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Li XT. The modulation of potassium channels by estrogens facilitates neuroprotection. Front Cell Dev Biol 2022; 10:998009. [PMID: 36393851 PMCID: PMC9643774 DOI: 10.3389/fcell.2022.998009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 10/11/2022] [Indexed: 08/31/2023] Open
Abstract
Estrogens, the sex hormones, have the potential to govern multiple cellular functions, such as proliferation, apoptosis, differentiation, and homeostasis, and to exert numerous beneficial influences for the cardiovascular system, nervous system, and bones in genomic and/or non-genomic ways. Converging evidence indicates that estrogens serve a crucial role in counteracting neurodegeneration and ischemic injury; they are thereby being considered as a potent neuroprotectant for preventing neurological diseases such as Alzheimer's disease and stroke. The underlying mechanism of neuroprotective effects conferred by estrogens is thought to be complex and multifactorial, and it remains obscure. It is well established that the K+ channels broadly expressed in a variety of neural subtypes determine the essential physiological features of neuronal excitability, and dysfunction of these channels is closely associated with diverse brain deficits, such as ataxia and epilepsy. A growing body of evidence supports a neuroprotective role of K+ channels in malfunctions of nervous tissues, with the channels even being a therapeutic target in clinical trials. As multitarget steroid hormones, estrogens also regulate the activity of distinct K+ channels to generate varying biological actions, and accumulated data delineate that some aspects of estrogen-mediated neuroprotection may arise from the impact on multiple K+ channels, including Kv, BK, KATP, and K2P channels. The response of these K+ channels after acute or chronic exposure to estrogens may oppose pathological abnormality in nervous cells, which serves to extend our understanding of these phenomena.
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Affiliation(s)
- Xian-Tao Li
- School of Medicine, Guizhou University, Guiyang, China
- Department of Neuroscience, South-Central University for Nationalities, Wuhan, China
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2
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Kuan KKW, Saunders PTK. Female Reproductive Systems: Hormone Dependence and Receptor Expression. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1390:21-39. [PMID: 36107311 DOI: 10.1007/978-3-031-11836-4_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
The female reproductive system which consists of the ovaries, uterus (myometrium, endometrium), Fallopian tubes, cervix and vagina is exquisitely sensitive to the actions of steroid hormones. The ovaries play a key role in the synthesis of bioactive steroids (oestrogens, androgens, progestins) that act both within the tissue (intracrine/paracrine) as well as on other reproductive organs following release into the blood stream (endocrine action). Sex steroid receptors encoded by the oestrogen (ESR1, ESR2), progesterone (PR) and androgen (AR) receptor genes, which are members of the superfamily of ligand activated transcription factors are widely expressed within these tissues. These receptors play critical role(s) in regulation of cell proliferation, ovulation, endometrial receptivity, myometrial cell function and inflammatory cell infiltration. Our understanding of their importance has been informed by studies on human tissues and cells, which have employed immunohistochemistry as well as a wide range of molecular and genetic methods to identify which processes are dependent steroid ligand activation. The development of mice with targeted deletions of each of these receptors has provided complementary data that has extended our appreciation of cell-cell interactions in the fine tuning of reproductive tissue function. This large body of work has formed the basis of new and improved therapeutics to treat conditions such as infertility.
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Affiliation(s)
- Kevin K W Kuan
- Centre for Inflammation Research, The University of Edinburgh, Edinburgh, UK
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3
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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: 24] [Impact Index Per Article: 6.0] [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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Galliou JM, Kiser JN, Oliver KF, Seabury CM, Moraes JGN, Burns GW, Spencer TE, Dalton J, Neibergs HL. Identification of Loci and Pathways Associated with Heifer Conception Rate in U.S. Holsteins. Genes (Basel) 2020; 11:genes11070767. [PMID: 32650431 PMCID: PMC7397161 DOI: 10.3390/genes11070767] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 06/27/2020] [Accepted: 07/06/2020] [Indexed: 12/15/2022] Open
Abstract
Heifer conception rate (HCR) is defined as the percentage of inseminated heifers that become pregnant at each service. The genome-wide association analyses in this study focused on identifying the loci associated with Holstein heifer (n = 2013) conception rate at first service (HCR1) and the number of times bred (TBRD) to achieve a pregnancy. There were 348 unique loci associated (p < 5 × 10−8) with HCR1 and 615 unique loci associated (p < 5 × 10−8) with TBRD. The two phenotypes shared 302 loci, and 56 loci were validated in independent cattle populations. There were 52 transcription factor binding sites (TFBS) and 552 positional candidate genes identified in the HCR1- and TBRD-associated loci. The positional candidate genes and the TFBS associated with HCR1 and TBRD were used in the ingenuity pathway analysis (IPA). In the IPA, 11 pathways, 207 master regulators and 11 upstream regulators were associated (p < 1.23 × 10−5) with HCR1 and TBRD. The validated loci associated with both HCR1 and TBRD make good candidates for genomic selection and further investigations to elucidate the mechanisms associated with subfertility and infertility.
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Affiliation(s)
- Justine M. Galliou
- Department of Animal Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA; (J.M.G.); (J.N.K.); (K.F.O.)
| | - Jennifer N. Kiser
- Department of Animal Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA; (J.M.G.); (J.N.K.); (K.F.O.)
| | - Kayleen F. Oliver
- Department of Animal Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA; (J.M.G.); (J.N.K.); (K.F.O.)
| | - Christopher M. Seabury
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843, USA;
| | - Joao G. N. Moraes
- Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA; (J.G.N.M.); (G.W.B.); (T.E.S.)
| | - Gregory W. Burns
- Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA; (J.G.N.M.); (G.W.B.); (T.E.S.)
| | - Thomas E. Spencer
- Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA; (J.G.N.M.); (G.W.B.); (T.E.S.)
| | - Joseph Dalton
- Department of Animal and Veterinary Sciences, University of Idaho, Caldwell, ID 83844, USA;
| | - Holly L. Neibergs
- Department of Animal Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA; (J.M.G.); (J.N.K.); (K.F.O.)
- Correspondence:
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Lengel D, Huh JW, Barson JR, Raghupathi R. Progesterone treatment following traumatic brain injury in the 11-day-old rat attenuates cognitive deficits and neuronal hyperexcitability in adolescence. Exp Neurol 2020; 330:113329. [PMID: 32335121 DOI: 10.1016/j.expneurol.2020.113329] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/13/2020] [Accepted: 04/22/2020] [Indexed: 12/18/2022]
Abstract
Traumatic brain injury (TBI) in children younger than 4 years old results in cognitive and psychosocial deficits in adolescence and adulthood. At 4 weeks following closed head injury on postnatal day 11, male and female rats exhibited impairment in novel object recognition memory (NOR) along with an increase in open arm time in the elevated plus maze (EPM), suggestive of risk-taking behaviors. This was accompanied by an increase in intrinsic excitability and frequency of spontaneous excitatory post-synaptic currents (EPSCs), and a decrease in the frequency of spontaneous inhibitory post-synaptic currents in layer 2/3 neurons within the medial prefrontal cortex (PFC), a region that is implicated in both object recognition and risk-taking behaviors. Treatment with progesterone for the first week after brain injury improved NOR memory at the 4-week time point in both sham and brain-injured rats and additionally attenuated the injury-induced increase in the excitability of neurons and the frequency of spontaneous EPSCs. The effect of progesterone on cellular excitability changes after injury may be related to its ability to decrease the mRNA expression of the β3 subunit of the voltage-gated sodium channel and increase the expression of the neuronal excitatory amino acid transporter 3 in the medial PFC in sham- and brain-injured animals and also increase glutamic acid decarboxylase mRNA expression in sham- but not brain-injured animals. Progesterone treatment did not affect injury-induced changes in the EPM test. These results demonstrate that administration of progesterone immediately after TBI in 11-day-old rats reduces cognitive deficits in adolescence, which may be mediated by progesterone-mediated regulation of excitatory signaling mechanisms within the medial PFC.
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Affiliation(s)
- Dana Lengel
- Program in Neuroscience, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, Philadelphia, PA United States of America
| | - Jimmy W Huh
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Jessica R Barson
- Program in Neuroscience, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, Philadelphia, PA United States of America; Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States of America
| | - Ramesh Raghupathi
- Program in Neuroscience, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, Philadelphia, PA United States of America; Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States of America.
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6
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The Regulation of Uterine Function During Parturition: an Update and Recent Advances. Reprod Sci 2020; 27:3-28. [DOI: 10.1007/s43032-019-00001-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 03/19/2019] [Indexed: 12/13/2022]
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7
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Abstract
In the United States, the generally accepted indication for tocolytic therapy centers on suppression of preterm labor. This may be in the form of preventative therapy with progesterone in women with prior spontaneous preterm birth or as an acute intervention to suppress established uterine contractions associated with cervical change occurring at less than 37 weeks gestation. This article seeks to apply this perspective to tocolytic therapy. Here, we provide a review of current tocolytic options and what the last decade of discovery has revealed about the regulation of myometrial excitability and quiescence. Moving forward, we must incorporate the emerging molecular data that is amassing in order to develop novel and effective tocolytic therapeutic options to prevent preterm labor and spontaneous preterm birth (sPTB).
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Affiliation(s)
| | | | - George Gallos
- Department of Anesthesia, Columbia University Medical Center, New York, NY.
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Shi JH, Jin L, Leng JH, Lang JH. Expression of Potassium Channels in Uterine Smooth Muscle Cells from Patients with Adenomyosis. Chin Med J (Engl) 2017; 129:200-5. [PMID: 26830992 PMCID: PMC4799548 DOI: 10.4103/0366-6999.173491] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Adenomyosis (AM) has impaired contraction. This study aimed to explore the expression of potassium channels related to contraction in myometrial smooth muscle cells (MSMCs) of AM. METHODS Uterine tissue samples from 22 patients (cases) with histologically confirmed AM and 12 (controls) with cervical intraepithelial neoplasia were collected for both immunohistochemistry and real-time polymerase chain reaction to detect the expression of large conductance calcium- and voltage-sensitive K + channel (BKCa)-α/β subunits, voltage-gated potassium channel (Kv) 4.2, and Kv4.3. Student's t-test was used to compare the expression. RESULTS The BKCa-α/β subunits, Kv4.2, and Kv4.3 were located in smooth muscle cells, glandular epithelium, and stromal cells. However, BKCa-β subunit expression in endometrial glands of the controls was weak, and Kv4.3 was almost undetectable in the controls. The expression of BKCa-α messenger RNA (mRNA) (0.62 ± 0.19-fold decrease, P < 0.05) and Kv4.3 mRNA (0.67 ± 0.20-fold decrease, P < 0.05) decreased significantly in the MSMCs of the control group compared with the AM group. However, there were no significant differences in BKCa-β subunit mRNA or Kv4.2 mRNA. CONCLUSIONS The BKCa-α mRNA and the Kv4.3 mRNA are expressed significantly higher in AM than those in the control group, that might cause the abnormal uterus smooth muscle contractility, change the microcirculation of uterus to accumulate the inflammatory factors, impair the endometrium further, and aggravate the pain.
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Affiliation(s)
| | - Li Jin
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China
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Kow LM, Pfaff DW. Rapid estrogen actions on ion channels: A survey in search for mechanisms. Steroids 2016; 111:46-53. [PMID: 26939826 PMCID: PMC4929851 DOI: 10.1016/j.steroids.2016.02.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 02/22/2016] [Accepted: 02/25/2016] [Indexed: 12/31/2022]
Abstract
A survey of nearly two hundred reports shows that rapid estrogenic actions can be detected across a range of kinds of estrogens, a range of doses, on a wide range of tissue, cell and ion channel types. Striking is the fact that preparations of estrogenic agents that do not permeate the cell membrane almost always mimic the actions of the estrogenic agents that do permeate the membrane. All kinds of estrogens, ranging from natural ones, through receptor modulators, endocrine disruptors, phytoestrogens, agonists, and antagonists to novel G-1 and STX, have been reported to be effective. For actions on specific types of ion channels, the possibility of opposing actions, in different cases, is the rule, not the exception. With this variety there is no single, specific action mechanism for estrogens per se, although in some cases estrogens can act directly or via some signaling pathways to affect ion channels. We infer that estrogens can bind a large number of substrates/receptors at the membrane surface. As against the variety of subsequent routes of action, this initial step of the estrogen's binding action is the key.
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Affiliation(s)
- Lee-Ming Kow
- The Rockefeller University, New York, NY 10065, USA.
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10
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Novakovi R, Radunovi N, Markovi -Lipkovski J, irovi S, Beleslin- oki B, Ili B, Ivkovi B, Heinle H, ivanovi V, Gojkovi -Bukarica L. Effects of the polyphenol resveratrol on contractility of human term pregnant myometrium. Mol Hum Reprod 2015; 21:545-51. [DOI: 10.1093/molehr/gav011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 03/02/2015] [Indexed: 12/27/2022] Open
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11
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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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Acute blockage of voltage-gated K⁺ currents by 17β-estradiol in mouse neuroblastoma N2A cells. Neuroreport 2014; 25:574-9. [PMID: 24784585 DOI: 10.1097/wnr.0000000000000137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this study, whole-cell recording was carried out to explore the effects of 17β-estradiol on voltage-gated K⁺ (Kv) currents in N2A cells. The acute exposure to 17β-estradiol, in a concentration-dependent manner, significantly inhibited the peak and steady-state currents through Kv channels, showing IC50 values of 3.6 and 3.8 μM, respectively. The reduction in both the amplitude and the decay rate of Kv currents, with an increase in depolarization, suggested that it was a voltage-dependent block. The activation and inactivation experiments were conducted to determine the exact causes of the inhibitory effects. The half-maximum activation potential (V₁/₂) was +8.1 mV in control and remained stable after exposure to 10 μM 17β-estradiol. For steady-state inactivation, the half-maximum inactivation potential (V₁/₂) was -45.0 mV and shifted right to -39.7 mV without a statistical difference, and the time constants of recovery from inactivation were not altered by 17β-estradiol, suggesting that the depression was not correlated with the inactivation gate.
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13
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Heyman NS, Cowles CL, Barnett SD, Wu YY, Cullison C, Singer CA, Leblanc N, Buxton ILO. TREK-1 currents in smooth muscle cells from pregnant human myometrium. Am J Physiol Cell Physiol 2013; 305:C632-42. [PMID: 23804201 PMCID: PMC3761174 DOI: 10.1152/ajpcell.00324.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 06/24/2013] [Indexed: 01/05/2023]
Abstract
The mechanisms governing maintenance of quiescence during pregnancy remain largely unknown. The current study characterizes a stretch-activated, tetraethylammonium-insensitive K(+) current in smooth muscle cells isolated from pregnant human myometrium. This study hypothesizes that these K(+) currents can be attributed to TREK-1 and that upregulation of this channel during pregnancy assists with the maintenance of a negative cell membrane potential, conceivably contributing to uterine quiescence until full term. The results of this study demonstrate that, in pregnant human myometrial cells, outward currents at 80 mV increased from 4.8 ± 1.5 to 19.4 ± 7.5 pA/pF and from 3.0 ± 0.8 to 11.8 ± 2.7 pA/pF with application of arachidonic acid (AA) and NaHCO3, respectively, causing intracellular acidification. Similarly, outward currents were inhibited following application of 10 μM fluphenazine by 51.2 ± 9.8% after activation by AA and by 73.9 ± 4.2% after activation by NaHCO3. In human embryonic kidney (HEK-293) cells stably expressing TREK-1, outward currents at 80 mV increased from 91.0 ± 23.8 to 247.5 ± 73.3 pA/pF and from 34.8 ± 8.9 to 218.6 ± 45.0 pA/pF with application of AA and NaHCO3, respectively. Correspondingly, outward currents were inhibited 89.5 ± 2.3% by 10 μM fluphenazine following activation by AA and by 91.6 ± 3.4% following activation by NaHCO3. Moreover, currents in human myometrial cells were activated by stretch and were reduced by transfection with small interfering RNA or extracellular acidification. Understanding gestational regulation of expression and gating of TREK-1 channels could be important in determining appropriate maintenance of uterine quiescence during pregnancy.
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Affiliation(s)
- Nathanael S Heyman
- Department of Pharmacology, Center for Molecular Medicine, University of Nevada School of Medicine, Reno, Nevada
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14
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Hong SH, Sung R, Kim YC, Suzuki H, Choi W, Park YJ, Ji IW, Kim CH, Myung SC, Lee MY, Kang TM, You RY, Lee KJ, Lim SW, Yun HY, Song YJ, Xu WX, Kim HS, Lee SJ. Mechanism of Relaxation Via TASK-2 Channels in Uterine Circular Muscle of Mouse. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2013; 17:359-65. [PMID: 23946696 PMCID: PMC3741493 DOI: 10.4196/kjpp.2013.17.4.359] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 06/24/2013] [Accepted: 06/27/2013] [Indexed: 11/19/2022]
Abstract
Plasma pH can be altered during pregnancy and at labor. Membrane excitability of smooth muscle including uterine muscle is suppressed by the activation of K+ channels. Because contractility of uterine muscle is regulated by extracellular pH and humoral factors, K+ conductance could be connected to factors regulating uterine contractility during pregnancy. Here, we showed that TASK-2 inhibitors such as quinidine, lidocaine, and extracellular acidosis produced contraction in uterine circular muscle of mouse. Furthermore, contractility was significantly increased in pregnant uterine circular muscle than that of non-pregnant muscle. These patterns were not changed even in the presence of tetraetylammonium (TEA) and 4-aminopyridine (4-AP). Finally, TASK-2 inhibitors induced strong myometrial contraction even in the presence of L-methionine, a known inhibitor of stretchactivated channels in myometrium. When compared to non-pregnant myometrium, pregnant myometrium showed increased immunohistochemical expression of TASK-2. Therefore, TASK-2, seems to play a key role during regulation of myometrial contractility in the pregnancy and provides new insight into preventing preterm delivery.
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Affiliation(s)
- Seung Hwa Hong
- Department of Obstetrics and Gynecology, Chungbuk National University College of Medicine, Cheongju 361-763, Korea
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15
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Welsh T, Johnson M, Yi L, Tan H, Rahman R, Merlino A, Zakar T, Mesiano S. Estrogen receptor (ER) expression and function in the pregnant human myometrium: estradiol via ERα activates ERK1/2 signaling in term myometrium. J Endocrinol 2012; 212:227-38. [PMID: 22068927 DOI: 10.1530/joe-11-0358] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Estrogens are thought to promote labor by increasing the expression of pro-contraction genes in myometrial cells. The specific estrogen receptors ((ERs: ERα and ERβ (also known as ESR1 and ESR2)) and G protein-coupled receptor 30 (GPR30; also known as G protein-coupled estrogen receptor 1)) and signaling pathways that mediate these actions are not clearly understood. In this study, we identified the ERs expressed in the pregnant human myometrium and determined a key extranuclear signaling pathway through which estradiol (E(2)) modulates expression of the gene encoding the oxytocin receptor (OXTR), a major pro-contraction protein. Using quantitative RT-PCR, we found that ERα and GPR30 mRNAs were expressed in the human pregnant myometrium while ERβ mRNA was virtually undetectable. While mRNA encoding ERα was the predominant ER transcript in the pregnant myometrium, ERα protein was largely undetectable in myometrial tissue by immunoblotting. Pharmacological inhibition of 26S proteasome activity increased ERα protein abundance to detectable levels in term myometrial explants, however, indicating rapid turnover of ERα protein by proteasomal processing in the pregnant myometrium. E(2) stimulated rapid extranuclear signaling in myometrial explants, as evidenced by increased extracellularly regulated kinase (ERK1/2) phosphorylation within 10 min. This effect was inhibited by pre-treatment with an ER antagonist, ICI 182 780, indicating the involvement of ERα. Inhibition of ERK signaling abrogated the ability of E(2) to stimulate OXTR gene expression in myometrial explants. We conclude that estrogenic actions in the human myometrium during pregnancy, including the stimulation of contraction-associated gene expression, can be mediated by extranuclear signaling through ERα via activation of the ERK/mitogen-activated protein kinase pathway.
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Affiliation(s)
- Toni Welsh
- Department of Reproductive Biology, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, Ohio 44106, USA
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16
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Soloff MS, Jeng YJ, Izban MG, Sinha M, Luxon BA, Stamnes SJ, England SK. Effects of progesterone treatment on expression of genes involved in uterine quiescence. Reprod Sci 2011; 18:781-97. [PMID: 21795739 PMCID: PMC4051400 DOI: 10.1177/1933719111398150] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
An important action of progesterone during pregnancy is to maintain the uterus in a quiescent state and thereby prevent preterm labor. The causes of preterm labor are not well understood, so progesterone action on the myometrium can provide clues about the processes that keep the uterus from contracting prematurely. Accordingly, we have carried out Affymetrix GeneChip analysis of progesterone effects on gene expression in immortalized human myometrial cells cultured from a patient near the end of pregnancy. Progesterone appears to inhibit uterine excitability by a number of mechanisms, including increased expression of calcium and voltage-operated K(+) channels, which dampens the electrical activity of the myometrial cell, downregulation of agents, and receptors involved in myometrial contraction, reduction in cell signal components that lead to increased intracellular Ca(2+) concentrations in response to contractile stimuli, and downregulation of proteins involved in the cross-linking of actin and myosin filaments to produce uterine contractions.
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Affiliation(s)
- Melvyn S. Soloff
- Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, TX, USA
| | - Yow-Jiun Jeng
- Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, TX, USA
| | - Michael G. Izban
- Department of Obstetrics and Gynecology, Meharry Medical College, Nashville, TN, USA
| | - Mala Sinha
- Department of Biochemistry and Molecular Biology, and the Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, TX, USA
| | - Bruce A. Luxon
- Department of Biochemistry and Molecular Biology, and the Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, TX, USA
| | - Susan J. Stamnes
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - Sarah K. England
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, 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: 53] [Impact Index Per Article: 4.1] [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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18
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Monaghan K, Baker SA, Dwyer L, Hatton WC, Sik Park K, Sanders KM, Koh SD. The stretch-dependent potassium channel TREK-1 and its function in murine myometrium. J Physiol 2011; 589:1221-33. [PMID: 21224218 DOI: 10.1113/jphysiol.2010.203869] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Smooth muscle of the uterus stays remarkably quiescent during normal pregnancy to allow sufficient time for development of the fetus. At present the mechanisms leading to uterine quiescence during pregnancy and how the suppression of activity is relieved at term are poorly understood. Myometrial excitability is governed by ion channels, and a major hypothesis regarding the regulation of contractility during pregnancy has been that expression of certain channels is regulated by hormonal influences. We have explored the expression and function of stretch-dependent K+ (SDK) channels, which are likely to be due to TREK channels, in murine myometrial tissues and myocytes using PCR, Western blots, patch clamp, intracellular microelectrode and isometric force measurements. TREK-1 is more highly expressed than TREK-2 in myometrium, and there was no detectable expression of TRAAK. Expression of TREK-1 transcripts and protein was regulated during pregnancy and delivery. SDK channels were activated in response to negative pressure applied to patches. SDK channels were insensitive to a broad-spectrum of K+ channel blockers, including tetraethylammonium and 4-aminopyridine, and insensitive to intracellular Ca2+. SDK channels were activated by stretch and arachidonic acid and inhibited by reagents that block TREK-1 channels, l-methionine and/or methioninol. Our data suggest that uterine excitability and contractility during pregnancy is regulated by the expression of SDK/TREK-1 channels. Up-regulation of these channels stabilizes membrane potential and controls contraction during pregnancy and down-regulation of these channels induces the onset of delivery.
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Affiliation(s)
- Kevin Monaghan
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
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19
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Hill M, Pařízek A, Kancheva R, Jirásek JE. Reduced progesterone metabolites in human late pregnancy. Physiol Res 2010; 60:225-41. [PMID: 21114373 DOI: 10.33549/physiolres.932077] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In this review, we focused on the intersection between steroid metabolomics, obstetrics and steroid neurophysiology to give a comprehensive insight into the role of sex hormones and neuroactive steroids (NAS) in the mechanism controlling pregnancy sustaining. The data in the literature including our studies show that there is a complex mechanism providing synthesis of either pregnancy sustaining or parturition provoking steroids. This mechanism includes the boosting placental synthesis of CRH with approaching parturition inducing the excessive synthesis of 3beta-hydroxy-5-ene steroid sulfates serving primarily as precursors for placental synthesis of progestogens, estrogens and NAS. The distribution and changing activities of placental oxidoreductases are responsible for the activation or inactivation of the aforementioned steroids, which is compartment-specific (maternal and fetal compartments) and dependent on gestational age, with a tendency to shift the production from the pregnancy-sustaining steroids to the parturition provoking ones with an increasing gestational age. The fetal and maternal livers catabolize part of the bioactive steroids and also convert some precursors to bioactive steroids. Besides the progesterone, a variety of its 5alpha/beta-reduced metabolites may significantly influence the maintenance of human pregnancy, provide protection against excitotoxicity following acute hypoxic stress, and might also affect the pain perception in mother and fetus.
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Affiliation(s)
- M Hill
- Department of Obstetrics and Gynecology of the First Faculty of Medicine and General Teaching Hospital, Prague, Czech Republic.
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20
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Hill M, Pařízek A, Cibula D, Kancheva R, Jirásek JE, Jirkovská M, Velíková M, Kubátová J, Klímková M, Pašková A, Zižka Z, Kancheva L, Kazihnitková H, Zamrazilová L, Stárka L. Steroid metabolome in fetal and maternal body fluids in human late pregnancy. J Steroid Biochem Mol Biol 2010; 122:114-32. [PMID: 20580824 DOI: 10.1016/j.jsbmb.2010.05.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 05/13/2010] [Accepted: 05/14/2010] [Indexed: 12/27/2022]
Abstract
Despite the extensive research during the last six decades the fundamental questions concerning the role of steroids in the initiation of human parturition and origin and function of some steroids in pregnancy were not definitely answered. Based on steroid metabolomic data found in the literature and our so far unpublished results, we attempted to bring new insights concerning the role of steroids in the sustaining and termination of human pregnancy, and predictive value of these substances for estimation of term. We also aimed to explain enigmas concerning the biosynthesis of progesterone and its bioactive catabolites considering the conjunctions between placental production of CRH, synthesis of bioactive steroids produced by fetal adrenal, localization of placental oxidoreductases and sustaining of human pregnancy. Evaluation of data available in the literature, including our recent findings as well as our new unpublished data indicates increasing progesterone synthesis and its concurrently increasing catabolism with approaching parturition, confirms declining production of pregnancy sustaining 5β-pregnane steroids providing uterine quiescence in late pregnancy, increased sulfation of further neuroinhibiting and pregnancy sustaining steroids. In contrast to the established concept considering LDL cholesterol as the primary substrate for progesterone synthesis in pregnancy, our data demonstrates the functioning of alternative mechanism for progesterone synthesis, which is based on the utilization of fetal pregnenolone sulfate for progesterone production in placenta. Close relationships were found between localization of placental oxidoreductases and consistently higher levels of sex hormones, neuroactive steroids and their metabolites in the oxidized form in the fetus and in the reduced form in the maternal compartment.
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Affiliation(s)
- Martin Hill
- Institute of Endocrinology, Národní třída 8, Prague CZ 116 94, Czech Republic.
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21
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Weiner CP, Mason CW, Dong Y, Buhimschi IA, Swaan PW, Buhimschi CS. Human effector/initiator gene sets that regulate myometrial contractility during term and preterm labor. Am J Obstet Gynecol 2010; 202:474.e1-20. [PMID: 20452493 DOI: 10.1016/j.ajog.2010.02.034] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Revised: 01/10/2010] [Accepted: 02/10/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVE Distinct processes govern transition from quiescence to activation during term (TL) and preterm labor (PTL). We sought gene sets that are responsible for TL and PTL, along with the effector genes that are necessary for labor independent of gestation and underlying trigger. STUDY DESIGN Expression was analyzed in term and preterm with or without labor (n=6 subjects/group). Gene sets were generated with logic operations. RESULTS Thirty-four genes were expressed similarly in PTL/TL but were absent from nonlabor samples (effector set); 49 genes were specific to PTL (preterm initiator set), and 174 genes were specific to TL (term initiator set). The gene ontogeny processes that comprise term initiator and effector sets were diverse, although inflammation was represented in 4 of the top 10; inflammation dominated the preterm initiator set. CONCLUSION TL and PTL differ dramatically in initiator profiles. Although inflammation is part of the term initiator and the effector sets, it is an overwhelming part of PTL that is associated with intraamniotic inflammation.
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Mock embryo transfer does not affect uterine contractility. Fertil Steril 2010; 93:1343-6. [DOI: 10.1016/j.fertnstert.2008.10.054] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2008] [Revised: 10/24/2008] [Accepted: 10/29/2008] [Indexed: 11/24/2022]
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23
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Hill M, Pařízek A, Velíková M, Kubátová J, Kancheva R, Dušková M, Šimůnková K, Klímková M, Pašková A, Žižka Z, Jirásek JE, Jirkovská M, Stárka L. The distribution of placental oxidoreductase isoforms provides different milieus of steroids influencing pregnancy in the maternal and fetal compartment. Horm Mol Biol Clin Investig 2010; 4:581-600. [DOI: 10.1515/hmbci.2010.077] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 11/24/2010] [Indexed: 12/27/2022]
Abstract
AbstractUsing information based on the steroid metabolome in maternal and fetal body fluids, we attempted to ascertain whether there is a common mechanism, which is based on the placental distribution of various isoforms of 17β-hydroxysteroid dehydrogenases and aldo-keto reductases. This system simultaneously provides a higher proportion of active progestogens in fetal circulation and a higher proportion of active estrogens and GABAergic steroids in the maternal compartment. The data obtained using gas chromatography-mass spectrometry completely support the aforementioned hypothesis. We confirmed a common trend to higher ratios of steroids with hydroxy-groups in the 3α-, 17β-, and 20α-positions to the corresponding 3-oxo-, 17-oxo-, and 20-oxo-metabolites, respectively, in the maternal blood when compared with the fetal circulation, and the same tendency was obvious in the 3α-hydroxy/3β-hydroxy steroid ratios. A decreasing trend was observed in the ratios of active estrogens and neuro-inhibitory steroids to their inactive counterparts in fetal and maternal body fluids. This was probably associated with a limited capacity of placental oxidoreductases in the converting of estrone to estradiol during the transplacental passage. Although we observed a decreasing trend in pregnancy-sustaining steroids with increasing gestational age, we recorded rising levels of estradiol and particularly of estriol, regardless of the limited capacity of placental oxidoreductases. Besides the estradiol, which is generally known as an active estrogen, estriol may be of importance for the termination of pregnancy with respect to its excessive concentrations near term which allows its binding to estrogen receptors.
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24
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Anderson L, Martin W, Higgins C, Nelson SM, Norman JE. The Effect of Progesterone on Myometrial Contractility, Potassium Channels, and Tocolytic Efficacy. Reprod Sci 2009; 16:1052-61. [DOI: 10.1177/1933719109340926] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Laurie Anderson
- Reproductive and Maternal Medicine, Institute of Biomedical and Life Sciences University of Glasgow, Scotland, UK,
| | - William Martin
- Integrative and Systems Biology, Institute of Biomedical and Life Sciences University of Glasgow, Scotland, UK
| | - Claire Higgins
- Reproductive and Maternal Medicine, Institute of Biomedical and Life Sciences University of Glasgow, Scotland, UK
| | - Scott M. Nelson
- Reproductive and Maternal Medicine, Institute of Biomedical and Life Sciences University of Glasgow, Scotland, UK
| | - Jane E. Norman
- Centre for Reproductive Biology, University of Edinburgh, Scotland, UK
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25
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McCallum LA, Greenwood IA, Tribe RM. Expression and function of Kv7 channels in murine myometrium throughout oestrous cycle. Pflugers Arch 2008; 457:1111-20. [DOI: 10.1007/s00424-008-0567-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Accepted: 07/29/2008] [Indexed: 12/22/2022]
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26
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Celik O, Hascalik S, Tagluk ME, Elter K, Parlakpinar H, Acet A. Assessment of myoelectrical signal parameters in estrogen, progesterone, and human chorionic gonadotropin administered in nonpregnant rat myometrium after ovariectomy. Fertil Steril 2008; 89:188-98. [PMID: 17509589 DOI: 10.1016/j.fertnstert.2007.02.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 02/12/2007] [Accepted: 02/12/2007] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate the correlation of myoelectrical signals with spontaneous contractile events and physiological states in the nonisolated uterine horn of rats. DESIGN In vivo uterine myoelectrical activity recording study. SETTING Animal and pharmacology laboratory at Inonu University. ANIMAL(S) Thirty-six female Wistar albino rats. INTERVENTION(S) Six animals were not castrated and served as a sham-operated control group; the other 30 were ovariectomized (OVX) and put into groups: unbiased OVX subjects, estrogen (E)-biased OVX subjects, P-biased OVX subjects, E-plus-P-biased OVX subjects, and hCG-biased OVX subjects. An MP100 A-CE was used for data acquisition, and a personal computer was used for processing. MAIN OUTCOME MEASURE(S) Besides the temporal, spectral, and joint time-frequency (spectrotemporal) analysis, some quantitative measures such as standard deviation and mark to space power ratios of myoelectrical signals were measured. RESULT(S) Progesterone, E, and hCG administration down-regulated the power and contraction frequency of the uterine electrical signal. The spectral concentrations that occurred around the 0.9, 0.35, and 0.7 Hz frequency ranges may be distinguishing characteristics for P, E, and hCG, respectively. CONCLUSION(S) Based on the obtained results, uterine contractions change with ovariectomy and administration of hormones. Progesterone, E, and hCG particularly prolong the quiescent periods of the uterus by reducing the frequency of uterine contractions as well as the power of the myoelectrical activity. Individual or combined use of P, E, or hCG might favor quiescence of the uterine muscle and the maintenance of pregnancy.
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Affiliation(s)
- Onder Celik
- Department of Obstetrics and Gynecology, Inonu University Medical Faculty, Malatya, Turkey.
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27
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Doret M, Pasquier JC, Gharib C, Gaucherand P. [Uterine electromyogram: principle and interest in the diagnosis of preterm labour]. ACTA ACUST UNITED AC 2007; 37:24-32. [PMID: 18036747 DOI: 10.1016/j.jgyn.2007.08.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Revised: 07/10/2007] [Accepted: 08/27/2007] [Indexed: 10/22/2022]
Abstract
Preterm labour diagnosis rely on clinical arguments exhibiting low positive predictive values. Discrimination between uterine contractions leading to preterm delivery and physiologic uterine activity increase throughout pregnancy and remains difficult. Uterine electrical activity can be recorded non-invasively from the abdominal wall and could help in the diagnosis of preterm labour. Electrical signal characteristics are reflecting myometrial cells electrical properties which are varying throughout pregnancy and labour. During pregnancy, uterine electrical activity is very low. During term and preterm labour, uterine electrical activity increases as well as mechanical activity. Bursts become regular with high amplitude. Spectral analysis demonstrates an increase in the frequency content, as represented by the shift of the burst power density spectrum peak frequency from low to high frequencies. Consequently, the electromyogram signal reflects myometrial excitability and allows differentiating powerful uterine contractions leading to delivery from uterine physiologic activity. Moreover, electromyogram signal modifications occur before any increase in mechanical activity in the pregnant rats, allowing identification of preterm labour earlier than uterine mechanical activity measured by intrauterine pressure. Two studies performed in women present with preterm contractions are supporting the potential interest of the uterine electromyogram recording to help in the diagnosis of preterm labour; but further investigations are necessary.
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Affiliation(s)
- M Doret
- Département de gynécologie-obstétrique, hospices civils de Lyon, hôpital Edouard-Herriot, place d'Arsonval, Lyon cedex 03, France.
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28
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McAnelly ML, Zakon HH. Androgen modulates the kinetics of the delayed rectifying K+ current in the electric organ of a weakly electric fish. Dev Neurobiol 2007; 67:1589-97. [PMID: 17562532 DOI: 10.1002/dneu.20530] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Weakly electric fish such as Sternopygus macrurus utilize a unique signal production system, the electric organ (EO), to navigate within their environment and to communicate with conspecifics. The electric organ discharge (EOD) generated by the Sternopygus electric organ is quasi-sinusoidal and sexually dimorphic; sexually mature males produce long duration EOD pulses at low frequencies, whereas mature females produce short duration EOD pulses at high frequencies. EOD frequency is set by a medullary pacemaker nucleus, while EOD pulse duration is determined by the kinetics of Na+ and K+ currents in the electric organ. The inactivation of the Na+ current and the activation of the delayed rectifying K+ current of the electric organ covary with EOD frequency such that the kinetics of both currents are faster in fish with high (female) EOD frequency than those with low (male) EOD frequencies. Dihydrotestosterone (DHT) implants masculinize the EOD centrally by decreasing frequency at the pacemaker nucleus (PMN). DHT also acts at the electric organ, broadening the EO pulse, which is at least partly due to a slowing of the inactivation kinetics of the Na+ current. Here, we show that chronic DHT treatment also slows the activation and deactivation kinetics of the electric organ's delayed rectifying K+ current. Thus, androgens coregulate the time-varying kinetics of two distinct ion currents in the EO to shape a sexually dimorphic communication signal.
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Affiliation(s)
- M Lynne McAnelly
- Section of Neurobiology, The University of Texas, Austin, Texas 78712, USA.
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29
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Smith RC, McClure MC, Smith MA, Abel PW, Bradley ME. The role of voltage-gated potassium channels in the regulation of mouse uterine contractility. Reprod Biol Endocrinol 2007; 5:41. [PMID: 17980032 PMCID: PMC2186335 DOI: 10.1186/1477-7827-5-41] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Accepted: 11/02/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Uterine smooth muscle cells exhibit ionic currents that appear to be important in the control of uterine contractility, but how these currents might produce the changes in contractile activity seen in pregnant myometrium has not been established. There are conflicting reports concerning the role of voltage-gated potassium (Kv) channels and large-conductance, calcium-activated potassium (BK) channels in the regulation of uterine contractility. In this study we provide molecular and functional evidence for a role for Kv channels in the regulation of spontaneous contractile activity in mouse myometrium, and also demonstrate a change in Kv channel regulation of contractility in pregnant mouse myometrium. METHODS Functional assays which evaluated the effects of channel blockers and various contractile agonists were accomplished by quantifying contractility of isolated uterine smooth muscle obtained from nonpregnant mice as well as mice at various stages of pregnancy. Expression of Kv channel proteins in isolated uterine smooth muscle was evaluated by Western blots. RESULTS The Kv channel blocker 4-aminopyridine (4-AP) caused contractions in nonpregnant mouse myometrium (EC50 = 54 micromolar, maximal effect at 300 micromolar) but this effect disappeared in pregnant mice; similarly, the Kv4.2/Kv4.3 blocker phrixotoxin-2 caused contractions in nonpregnant, but not pregnant, myometrium. Contractile responses to 4-AP were not dependent upon nerves, as neither tetrodotoxin nor storage of tissues at room temperature significantly altered these responses, nor were responses dependent upon the presence of the endometrium. Spontaneous contractions and contractions in response to 4-AP did not appear to be mediated by BK, as the BK channel-selective blockers iberiotoxin, verruculogen, or tetraethylammonium failed to affect either spontaneous contractions or 4-AP-elicited responses. A number of different Kv channel alpha subunit proteins were found in isolated myometrium from both nonpregnant and term-pregnant mice, and one of these proteins - Kv4.3 - was found to disappear in term-pregnant tissues. CONCLUSION These findings suggest a role for Kv channels in the regulation of uterine contractility, and that changes in the expression and/or function of specific Kv channels may account for the functional changes seen in pregnant myometrium.
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Affiliation(s)
- Ryan C Smith
- Department of Pharmacology, Creighton University Medical Center, Omaha, USA, NE 68178
| | - Marisa C McClure
- Department of Pharmacology, Creighton University Medical Center, Omaha, USA, NE 68178
| | - Margaret A Smith
- Department of Pharmacology, Creighton University Medical Center, Omaha, USA, NE 68178
| | - Peter W Abel
- Department of Pharmacology, Creighton University Medical Center, Omaha, USA, NE 68178
| | - Michael E Bradley
- Department of Pharmacology, Creighton University Medical Center, Omaha, USA, NE 68178
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30
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Brainard AM, Korovkina VP, England SK. Potassium channels and uterine function. Semin Cell Dev Biol 2007; 18:332-9. [PMID: 17596977 PMCID: PMC2012947 DOI: 10.1016/j.semcdb.2007.05.008] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Accepted: 05/03/2007] [Indexed: 01/14/2023]
Abstract
Ion channels are effector proteins that mediate uterine excitability throughout gestation. This review will focus primarily on the role of potassium channels in regulating myometrial tone in pregnancy and labor contractions. During gestation, potassium channels maintain the uterus in a state of quiescence by contributing to the resting membrane potential and counteracting contractile stimuli. This review summarizes the current knowledge about the significance of the potassium channels in maintaining a normal gestational period and initiating labor contractions at term.
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Affiliation(s)
- Adam M Brainard
- University of Iowa Carver College of Medicine, Department of Molecular Physiology and Biophysics, Iowa City, IA 52242, United States
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31
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Sawada K, Morishige KI, Hashimoto K, Tasaka K, Kurachi H, Murata Y, Kurachi Y. Gestational change of K+ channel opener effect is correlated with the expression of uterine KATP channel subunits. Eur J Obstet Gynecol Reprod Biol 2005; 122:49-56. [PMID: 16154039 DOI: 10.1016/j.ejogrb.2004.11.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Revised: 11/10/2004] [Accepted: 11/25/2004] [Indexed: 11/20/2022]
Abstract
OBJECTIVE We analyzed the gestational changes of pharmacological activity and molecular levels of KATP channels in rat myometrium. STUDY DESIGN Using rat myometrium, the effects of K+ channel openers (KCOs) were examined in an isometric tension study of oxytocin-induced contraction. We also examined the effects of KCOs on the intracellular Ca2+ levels of cultured myometrial cells. The expression of myometrial KATP channels was assessed by RT-PCR and Northern blot analysis. RESULTS The effect of KCOs were altered during pregnancy, with a significant increase of their potency at day 18 of pregnancy followed by a decline towards the non-pregnant level at the day of delivery. KCOs suppressed the Ca2+ influx across the cell membrane. The mRNAs encoding each component of myometrial KATP channels, Kir6.1 and SUR2B, exhibited gestational stage-dependent alterations similar to those of the effects of KCOs. CONCLUSION These findings suggest that KCOs inhibit uterine myometrial contraction more effectively during pregnancy than in the non-pregnant state due to gestation-enhanced expression of KATP channels, implying that KCOs might be useful for preventing premature delivery.
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Affiliation(s)
- Kenjiro Sawada
- Department of Obstetrics and Gynecology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
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32
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Perusquía M, Navarrete E, Jasso-Kamel J, Montaño LM. Androgens Induce Relaxation of Contractile Activity in Pregnant Human Myometrium at Term: A Nongenomic Action on L-Type Calcium Channels1. Biol Reprod 2005; 73:214-21. [PMID: 15758151 DOI: 10.1095/biolreprod.104.036954] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
It has long been accepted that progesterone regulates uterine contractile activity. However, little is known about the role of androgens in female physiology, and their importance and biological function on myometrial contractility so far have received limited attention. In this work, we examined the direct effect of androgens on the contractile activity of the isolated human myometrium. Myometrial biopsies were obtained, with consent, from pregnant women undergoing elective cesarean section at term. Each androgen tested (dehydroepiandrosterone, testosterone, 5alpha- and 5beta-dihydrotestosterone, androsterone, or androstanediol) caused a concentration-dependent inhibition of spontaneous contractile activity; a relaxing effect of these androgens was also observed on the contractions induced by high potassium (KCl) solution. Interestingly, nonpregnant myometrium was also sensitive to androgen-induced relaxation. 5beta-Dihydrotestosterone (5beta-DHT) was dramatically more potent than the other androgens in inducing myometrial relaxation in all preparations. Relaxation response to androgens had very rapid time courses and was affected by neither the specific antiandrogen (flutamide) nor inhibitors of protein synthesis (cycloheximide) and transcription (actinomycin D), implying that androgens act through a nongenomic mechanism. Importantly, 5beta-DHT significantly reduced the increase in intracellular calcium concentration associated with exposure to KCl in human myometrial smooth-muscle cells loaded with Fura-2-AM. The blockade of l-type calcium channels seems to be involved in the nongenomic relaxing action of androgens. These observations demonstrate that androgens may play a crucial role in maintaining pregnancy.
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Affiliation(s)
- Mercedes Perusquía
- Departamento de Biología Celular y Fisiología, Universidad Nacional Autónoma de México, México.
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Sculptoreanu A, de Groat WC, Buffington CAT, Birder LA. Abnormal excitability in capsaicin-responsive DRG neurons from cats with feline interstitial cystitis. Exp Neurol 2005; 193:437-43. [PMID: 15869946 DOI: 10.1016/j.expneurol.2005.01.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Revised: 01/12/2005] [Accepted: 01/19/2005] [Indexed: 11/24/2022]
Abstract
Interstitial cystitis (IC) is a painful disorder which affects urinary bladder function in cats and humans. We used patch clamp techniques to measure firing properties and K+ currents of dorsal root ganglion (DRG) neurons (L4-S3) from normal cats and cats with feline interstitial cystitis (FIC) to examine the possibility that the properties of primary afferent neurons are changed in cats with FIC. We found that capsaicin (CAPS)-responsive neurons from FIC cats were increased in size, had increased firing in response to depolarizing current pulses and expressed more rapidly inactivating K+ currents. CAPS-sensitive neurons from FIC cats were 28% larger than those from normal cats but were otherwise similar with respect to membrane potential and action potential (AP) threshold. CAPS-responsive neurons from normal cats fired 1.5 APs in response to a 600 ms depolarizing current pulse, 60-200 pA in intensity. The number of APs was increased 4.5 fold in FIC neurons. Neurons from FIC cats also exhibited after hyperpolarization potentials which were on the average 2x slower than those in normal cat neurons. In addition, there was a lack of K+ currents in the critical voltage range of action potential generation (between -50 to -30 mV). These changes were not detected in CAPS-unresponsive neurons from normal and FIC cats. Our data suggest that FIC afferent neurons exhibit abnormal firing which may be due to changes in the behavior of K+ currents and show that these changes are restricted to a subpopulation of CAPS-responsive neurons.
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Affiliation(s)
- Adrian Sculptoreanu
- Department of Pharmacology, University of Pittsburgh, School of Medicine, W1354 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
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Li Y, Ganta S, von Stein FB, Mason DE, Mitchell BM, Freeman LC. 4-aminopyridine decreases progesterone production by porcine granulosa cells. Reprod Biol Endocrinol 2003; 1:31. [PMID: 12740033 PMCID: PMC155641 DOI: 10.1186/1477-7827-1-31] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2003] [Accepted: 04/01/2003] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ion channels occur as large families of related genes with cell-specific expression patterns. Granulosa cells have been shown to express voltage-gated potassium channels from more than one family. The purpose of this study was to determine the effects of 4-aminopyridine (4-AP), an antagonist of KCNA but not KCNQ channels. METHODS Granulosa cells were isolated from pig follicles and cultured with 4-AP, alone or in combination with FSH, 8-CPT-cAMP, estradiol 17beta, and DIDS. Complimentary experiments determined the effects of 4-AP on the spontaneously established pig granulosa cell line PGC-2. Granulosa cell or PGC-2 function was assessed by radio-immunoassay of media progesterone accumulation. Cell viability was assessed by trypan blue exclusion. Drug-induced changes in cell membrane potential and intracellular potassium concentration were documented by spectrophotometric determination of DiBAC4(3) and PBFI fluorescence, respectively. Expression of proliferating cell nuclear antigen (PCNA) and steroidogenic acute regulatory protein (StAR) was assessed by immunoblotting. Flow cytometry was also used to examine granulosa cell viability and size. RESULTS 4-AP (2 mM) decreased progesterone accumulation in the media of serum-supplemented and serum-free granulosa cultures, but inhibited cell proliferation only under serum-free conditions. 4-AP decreased the expression of StAR, the production of cAMP and the synthesis of estradiol by PGC-2. Addition of either 8-CPT-cAMP or estradiol 17beta to serum-supplemented primary cultures reduced the inhibitory effects of 4-AP. 4-AP treatment was also associated with increased cell size, increased intracellular potassium concentration, and hyperpolarization of resting membrane potential. The drug-induced hyperpolarization of resting membrane potential was prevented either by decreasing extracellular chloride or by adding DIDS to the media. DIDS also prevented 4-AP inhibition of progesterone production. CONCLUSION 4-AP inhibits basal and FSH-stimulated progesterone production by pig granulosa cells via drug action at multiple interacting steps in the steroidogenic pathway. These inhibitory effects of 4-AP on steroidogenesis may reflect drug-induced changes in intracellular concentrations of K+and Cl- as well as granulosa cell resting membrane potential.
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Affiliation(s)
- Yan Li
- Departments of Anatomy & Physiology College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5802, USA
| | - Suhasini Ganta
- Departments of Anatomy & Physiology College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5802, USA
| | - Fred B von Stein
- Departments of Anatomy & Physiology College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5802, USA
| | - Diane E Mason
- Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5802, USA
| | - Brianna M Mitchell
- Departments of Anatomy & Physiology College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5802, USA
| | - Lisa C Freeman
- Departments of Anatomy & Physiology College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5802, USA
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Amberg GC, Koh SD, Imaizumi Y, Ohya S, Sanders KM. A-type potassium currents in smooth muscle. Am J Physiol Cell Physiol 2003; 284:C583-95. [PMID: 12556357 DOI: 10.1152/ajpcell.00301.2002] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A-type currents are voltage-gated, calcium-independent potassium (Kv) currents that undergo rapid activation and inactivation. Commonly associated with neuronal and cardiac cell-types, A-type currents have also been identified and characterized in vascular, genitourinary, and gastrointestinal smooth muscle cells. This review examines the molecular identity, biophysical properties, pharmacology, regulation, and physiological function of smooth muscle A-type currents. In general, this review is intended to facilitate the comparison of A-type currents present in different smooth muscles by providing a comprehensive report of the literature to date. This approach should also aid in the identification of areas of research requiring further attention.
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Affiliation(s)
- Gregory C Amberg
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno 89557, USA
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