID: 22947283 PMCID: PMC4393728 DOI: 10.1111/j.1582-4934.2012.01627.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 08/28/2012] [Indexed: 11/28/2022] Open
Abstract
Small-conductance calcium-activated potassium (SK3) channels have been detected in human myometrium and we have previously shown a functional role of SK channels in human myometrium in vitro. The aims of this study were to identify the precise localization of SK3 channels and to quantify SK3 mRNA expression in myometrium from pregnant and non-pregnant women. Myometrial biopsies were obtained from pregnant (n = 11) and non-pregnant (n = 11) women. The expression of SK3 channels was assessed using immunohistochemistry and SK3 mRNA was determined by qRT-PCR. In non-pregnant myometrium SK3 immunoreactivity was observed in CD34 positive (CD34(+)) interstitial Cajal-like cells (ICLC), now called telocytes. Although CD34(+) cells were also present in pregnant myometrium, they lacked SK3 immunoreactivity. Furthermore, the immunohistochemical results showed that SK3 expression in vascular endothelium was similar between the two groups. CD117 immunoreactivity was only detected in small round cells that resemble mast cells. Compared to non-pregnant myometrium we found significantly less SK3 mRNA in pregnant myometrium. We demonstrate that SK3 channels are localized solely in CD34(+) cells and not in smooth muscle cells, and that the molecular expression of SK3 channels is higher in non-pregnant compared to pregnant myometrium. On the basis of our previous study and the present findings, we propose that SK3 activators reduce contractility in human myometrium by modulating telocyte function. This is the first report to provide evidence for a possible role of SK3 channels in human uterine telocytes.
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Affiliation(s)
- Sofia T Rosenbaum
- Department of Gynaecology and Obstetrics, Holbaek Hospital, Holbaek, Denmark.
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Expression of the small conductance Ca²⁺-activated potassium channel subtype 3 (SK3) in rat uterus after stimulation with 17β-estradiol. PLoS One 2014; 9:e87652. [PMID: 24505302 PMCID: PMC3914860 DOI: 10.1371/journal.pone.0087652] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 12/31/2013] [Indexed: 01/15/2023] Open
Abstract
Preterm births accounts for roughly 9% of all births worldwide and can have detrimental or even lethal consequences for the infant. However to develop new treatment that will lower the rate of preterm births, more knowledge is required on the factors contributing to the contraction and relaxation of the myometrium. The small conductance Ca2+-activated potassium channel subtype 3 (SK3) has been identified in the myometrium of several species including humans, mice and rats, but with great inter species variation of the expression pattern and regulation. The aim of this study was to investigate the expression of SK3 in the uterus of rats stimulated with 17β-estradiol and progesterone in order to get an in depth understanding of the rat uterine SK3. Using immunohistochemistry SK3 was localized to the glandular and luminal endometrial lamina epitheliali. Furthermore, a weak signal was observed in the myometrium. Using Western blot the protein level of SK3 was found to increase in uteri from animals treated with 17β-estradiol, an effect that was not reflected at the mRNA level. The levels of mRNA for SK3 were significantly lower in the uterus of 17β-estradiol-treated animals than in the uterus of ovariectomized animals. We conclude that the SK channels are present in the endometrial epithelium, and possibly also in the myometrium of the rat uterus. Furthermore, the hormonal effect on SK3 caused by 17β-estradiol includes divergent regulation at mRNA and protein levels.
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Abstract
Ion channels play a key role in defining myometrial contractility. Modulation of ion channel populations is proposed to underpin gestational changes in uterine contractility associated with the transition from uterine quiescence to active labour. Of the myriad ion channels present in the uterus, this article will focus upon potassium channels encoded by the KCNQ genes and ether-à-go-go-related (ERG) genes. Voltage-gated potassium channels encoded by KCNQ and ERG (termed Kv7 and Kv11, respectively) are accepted as major determinants of neuronal excitability and the duration of the cardiac action potential. However, there is now growing appreciation that these ion channels have a major functional impact in vascular and non-vascular smooth muscle. Moreover, Kv7 channels may be potential therapeutic targets for the treatment of preterm labour.
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Affiliation(s)
- Iain A Greenwood
- * St George's Medical School, Division of Biomedical Sciences, London SW17 0RE, UK.
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Young RC, Goloman G. Phasic oscillations of extracellular potassium (K(o)) in pregnant rat myometrium. PLoS One 2013; 8:e65110. [PMID: 23724127 PMCID: PMC3665820 DOI: 10.1371/journal.pone.0065110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 04/25/2013] [Indexed: 11/19/2022] Open
Abstract
K-sensitive microelectrodes were used to measure K(+) within the extracellular space (K(o)) of pregnant rat myometrium. Contractile activity was monitored by measuring either force or bioelectrical signals. Single and double-barreled electrodes were used. Double-barreled electrodes allowed monitoring of electrical activity 15 microns from the site of K(o) measurement. From double-barreled electrode experiments, the bioelectrical burst started first, and then K(o) began to rise 0.6 ± 0.1 seconds later. This delay indicates that K(+) leaves the cells in response to local electrical activity rather than vice versa. Four control experiments were performed to assess the influence of electrical artifacts caused by tissue motion on K(o) values. When observed, artifacts were negative and transient, and hence would result in an underestimation of K(o) rises. Artifacts were minimized when tissue motion was minimized by fixing the tissue at both ends. At 37°C, 7 single barreled experiments and 45 contractions were analyzed. Resting K(o) was within 1 mM of bath K(+) (5 mM) at the beginning and end of the experiments. K(o) rose during the contraction, fell after the completion of the contraction, and normalized before the next contraction began. Peak K(o) values observed during force production were 18.8 ± 5.9 mM, a value high enough to modulate tissue-level electrical activity. K(o) required 15.7 ± 2.8 seconds to normalize halfway (t50). Six experiments expressing 38 contractions were performed at 24°C. The contraction period was longer at 24°C. Values for peak K(o) (26.2 ± 9.9 mM) and t50 (29.8±16.2 sec) were both larger than at 37°C (p<0.0003 for both). The direct relationships between peak K(o), t50 and the contraction period, suggest elevations in K(o) may modulate contraction frequency. The myometrial interstitial space appears to be functionally important, and K(o) metabolism may participate in cell-cell interactions.
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Affiliation(s)
- Roger C Young
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Vermont, Burlington, Vermont, United States of America.
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Zhu R, Hu XQ, Xiao D, Yang S, Wilson SM, Longo LD, Zhang L. Chronic hypoxia inhibits pregnancy-induced upregulation of SKCa channel expression and function in uterine arteries. Hypertension 2013; 62:367-74. [PMID: 23716582 DOI: 10.1161/hypertensionaha.113.01236] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Small-conductance Ca(2+)-activated K(+) (SKCa) channels are crucial in regulating vascular tone and blood pressure. The present study tested the hypothesis that SKCa channels play an important role in uterine vascular adaptation in pregnancy, which is inhibited by chronic hypoxia during gestation. Uterine arteries were isolated from nonpregnant and near-term pregnant sheep maintained at sea level (≈300 m) or exposed to high-altitude (3801 m) hypoxia for 110 days. Immunohistochemistry revealed the presence of SKCa channels type 2 (SK2) and type 3 (SK3) in both smooth muscles and endothelium of uterine arteries. The expression of SK2 and SK3 channels was significantly increased during pregnancy, which was inhibited by chronic hypoxia. In normoxic animals, both SKCa channel opener NS309 and a large-conductance (BKCa) channel opener NS1619 relaxed norepinephrine-contracted uterine arteries in pregnant but not nonpregnant sheep. These relaxations were inhibited by selective SKCa and BKCa channel blockers, respectively. NS309-induced relaxation was largely endothelium-independent. In high-altitude hypoxic animals, neither NS1691 nor NS309 produced significant relaxation of uterine arteries in either nonpregnant or pregnant sheep. Similarly, the role of SKCa channels in regulating the myogenic reactivity of uterine arteries in pregnant animals was abrogated by chronic hypoxia. Accordingly, the enhanced SKCa channel activity in uterine arterial myocytes of pregnant animals was ablated by chronic hypoxia. The findings suggest a novel mechanism of SKCa channels in regulating myogenic adaptation of uterine arteries in pregnancy and in the maladaptation of uteroplacental circulation caused by chronic hypoxia during gestation.
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Affiliation(s)
- Ronghui Zhu
- Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University, School of Medicine, Loma Linda, CA 92350, USA
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Turton P, Arrowsmith S, Prescott J, Ballard C, Bricker L, Neilson J, Wray S. A comparison of the contractile properties of myometrium from singleton and twin pregnancies. PLoS One 2013; 8:e63800. [PMID: 23671701 PMCID: PMC3646038 DOI: 10.1371/journal.pone.0063800] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 04/05/2013] [Indexed: 12/02/2022] Open
Abstract
Objective Over half of twin pregnancies in US and UK deliver prematurely but the reasons for this are unclear. The contractility of myometrium from twin pregnancies has not been directly investigated. The objective of this research was to determine if there are differences in the contractile activity and response to oxytocin, between myometrium from singleton and twin pregnancies, across a range of gestational ages. Furthermore, we wished to determine if contractile activity correlates with increasing level of stretch, using neonatal birth weights as a marker of uterine stretch. Methods This was an in vitro, laboratory based study of myometrial contractility in women pregnant with one or two babies, using biopsies obtained from non-labouring women undergoing Caesarean section. Spontaneous, oxytocin-stimulated and depolarization induced contractile activity was compared. Results Direct measurements of myometrial contractility under controlled conditions show that the frequency of contractions and responses to oxytocin are significantly increased in twins compared to singletons. The duration of contraction however was significantly reduced. We find that contractile activity correlates with increasing levels of stretch, using neonatal birth weights as a surrogate for uterine stretch, with response to oxytocin being significantly positively correlated with birth weight. Conclusions We have found significant differences in contractile properties between myometrium from singleton and twin pregnancies and that increasing uterine stretch can alter the contractile properties of myometrium. We discuss the implication of these findings to preterm delivery and future studies.
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Affiliation(s)
- Peter Turton
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Sarah Arrowsmith
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Jonathan Prescott
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Celia Ballard
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Leanne Bricker
- Liverpool Women's NHS Foundation Trust, Liverpool, United Kingdom
| | - James Neilson
- Department of Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, United Kingdom
| | - Susan Wray
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
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Rosenbaum ST, Larsen T, Joergensen JC, Bouchelouche PN. Relaxant effect of a novel calcium-activated potassium channel modulator on human myometrial spontaneous contractility in vitro. Acta Physiol (Oxf) 2012; 205:247-54. [PMID: 22099068 DOI: 10.1111/j.1748-1716.2011.02384.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM To investigate the effect of 4,5-dichloro-1,3-diethyl-1,3-dihydro-benzoimidazol-2-one (NS4591), a novel SK/IK channels positive modulator, on human myometrial activity. METHODS Organ bath studies were performed on myometrial preparations obtained from women undergoing elective caesarean section at term (N = 11) or hysterectomy (N = 11). NS4591 was added cumulatively in the concentration range of 0.3-30 μm. In separate experiments, the effects of pre-incubation of muscle preparation with the SK or IK channel blockers apamin (1 μm) and TRAM34 (10 μm) on the outcomes of NS4591 were evaluated. Simultaneous vehicle controls were performed for all experiments. The effects of drugs were studied on spontaneous contractions. RESULTS NS4591 exerted an inhibitory effect on myometrial contractions in muscle strips from non-pregnant and pregnant women. The contractility in non-pregnant and pregnant myometrium was reduced to the following values respectively: amplitude 20.65 ± 7.38% (P < 0.001) and 42.85 ± 11.04% (P < 0.05) and area under the curve 11.72 ± 7.39% (P < 0.001) and 34.84 ± 10.50% (P < 0.001) and are reflective of 30 μm NS4591 compared to vehicle control. In non-pregnant tissue, apamin partially reduced the inhibitory effects of NS4591, but we observed relaxation mediated by NS4591 despite pre-incubation with TRAM34. In contrast, in pregnant tissue, neither apamin nor TRAM34 could reverse the relaxatory effects of NS4591. CONCLUSION Our findings imply that SK/IK channels are present and functional in myometrium from pregnant and non-pregnant women. The SK/IK channel-positive modulator NS4591 exerts relaxation of human myometrium in vitro, and this may have implications for the clinical management of preterm labour.
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Affiliation(s)
- S T Rosenbaum
- Department of Gynecology and Obstetrics, Holbaek Hospital, Holbaek, Denmark.
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Zeng XC, Zhang L, Nie Y, Luo X. Identification and molecular characterization of three new K+-channel specific toxins from the Chinese scorpion Mesobuthus martensii Karsch revealing intronic number polymorphism and alternative splicing in duplicated genes. Peptides 2012; 34:311-23. [PMID: 22230549 DOI: 10.1016/j.peptides.2011.12.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 12/21/2011] [Accepted: 12/21/2011] [Indexed: 11/23/2022]
Abstract
K(+)-channel specific toxins from scorpions are powerful probes used in the structural and functional characterization of different subfamilies of K(+)-channels which are thought to be the most diverse ion channels. However, only a limited number of K(+)-channel toxins have been identified from scorpions so far; moreover, little is known about the mechanisms for the generation of a combinatorial peptide library in a venom gland of a scorpion. Here, we identified and characterized three new K(+)-channel toxin-like peptides from the scorpion Mesobuthus martensii Karsch, which were referred to as BmKcug1, BmKcug2 and BmKcugx, respectively. BmKcug1 and BmKcug2 are two new members of α-KTx1 subfamily, and have been classified as α-KTx1.14 and α-KTx1.15, respectively. BmKcugx represents a new subfamily of K(+)-channel specific toxins which was classified into α-KTx22. BmKcugx was thus classified as α-KTx22.1. Genomic analysis demonstrated that BmKcugx gene has two exons interrupted by an intron inserted in the signal peptide encoding region, whereas BmKcug1a (a close homologue of BmKcug1)/BmKcug2 gene was interrupted by two introns, located within the 5'UTR of the gene and in the signal peptide encoding region, respectively. Transcriptomic analysis for the venom glands of M. martensii Karsch indicated that the abundances of the transcripts of BmKcug1a and BmKcug2 are much higher than that of BmKcugx; it suggests that the intron in 5'UTR could markedly increase the expression level of the K(+)-channel toxins. Alignment of the genomic sequences of BmKcug1a and BmKcug2 revealed that an alternative splicing event occurred at the intron 1-exon 2 junction in the 5'UTR of BmKcug2 transcript.
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Affiliation(s)
- Xian-Chun Zeng
- Department of Biological Science and Technology, School of Environmental Studies & State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Wuhan), Wuhan 430074, China.
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Al-Qahtani S, Heath A, Quenby S, Dawood F, Floyd R, Burdyga T, Wray S. Diabetes is associated with impairment of uterine contractility and high Caesarean section rate. Diabetologia 2012; 55:489-98. [PMID: 22101974 PMCID: PMC3245824 DOI: 10.1007/s00125-011-2371-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Accepted: 10/13/2011] [Indexed: 01/23/2023]
Abstract
AIMS/HYPOTHESIS The prevalence of births worldwide complicated by diabetes mellitus is increasing. In the UK, for example, <25% of diabetic women have a non-instrumental vaginal delivery. Strikingly, more than half the Caesarean sections (CS) in these patients are non-elective, but the reasons for this are not understood. We have tested the hypothesis that poor myometrial contractility as a consequence of the disease contributes to this high CS rate. METHODS We compared spontaneous, high K depolarisation and oxytocin-induced contractions from diabetic and matched control patients having an elective CS. To investigate the mechanism of any differences we measured intracellular Ca, and performed western blotting and compared the tissues histologically. RESULTS There was significantly decreased contraction amplitude and duration in uteri from diabetic compared with control patients, even when possible confounders such as BMI were analysed. Reduced intracellular calcium signals and expression of calcium entry channels were found in uteruses from diabetic patients, which, along with a reduction in muscle content found on histological examination, could explain the reduced force. Myometrium from diabetic patients was responsive to oxytocin, but still did not reach the levels found in non-diabetic patients. CONCLUSIONS/INTERPRETATIONS These are the first data investigating myometrium in diabetic patients and they support the hypothesis that there is poorer contractility even in the presence of oxytocin. The underlying mechanism is related to reduced Ca channel expression and intracellular calcium signals and a decrease in muscle mass. We conclude that these factors significantly contribute to the increased emergency CS rate in diabetic patients.
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Affiliation(s)
- S. Al-Qahtani
- Department of Molecular and Cellular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX UK
- Department of Physiology, Medical College, Jazan University, Jazan, Kingdom of Saudi Arabia
| | - A. Heath
- Department of Molecular and Cellular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX UK
| | - S. Quenby
- Liverpool Women’s Hospital, University of Liverpool, Liverpool, UK
- Present Address: Clinical Sciences Research Institute, University of Warwick, Coventry, UK
| | - F. Dawood
- Liverpool Women’s Hospital, University of Liverpool, Liverpool, UK
| | - R. Floyd
- Department of Molecular and Cellular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX UK
| | - T. Burdyga
- Department of Molecular and Cellular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX UK
| | - S. Wray
- Department of Molecular and Cellular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX UK
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Skarra DV, Cornwell T, Solodushko V, Brown A, Taylor MS. CyPPA, a positive modulator of small-conductance Ca(2+)-activated K(+) channels, inhibits phasic uterine contractions and delays preterm birth in mice. Am J Physiol Cell Physiol 2011; 301:C1027-35. [PMID: 21795518 DOI: 10.1152/ajpcell.00082.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Organized uterine contractions, including those necessary for parturition, are dependent on calcium entry through voltage-gated calcium channels in myometrial smooth muscle cells. Recent evidence suggests that small-conductance Ca(2+)-activated potassium channels (K(Ca)2), specifically isoforms K(Ca)2.2 and 2.3, may control these contractions through negative feedback regulation of Ca(2+) entry. We tested whether selective pharmacologic activation of K(Ca)2.2/2.3 channels might depress uterine contractions, providing a new strategy for preterm labor intervention. Western blot analysis and immunofluorescence microscopy revealed expression of both K(Ca)2.2 and K(Ca)2.3 in the myometrium of nonpregnant (NP) and pregnant (gestation day 10 and 16; D10 and D16, respectively) mice. Spontaneous phasic contractions of isolated NP, D10, and D16 uterine strips were all suppressed by the K(Ca)2.2/2.3-selective activator CyPPA in a concentration-dependent manner. This effect was antagonized by the selective K(Ca)2 inhibitor apamin. Whereas CyPPA sensitivity was reduced in D10 and D16 versus NP strips (pIC(50) 5.33 ± 0.09, 4.64 ± 0.03, 4.72 ± 0.10, respectively), all contractions were abolished between 30 and 60 μM. Blunted contractions were associated with CyPPA depression of spontaneous Ca(2+) events in myometrial smooth muscle bundles. Augmentation of uterine contractions with oxytocin or prostaglandin F(2α) did not reduce CyPPA sensitivity or efficacy. Finally, in an RU486-induced preterm labor model, CyPPA significantly delayed time to delivery by 3.4 h and caused a 2.5-fold increase in pup retention. These data indicate that pharmacologic stimulation of myometrial K(Ca)2.2/2.3 channels effectively suppresses Ca(2+)-mediated uterine contractions and delays preterm birth in mice, supporting the potential utility of this approach in tocolytic therapies.
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Affiliation(s)
- Dana V Skarra
- Department of Physiology, University of South Alabama College of Medicine, Mobile, AL 36688, USA
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Tong WC, Choi CY, Karche S, Holden AV, Zhang H, Taggart MJ. A computational model of the ionic currents, Ca2+ dynamics and action potentials underlying contraction of isolated uterine smooth muscle. PLoS One 2011; 6:e18685. [PMID: 21559514 PMCID: PMC3084699 DOI: 10.1371/journal.pone.0018685] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 03/15/2011] [Indexed: 11/18/2022] Open
Abstract
Uterine contractions during labor are discretely regulated by rhythmic action potentials (AP) of varying duration and form that serve to determine calcium-dependent force production. We have employed a computational biology approach to develop a fuller understanding of the complexity of excitation-contraction (E-C) coupling of uterine smooth muscle cells (USMC). Our overall aim is to establish a mathematical platform of sufficient biophysical detail to quantitatively describe known uterine E-C coupling parameters and thereby inform future empirical investigations of physiological and pathophysiological mechanisms governing normal and dysfunctional labors. From published and unpublished data we construct mathematical models for fourteen ionic currents of USMCs: currents (L- and T-type), current, an hyperpolarization-activated current, three voltage-gated currents, two -activated current, -activated current, non-specific cation current, - exchanger, - pump and background current. The magnitudes and kinetics of each current system in a spindle shaped single cell with a specified surface area∶volume ratio is described by differential equations, in terms of maximal conductances, electrochemical gradient, voltage-dependent activation/inactivation gating variables and temporal changes in intracellular computed from known fluxes. These quantifications are validated by the reconstruction of the individual experimental ionic currents obtained under voltage-clamp. Phasic contraction is modeled in relation to the time constant of changing . This integrated model is validated by its reconstruction of the different USMC AP configurations (spikes, plateau and bursts of spikes), the change from bursting to plateau type AP produced by estradiol and of simultaneous experimental recordings of spontaneous AP, and phasic force. In summary, our advanced mathematical model provides a powerful tool to investigate the physiological ionic mechanisms underlying the genesis of uterine electrical E-C coupling of labor and parturition. This will furnish the evolution of descriptive and predictive quantitative models of myometrial electrogenesis at the whole cell and tissue levels.
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Affiliation(s)
- Wing-Chiu Tong
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
- Maternal and Fetal Health Research Centre, St. Mary's Hospital, University of Manchester, Manchester, United Kingdom
| | - Cecilia Y. Choi
- School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
| | - Sanjay Karche
- School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
| | - Arun V. Holden
- Institute of Membrane and System Biology, University of Leeds, Leeds, United Kingdom
| | - Henggui Zhang
- School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
- * E-mail: (HZ); (MT)
| | - Michael J. Taggart
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
- Maternal and Fetal Health Research Centre, St. Mary's Hospital, University of Manchester, Manchester, United Kingdom
- * E-mail: (HZ); (MT)
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