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Almohanna AM, Noble K, Wray S. Extracellular acidification increases uterine contraction in pregnant mouse by increasing intracellular calcium. Acta Physiol (Oxf) 2024; 240:e14147. [PMID: 38650469 DOI: 10.1111/apha.14147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 03/07/2024] [Accepted: 04/05/2024] [Indexed: 04/25/2024]
Abstract
AIMS As uterine extracellular pH decreases during the ischemic conditions of labor, but its effects on myometrial contraction are largely unknown, there is a need to elucidate its physiological effects and mechanisms of action. Furthermore, it is not known if any of the effects of extracellular acidification are affected by pregnancy, thus we also determined how gestation affects the response to acidification. METHODS Nonpregnant, mid-, and term-pregnant myometrial strips were obtained from humanely killed mice. Contractions were recorded under spontaneous, depolarized, and oxytocin-stimulated conditions. The extracellular pH of the perfusate was changed from 7.4 to 6.9 or 7.9 in HEPES-buffered physiological saline. Intracellular pH was measured using SNARF, and intracellular calcium was measured using Indo-1. Statistical differences were tested using the appropriate t-test. RESULTS Extracellular acidification significantly increased the frequency and amplitude of spontaneous contractions in pregnant, but not nonpregnant, myometrium, whereas alkalinization decreased contractions. Intracellular acidification, via Na-butyrate, transiently increased force in pregnant tissue. Intracellular pH was gradually acidified when extracellular pH was acidified, but extracellular acidification increased contractility before any significant change in intracellular pH. If myometrial force was driven by oxytocin or high-K depolarization, then extracellular pH did not further increase force. Intracellular calcium changes mirrored those of force in the spontaneously contracting pregnant myometrium, and if calcium entry was prevented by nifedipine, extracellular acidification could not induce a rise in force. CONCLUSION Extracellular acidification increases excitability, calcium entry, and thus force in pregnant mouse myometrium, and this may contribute to increasing contractions during labor when ischemic conditions and acidemia occur.
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Affiliation(s)
- Asmaa M Almohanna
- Department of Basic Science, College of Medicine, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia
| | - Karen Noble
- Department of Veterinary Anatomy, Physiology and Pathology Institute of Infection, Veterinary and Ecological Sciences University of Liverpool, Liverpool, UK
| | - Susan Wray
- Department of Women and Children's Health, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
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2
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Garrett AS, Means SA, Roesler MW, Miller KJW, Cheng LK, Clark AR. Modeling and experimental approaches for elucidating multi-scale uterine smooth muscle electro- and mechano-physiology: A review. Front Physiol 2022; 13:1017649. [PMID: 36277190 PMCID: PMC9585314 DOI: 10.3389/fphys.2022.1017649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 09/21/2022] [Indexed: 11/13/2022] Open
Abstract
The uterus provides protection and nourishment (via its blood supply) to a developing fetus, and contracts to deliver the baby at an appropriate time, thereby having a critical contribution to the life of every human. However, despite this vital role, it is an under-investigated organ, and gaps remain in our understanding of how contractions are initiated or coordinated. The uterus is a smooth muscle organ that undergoes variations in its contractile function in response to hormonal fluctuations, the extreme instance of this being during pregnancy and labor. Researchers typically use various approaches to studying this organ, such as experiments on uterine muscle cells, tissue samples, or the intact organ, or the employment of mathematical models to simulate the electrical, mechanical and ionic activity. The complexity exhibited in the coordinated contractions of the uterus remains a challenge to understand, requiring coordinated solutions from different research fields. This review investigates differences in the underlying physiology between human and common animal models utilized in experiments, and the experimental interventions and computational models used to assess uterine function. We look to a future of hybrid experimental interventions and modeling techniques that could be employed to improve the understanding of the mechanisms enabling the healthy function of the uterus.
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Khan AA, Allemailem KS, Alhumaydhi FA, Gowder SJT, Rahmani AH. The Biochemical and Clinical Perspectives of Lactate Dehydrogenase: An Enzyme of Active Metabolism. Endocr Metab Immune Disord Drug Targets 2021; 20:855-868. [PMID: 31886754 DOI: 10.2174/1871530320666191230141110] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 11/05/2019] [Accepted: 11/25/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND Lactate dehydrogenase (LDH) is a group of oxidoreductase isoenzymes catalyzing the reversible reaction between pyruvate and lactate. The five isoforms of this enzyme, formed from two subunits, vary in isoelectric points and these isoforms have different substrate affinity, inhibition constants and electrophoretic mobility. These diverse biochemical properties play a key role in its cellular, tissue and organ specificity. Though LDH is predominantly present in the cytoplasm, it has a multi-organellar location as well. OBJECTIVE The primary objective of this review article is to provide an update in parallel, the previous and recent biochemical views and its clinical significance in different diseases. METHODS With the help of certain inhibitors, its active site three-dimensional view, reactions mechanisms and metabolic pathways have been sorted out to a greater extent. Overexpression of LDH in different cancers plays a principal role in anaerobic cellular metabolism, hence several inhibitors have been designed to employ as novel anticancer agents. DISCUSSION LDH performs a very important role in overall body metabolism and some signals can induce isoenzyme switching under certain circumstances, ensuring that the tissues consistently maintain adequate ATP supply. This enzyme also experiences some posttranslational modifications, to have diversified metabolic roles. Different toxicological and pathological complications damage various organs, which ultimately result in leakage of this enzyme in serum. Hence, unusual LDH isoform level in serum serves as a significant biomarker of different diseases. CONCLUSION LDH is an important diagnostic biomarker for some common diseases like cancer, thyroid disorders, tuberculosis, etc. In general, LDH plays a key role in the clinical diagnosis of various common and rare diseases, as this enzyme has a prominent role in active metabolism.
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Affiliation(s)
- Amjad A Khan
- Department of Basic Health Sciences, College of Applied Medical Science, Qassim University, Qassim, Saudi Arabia
| | - Khaled S Allemailem
- Department of Basic Health Sciences, College of Applied Medical Science, Qassim University, Qassim, Saudi Arabia,Department of Medical Laboratories, College of Applied Medical Science, Qassim University, Qassim, Saudi Arabia
| | - Fahad A Alhumaydhi
- Department of Medical Laboratories, College of Applied Medical Science, Qassim University, Qassim, Saudi Arabia
| | - Sivakumar J T Gowder
- Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City,
Vietnam,Faculty of Applied Sciences, Ton Duc Thang University, Vietnam
| | - Arshad H Rahmani
- Department of Medical Laboratories, College of Applied Medical Science, Qassim University, Qassim, Saudi Arabia
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4
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Sola-Leyva A, Andrés-León E, Molina NM, Terron-Camero LC, Plaza-Díaz J, Sáez-Lara MJ, Gonzalvo MC, Sánchez R, Ruíz S, Martínez L, Altmäe S. Mapping the entire functionally active endometrial microbiota. Hum Reprod 2021; 36:1021-1031. [PMID: 33598714 DOI: 10.1093/humrep/deaa372] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 12/11/2020] [Indexed: 12/13/2022] Open
Abstract
STUDY QUESTION Does endometrium harbour functionally active microorganisms and whether the microbial composition differs between proliferative and mid-secretory phases? SUMMARY ANSWER Endometrium harbours functionally alive microorganisms including bacteria, viruses, archaea and fungi whose composition and metabolic functions change along the menstrual cycle. WHAT IS KNOWN ALREADY Resident microbes in the endometrium have been detected, where microbial dysfunction has been associated with reproductive health and disease. Nevertheless, the core microorganismal composition in healthy endometrium is not determined and whether the identified bacterial DNA sequences refer to alive/functionally active microbes is not clear. Furthermore, whether there are cyclical changes in the microbial composition remains an open issue. STUDY DESIGN, SIZE, DURATION RNA sequencing (RNAseq) data from 14 endometrial paired samples from healthy women, 7 samples from the mid-secretory phase and 7 samples from the consecutive proliferative phase were analysed for the microbial RNA sequences. PARTICIPANTS/MATERIALS, SETTING, METHODS The raw RNAseq data were converted into FASTQ format using SRA Toolkit. The unmapped reads to human sequences were aligned to the reference database Kraken2 and visualised with Krona software. Menstrual phase taxonomic differences were performed by R package metagenomeSeq. The functional analysis of endometrial microbiota was obtained with HUMANn2 and the comparison between menstrual phases was conducted by one-way ANOVA. Human RNAseq analysis was performed using miARma-Seq and the functional enrichment analysis was carried out using gene set enrichment analysis (GSEA; HumanCyc). The integration of metabolic pathways between host and microbes was investigated. The developed method of active microbiota mapping was validated in independent sample set. MAIN RESULTS AND THE ROLE OF CHANCE With the novel metatranscriptomic approach, we mapped the entire alive microbiota composing of >5300 microorganisms within the endometrium of healthy women. Microbes such as bacteria, fungi, viruses and archaea were identified. The validation of three independent endometrial samples from different ethnicity confirmed the findings. Significant differences in the microbial abundances in the mid-secretory vs. proliferative phases were detected with possible metabolic activity in the host-microbiota crosstalk in receptive phase endometrium, specifically in the prostanoid biosynthesis pathway and L-tryptophan metabolism. LARGE SCALE DATA The raw RNAseq data used in the current study are available at GEO GSE86491 and at BioProject PRJNA379542. LIMITATIONS, REASONS FOR CAUTION These pioneering results should be confirmed in a bigger sample size. WIDER IMPLICATIONS OF THE FINDINGS Our study confirms the presence of active microbes, bacteria, fungi, viruses and archaea in the healthy human endometrium with implications in receptive phase endometrial functions, meaning that microbial dysfunction could impair the metabolic pathways important for endometrial receptivity. The results of this study contribute to the better understanding of endometrial microbiota composition in healthy women and its possible role in endometrial functions. In addition, our novel methodological pipeline for analysing alive microbes with transcriptional and metabolic activities could serve to inspire new analysis approaches in reproductive medicine. STUDY FUNDING/COMPETING INTERESTS This work is supported by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO) and European Regional Development Fund (FEDER): grants RYC-2016-21199 and ENDORE SAF2017-87526-R; FEDER/Junta de Andalucía-Consejería de Economía y Conocimiento: MENDO (B-CTS-500-UGR18) and by the University of Granada Plan Propio de Investigación 2016 - Excellence actions: Unit of Excellence on Exercise and Health (UCEES) (SOMM17/6107/UGR). A.S.-L. and N.M.M. are funded by the Spanish Ministry of Science, Innovation and Universities (PRE2018-0854409 and FPU19/01638). S.A. has received honoraria for lectures from Merck. The funder had no role in this study.
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Affiliation(s)
- Alberto Sola-Leyva
- Department of Biochemistry and Molecular Biology, Faculty of Sciences, University of Granada, Granada 18071, Spain.,Instituto de Investigación Biosanitaria ibs.GRANADA, Granada 18014, Spain
| | - Eduardo Andrés-León
- Unidad de Bioinformática, Instituto de Parasitología y Biomedicina "López-Neyra", CSIC (IPBLN-CSIC), Granada 18016, Spain
| | - Nerea M Molina
- Department of Biochemistry and Molecular Biology, Faculty of Sciences, University of Granada, Granada 18071, Spain.,Instituto de Investigación Biosanitaria ibs.GRANADA, Granada 18014, Spain
| | - Laura Carmen Terron-Camero
- Unidad de Bioinformática, Instituto de Parasitología y Biomedicina "López-Neyra", CSIC (IPBLN-CSIC), Granada 18016, Spain
| | - Julio Plaza-Díaz
- Instituto de Investigación Biosanitaria ibs.GRANADA, Granada 18014, Spain.,Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Granada 18071, Spain.,Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
| | - María José Sáez-Lara
- Department of Biochemistry and Molecular Biology, Faculty of Sciences, University of Granada, Granada 18071, Spain.,Instituto de Investigación Biosanitaria ibs.GRANADA, Granada 18014, Spain.,Institute of Nutrition and Food Technology (INYTA), "José Mataix Verdú" Biomedical Research Centre (CIBM), University of Granada, Armilla, Granada 18016, Spain
| | - María Carmen Gonzalvo
- Instituto de Investigación Biosanitaria ibs.GRANADA, Granada 18014, Spain.,Unidad Reproducción, UGC Laboratorio clínico y UGC Obstetricia y Ginecología. Hospital Universitario Virgen de las Nieves, Granada 18014, Spain
| | - Rocío Sánchez
- Instituto de Investigación Biosanitaria ibs.GRANADA, Granada 18014, Spain.,Unidad Reproducción, UGC Laboratorio clínico y UGC Obstetricia y Ginecología. Hospital Universitario Virgen de las Nieves, Granada 18014, Spain
| | - Susana Ruíz
- Instituto de Investigación Biosanitaria ibs.GRANADA, Granada 18014, Spain.,Unidad Reproducción, UGC Laboratorio clínico y UGC Obstetricia y Ginecología. Hospital Universitario Virgen de las Nieves, Granada 18014, Spain
| | - Luís Martínez
- Instituto de Investigación Biosanitaria ibs.GRANADA, Granada 18014, Spain.,Unidad Reproducción, UGC Laboratorio clínico y UGC Obstetricia y Ginecología. Hospital Universitario Virgen de las Nieves, Granada 18014, Spain
| | - Signe Altmäe
- Department of Biochemistry and Molecular Biology, Faculty of Sciences, University of Granada, Granada 18071, Spain.,Instituto de Investigación Biosanitaria ibs.GRANADA, Granada 18014, Spain.,Competence Centre on Health Technologies, Tartu 50411, Estonia
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5
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Tomaiuolo R, Veneruso I, Cariati F, D’Argenio V. Microbiota and Human Reproduction: The Case of Female Infertility. High Throughput 2020; 9:ht9020012. [PMID: 32375241 PMCID: PMC7349014 DOI: 10.3390/ht9020012] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 04/24/2020] [Accepted: 04/28/2020] [Indexed: 12/14/2022] Open
Abstract
During the last decade, the availability of next-generation sequencing-based approaches has revealed the presence of microbial communities in almost all the human body, including the reproductive tract. As for other body sites, this resident microbiota has been involved in the maintenance of a healthy status. As a consequence, alterations due to internal or external factors may lead to microbial dysbiosis and to the development of pathologies. Female reproductive microbiota has also been suggested to affect infertility, and it may play a key role in the success of assisted reproductive technologies, such as embryo implantation and pregnancy care. While the vaginal microbiota is well described, the uterine microbiota is underexplored. This could be due to technical issues, as the uterus is a low biomass environment. Here, we review the state of the art regarding the role of the female reproductive system microbiota in women's health and human reproduction, highlighting its contribution to infertility.
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Affiliation(s)
- Rossella Tomaiuolo
- KronosDNA srl, Spinoff of Federico II University, 80133 Napoli, Italy; (R.T.); (F.C.)
- Department of Molecular Medicine and Medical Biotechnologies, Federico II University, Via Sergio Pansini 5, 80131 Napoli, Italy;
- CEINGE-Biotecnologie Avanzate scarl, Via Gaetano Salvatore 486, 80145 Napoli, Italy
| | - Iolanda Veneruso
- Department of Molecular Medicine and Medical Biotechnologies, Federico II University, Via Sergio Pansini 5, 80131 Napoli, Italy;
- CEINGE-Biotecnologie Avanzate scarl, Via Gaetano Salvatore 486, 80145 Napoli, Italy
| | - Federica Cariati
- KronosDNA srl, Spinoff of Federico II University, 80133 Napoli, Italy; (R.T.); (F.C.)
- CEINGE-Biotecnologie Avanzate scarl, Via Gaetano Salvatore 486, 80145 Napoli, Italy
| | - Valeria D’Argenio
- CEINGE-Biotecnologie Avanzate scarl, Via Gaetano Salvatore 486, 80145 Napoli, Italy
- Department of Human Sciences and Quality of Life Promotion, San Raffaele Open University, via di val Cannuta 247, 00166 Roma, Italy
- Correspondence: ; Tel.: +39-081-3737909
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6
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Arrowsmith S, Keov P, Muttenthaler M, Gruber CW. Contractility Measurements of Human Uterine Smooth Muscle to Aid Drug Development. J Vis Exp 2018. [PMID: 29443077 PMCID: PMC5841565 DOI: 10.3791/56639] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Discovery and characterization of novel pharmaceutical compounds or biochemical probes rely on robust and physiologically relevant assay systems. We describe methods to measure ex vivo myometrium contractility. This assay can be used to investigate factors and molecules involved in the modulation of myometrial contraction and to determine their excitatory or inhibitory actions, and hence their therapeutic potential in vivo. Biopsies are obtained from women undergoing cesarean section delivery with informed consent. Fine strips of myometrium are dissected, clipped and attached to a force transducer within 1 mL organ baths superfused with physiological saline solution at 37 °C. Strips develop spontaneous contractions within 2-3 h under set tension and remain stable for many hours (>6 h). Strips can also be stimulated to contract such as by the endogenous hormones, oxytocin and vasopressin, which cause concentration-dependent modulation of contraction frequency, force and duration, to more closely resemble contractions in labor. Hence, the effect of known and novel drug leads can be tested on spontaneous and agonist-induced contractions. This protocol specifically details how this assay can be used to determine the potency of known and novel agents by measuring their effects on various parameters of human myometrial contraction. We use the oxytocin- and V1a receptor antagonists, atosiban and SR49059 as examples of known compounds which inhibit oxytocin- and vasopressin-induced contractions, and demonstrate how this method can be used to complement and validate pharmacological data obtained from cell-based assays to aid drug development. The effects of novel agonists in comparison to oxytocin and vasopressin can also be characterized. Whilst we use the example of the oxytocin/ vasopressin system, this method can also be used to study other receptors and ion channels that play a role in uterine contraction and relaxation to advance the understanding of human uterine physiology and pathophysiology.
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Affiliation(s)
- Sarah Arrowsmith
- Harris-Wellbeing Preterm Birth Research Centre, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool;
| | - Peter Keov
- School of Biomedical Sciences, The University of Queensland
| | - Markus Muttenthaler
- Faculty of Chemistry, Institute of Biological Chemistry, University of Vienna; Institute for Molecular Bioscience, University of Queensland
| | - Christian W Gruber
- School of Biomedical Sciences, The University of Queensland; Center for Physiology and Pharmacology, Medical University of Vienna;
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7
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Kyeong KS, Hong SH, Kim YC, Cho W, Myung SC, Lee MY, You RY, Kim CH, Kwon SY, Suzuki H, Park YJ, Jeong EH, Kim HS, Kim H, Lim SW, Xu WX, Lee SJ, Ji IW. Myometrial relaxation of mice via expression of two pore domain acid sensitive K(+) (TASK-2) channels. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2016; 20:547-56. [PMID: 27610042 PMCID: PMC5015002 DOI: 10.4196/kjpp.2016.20.5.547] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 08/01/2016] [Accepted: 08/08/2016] [Indexed: 11/17/2022]
Abstract
Myometrial relaxation of mouse via expression of two-pore domain acid sensitive (TASK) channels was studied. In our previous report, we suggested that two-pore domain acid-sensing K+ channels (TASK-2) might be one of the candidates for the regulation of uterine circular smooth muscles in mice. In this study, we tried to show the mechanisms of relaxation via TASK-2 channels in marine myometrium. Isometric contraction measurements and patch clamp technique were used to verify TASK conductance in murine myometrium. Western blot and immunehistochemical study under confocal microscopy were used to investigate molecular identity of TASK channel. In this study, we showed that TEA and 4-AP insensitive non-inactivating outward K+ current (NIOK) may be responsible for the quiescence of murine pregnant longitudinal myometrium. The characteristics of NIOK coincided with two-pore domain acid-sensing K+ channels (TASK-2). NIOK in the presence of K+ channel blockers was inhibited further by TASK inhibitors such as quinidine, bupivacaine, lidocaine, and extracellular acidosis. Furthermore, oxytocin and estrogen inhibited NIOK in pregnant myometrium. When compared to non-pregnant myometrium, pregnant myometrium showed stronger inhibition of NIOK by quinidine and increased immunohistochemical expression of TASK-2. Finally, TASK-2 inhibitors induced strong myometrial contraction even in the presence of L-methionine, a known inhibitor of stretch-activated channels in the longitudinal myometrium of mouse. Activation of TASK-2 channels seems to play an essential role for relaxing uterus during pregnancy and it might be one of the alternatives for preventing preterm delivery.
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Affiliation(s)
- Kyu-Sang Kyeong
- Department of Obstetrics and Gynecology, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Seung Hwa Hong
- Department of Obstetrics and Gynecology, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Young Chul Kim
- Department Physiology, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Woong Cho
- Department of Pharmacology, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Sun Chul Myung
- Department of Urology, College of Medicine, Chung-Ang University, Seoul 06974, Korea
| | - Moo Yeol Lee
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul 06974, Korea
| | - Ra Young You
- Department Physiology, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Chan Hyung Kim
- Department of Pharmacology, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | | | - Hikaru Suzuki
- Department of Physiology, Nagoya City University Medical School, Nagoya 467-8601, Japan
| | - Yeon Jin Park
- Department of Obstetrics and Gynecology, Cheongju St. Mary's Hospital, Cheongju 28323, Korea
| | - Eun-Hwan Jeong
- Department of Obstetrics and Gynecology, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Hak Soon Kim
- Department of Obstetrics and Gynecology, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Heon Kim
- Department of Preventive Medicine, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Seung Woon Lim
- Department of Obstetrics and Gynecology, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Wen-Xie Xu
- Department of Physiology, Shanghai Jiaotong University, School of Medicine, Shanghai, 200240, P.R. China
| | - Sang Jin Lee
- Department of Medical Education, Chungbuk National University College of Medicine, Cheongju 28644, Korea
| | - Il Woon Ji
- Department of Obstetrics and Gynecology, Chungbuk National University College of Medicine, Cheongju 28644, Korea
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8
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Hanley JA, Weeks A, Wray S. Physiological increases in lactate inhibit intracellular calcium transients, acidify myocytes and decrease force in term pregnant rat myometrium. J Physiol 2015. [PMID: 26223765 PMCID: PMC4606541 DOI: 10.1113/jp270631] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Key points Lactate is increased in myometrial capillary blood from women in slow or non‐progressive labour (dystocia), suggesting that it is detrimental to uterine contractions. There are no studies of the effect of lactate on the myometrium. In the present study, we have investigated its effects and mechanism of action on myometrial strips from term pregnant rats. We show that lactate significantly decreased spontaneous contractility. Lactatedecreased pHi and inhibited Ca2+ transients. Nulling the decrease in pHi abolished the effects of lactate effects. If Ca2+ entry was enhanced, the effects of lactate were abolished. The present study suggests that the accumulation of extracellular lactate could contribute to labour dystocia.
Abstract Lactate is increased in myometrial capillary blood from women in slow or non‐progressive labour (dystocia), suggesting that it is detrimental to uterine contractions. There are, however, no studies of the effect of lactate on the myometrium. We therefore investigated its effects and mechanism of action on myometrial strips from term pregnant rats. The effects on spontaneous and oxytocin‐induced contractility in response to sodium lactate and other weak acids (1–20 mM) were studied. In some experiments, simultaneous force and intracellular Ca2+ or pH (pHi) were measured with Indo‐1 or Carboxy‐SNARF, respectively. Statistical differences were tested using non‐parametric tests. Lactate significantly decreased spontaneous contractility with an EC50 of 3.9 mM. Propionate, butyrate and pyruvate also reduced contractions with similar potency. The effects of lactate were reduced in the presence of oxytocin but remained significant. Lactate decreased pHi and nulling the decrease in pHi abolished its effects. We also show that lactate inhibited Ca2+ transients, with these changes mirroring those produced on force. If Ca2+ entry was enhanced by depolarization (high KCl) or applying the Ca2+ channel agonist, Bay K 4644, the effects of lactate were abolished. Taken together, these data show that lactate in the physiological range potently decreases myometrial contractility as a result of its inhibition of Ca2+ transients, which can be attributed to the induced acidification. The present study suggests that the accumulation of extracellular lactate will reduce myometrial contractions and could therefore contribute to labour dystocia.
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Affiliation(s)
| | - Andrew Weeks
- Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Susan Wray
- Departments of Cellular and Molecular Physiology
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9
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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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10
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Neal JL, Lowe NK, Corwin EJ. Serum lactate dehydrogenase profile as a retrospective indicator of uterine preparedness for labor: a prospective, observational study. BMC Pregnancy Childbirth 2013; 13:128. [PMID: 23759027 PMCID: PMC3687574 DOI: 10.1186/1471-2393-13-128] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 06/04/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Lactate dehydrogenase (LDH) isoenzymes are required for adenosine triphosphate production, with each of five different isoenzymes having varying proficiencies in anaerobic versus aerobic environments. With advancing pregnancy, the isoenzyme profile in uterine muscle shifts toward a more anaerobic profile, speculatively to facilitate uterine efficiency during periods of low oxygen that accompany labor contractions. Profile shifting may even occur throughout labor. Maternal serum LDH levels between 24-48 hours following delivery predominantly originate from uterine muscle, reflecting the enzymatic state of the myometrium during labor. Our purpose was to describe serum LDH isoenzymes 24-30 hours post-delivery to determine if cervical dilation rates following labor admission were associated with a particular LDH profile. We also compared differences in post-delivery LDH isoenzyme profiles between women admitted in pre-active versus established active labor. METHODS Low-risk, nulliparous women with spontaneous labor onset were sampled (n = 91). Maternal serum LDH was measured at labor admission and 24-30 hours post-vaginal delivery. Rates of cervical dilation during the first four hours after admission were also measured. Spearman's rho coefficients were used for association testing and t tests evaluated for group and paired-sample differences. RESULTS More efficient dilation following admission was associated with decreased LDH1 (p = 0.029) and increased LDH3 and LDH4 (p = 0.017 and p = 0.017, respectively) in the post-delivery period. Women admitted in established active labor had higher relative serum levels of LDH3 (t = 2.373; p = 0.023) and LDH4 (t = 2.268; p = 0.029) and lower levels of LDH1 (t = 2.073; p = 0.045) and LDH5 (t = 2.041; p = 0.048) when compared to women admitted in pre-active labor.Despite having similar dilatations at admission (3.4 ± 0.5 and 3.7 ± 0.6 cm, respectively), women admitted in pre-active labor had longer in-hospital labor durations (12.1 ± 4.3 vs. 5.3 ± 1.4 hours; p < 0.001) and were more likely to receive oxytocin augmentation (95.5% vs. 34.8%; p < 0.001). CONCLUSIONS More efficient cervical dilation following labor admission is associated with a more anaerobic maternal serum LDH profile in the post-delivery period. Since LDH profile shifting may occur throughout labor, watchful patience rather than intervention in earlier labor may allow LDH shifting within the uterus to more fully manifest. This may improve uterine efficiency during labor and decrease rates of oxytocin augmentation, thereby improving birth safety.
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Affiliation(s)
- Jeremy L Neal
- The Ohio State University, 1585 Neil Avenue, Columbus, OH, 43210, USA
| | - Nancy K Lowe
- Division of Women, Children, and Family Health in the College of Nursing, University of Colorado Denver, 13120 East 19th Avenue, Aurora, CO, 80045, USA
| | - Elizabeth J Corwin
- Nell Hodgson Woodruff School of Nursing, Emory University, 1520 Clifton Road NE, Atlanta, GA, 30322, USA
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11
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Lecarpentier ER, Claes VA, Timbely O, Arsalane A, Wipff JA, Hébert JLM, Michel FY, Lecarpentier YC. Mechanics and energetics of myosin molecular motors from nonpregnant human myometrium. J Appl Physiol (1985) 2011; 111:1096-105. [PMID: 21778420 DOI: 10.1152/japplphysiol.00414.2011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mechanical properties of spontaneously contracting isolated nonpregnant human myometrium (NPHM) were investigated throughout the whole continuum of load from zero load up to isometry. This made it possible to assess the three-dimensional tension-velocity-length (T-V-L) relationship characterizing the level of contractility and to determine crossbridge (CB) kinetics of myosin molecular motors. Seventy-seven muscle strips were obtained from hysterectomy in 42 nonpregnant patients. Contraction and relaxation parameters were measured during spontaneous mechanical activity. The isotonic tension-peak velocity (T-V) relationship was hyperbolic in 30 cases and nonhyperbolic in 47 cases. When the T-V relationship was hyperbolic, the Huxley formalism could be used to calculate CB kinetics and CB unitary force. At the whole muscle level and for a given isotonic load level, part of the V-L phase plane showed a common pathway, so that a given instantaneous length corresponded to only one possible instantaneous velocity, independent of time and initial length. At the molecular level, rate constants for CB attachment and detachment were dramatically low, ∼100 times lower than those of striated muscles, and ∼5 to 10 times lower than those of other smooth muscles. The CB unitary force was ∼1.4 ± 0.1 pN. NPHM shared similar basic contractile properties with striated muscles, reflected in the three-dimensional T-V-L relationship characterizing the contractile level. Low CB attachment and detachment rate constants made it possible to generate normal CB unitary force and normal muscle tension in NPHM, even though it contracted extremely slowly compared with other muscles.
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12
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Wiberg-Itzel E, Pettersson H, Andolf E, Hansson A, Winbladh B, Åkerud H. Lactate concentration in amniotic fluid: a good predictor of labor outcome. Eur J Obstet Gynecol Reprod Biol 2010; 152:34-8. [DOI: 10.1016/j.ejogrb.2010.05.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Revised: 03/24/2010] [Accepted: 05/13/2010] [Indexed: 11/29/2022]
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13
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Kupittayanant S, Kupittayanant P. The roles of pH in regulation of uterine contraction in the laying hens. Anim Reprod Sci 2009; 118:317-23. [PMID: 19647959 DOI: 10.1016/j.anireprosci.2009.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 07/01/2009] [Accepted: 07/07/2009] [Indexed: 11/17/2022]
Abstract
In the laying hens, the uterus (shell gland) plays essential roles in calcium transfer for calcification of the eggshell and expulsion of the egg through the vagina for oviposition. Much is known about the effects of pH changes on eggshell production of the uterus. However, very little is understood about the effects of pH changes on uterine contractility. We investigated the effects of pH changes on uterine contraction in the laying hens. The laying hens were humanely killed, and strips of uterine smooth muscles were isolated. Isometric force was measured and the effects of intracellular and extracellular pH changes studied. The results show that alterations of pH clearly have marked effects on force in the hen uterus. Both intracellular and extracellular acidifications significantly decreased uterine activity, whether it arises spontaneously or in the presence of agonists such as prostaglandin F(2alpha) and arachidonic acid. Alkalinization produced the opposite effects. Thus, changes in pH can regulate uterine contraction. This insight into pH regulation of the uterine activity provides a focus for egg production management directed at physiological and pathological oviposition in the laying hens.
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Affiliation(s)
- S Kupittayanant
- School of Physiology, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand.
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14
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Abstract
A better understanding of the mechanisms that generate and modulate uterine contractility is needed if progress is to be made in the prevention or treatment of problems in labour. Dysfunctional labour describes the condition when uterine contractility is too poor to dilate the cervix, and it is the leading cause of emergency Caesarean sections. Recently, insight has been gained into a possible causal mechanism for dysfunctional labour. Study of the physiological mechanisms that produce excitation in the uterus, the subsequent Ca(2)(+) signals and biochemical pathway leading to contraction has underpinned this progress. In this review, I give an account of excitation-contraction signalling in the myometrium and explore the implications of recent findings concerning lipid rafts for these processes. I also discuss how changes of pH are fundamentally enmeshed in uterine activity and biochemistry and explore the effect that pH changes will have on human myometrium. Finally, I present the evidence that acidification of the myometrium is correlated with dysfunctional labour and suggest the processes by which it is occurring. It is only by gaining a better understanding of uterine physiology and pathophysiology that progress will be made and research findings translated into clinical benefit for women and their families.
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Affiliation(s)
- Susan Wray
- Department of Physiology, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
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15
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Abstract
OBJECTIVE Inefficient uterine contractions are the most common cause of poor progress in labor. The global increase in cesarean delivery rate is a cause of considerable concern, and the greatest reason for increase is the result of failure to progress in labor. Following in vitro studies that showed acidification could depress uterine contraction, we hypothesized that it could contribute to dysfunctional labors. METHODS A blood sample was taken from the lower segment of the uterus from women having a cesarean delivery, either electively or as a result of dysfunctional labor, and from those having a normal labor. This blood sample was analyzed for pH, O(2) saturation, and lactate levels. Contraction was recorded in myometrial strips, taken from women having elective cesarean delivery, at the pH of normally and dysfunctionally contracting uteri. RESULTS The pH of myometrial capillary blood from women having a dysfunctional labor was significantly lower (7.35) than that from women having elective cesarean delivery (7.49) or cesarean delivery with normal contractions, with (7.47) or without (7.48) oxytocin (P <.001). The women in dysfunctional labor had higher capillary lactate and lower capillary O(2) saturation. Furthermore, in vitro, reducing the pH value from 7.5 to 7.3 changes regular uterine contractions to irregular ones of reduced amplitude. CONCLUSIONS Myometrial lactic acidosis and a small decrease in O(2) saturation may be contributing factors to dysfunctional labor. Our data may also account for the ineffectiveness in management of dysfunctional labor with oxytocin. Oxytocin with a background of lactate acidosis may not be successful. LEVEL OF EVIDENCE II-2
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Affiliation(s)
- Siobhan Quenby
- Department of Obstetrics and Gynaecology, University of Liverpool, Liverpool, United Kingdom.
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16
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Pierce SJ, Kupittayanant S, Shmygol T, Wray S. The effects of pH change on Ca(++) signaling and force in pregnant human myometrium. Am J Obstet Gynecol 2003; 188:1031-8. [PMID: 12712106 DOI: 10.1067/mob.2003.229] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE This study was designed to determine the effects of both intracellular and extracellular pH change on contractile activity and intracellular Ca(++) during spontaneous contractions, oxytocin, and depolarization-induced stimulation of human myometrium. STUDY DESIGN Human myometrial tissue was obtained at elective caesarean delivery at term (37-41 completed weeks of gestation). Longitudinal strips were dissected and loaded with the calcium sensitive indicator Indo-1. Statistical significance was tested with the Student t test. RESULTS Both intracellular and extracellular acidification significantly reduces or even abolishes phasic activity, whether it arises spontaneously or in the presence of oxytocin. These contractile changes can be accounted for by the changes in intracellular Ca(++). Alkalinization produced the opposite effects. However, baseline or maintained tension changes could not be accounted for by changes in intracellular Ca(++). CONCLUSION We suggest that the effects on phasic activity are due to the inhibition of L-type calcium entry and that, during maintained or baseline activity, pH-sensitive Ca(++) release, possibly from the sarcoplasmic reticulum occurs; but it is insufficient to overcome the inhibitory effects at the myofilaments. We conclude that alterations of pH significantly affect calcium signaling and force production in the human myometrium and may contribute to dysfunction in labor.
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Affiliation(s)
- S Joanne Pierce
- Department of Physiology, University of Liverpool, United Kingdom.
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17
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Young RC, Zhang P. The mechanism of propagation of intracellular calcium waves in cultured human uterine myocytes. Am J Obstet Gynecol 2001; 184:1228-34. [PMID: 11349193 DOI: 10.1067/mob.2001.113872] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The primary goal of this work was to determine the relative importance of sarcoplasmic reticulum inositol 1,4,5-triphosphate receptors and ryanodine receptors in the mechanism of intracellular calcium wave propagation in human uterine myocytes. A secondary goal was to identify the rate-determining step of calcium wave propagation. STUDY DESIGN Pregnant human myometrium was obtained at the time of cesarean delivery, enzymatically dispersed, and cultured through several passages. Intracellular calcium wave velocities were measured with video fluorescence microscopy and the calcium-dependent fluorescent dye calcium green 1. Experimental conditions were modified by exposure of the cells to ruthenium red (blocked ryanodine receptor), ryanodine (locked open ryanodine receptor), oxytocin (increased inositol-1,4,5-triphosphate), sodium butyrate (intracellular acidification), ammonium chloride (intracellular alkalinization), and elevation of temperature (from 19 degrees C to 30 degrees C). RESULTS Wave velocities were found to be the same for spontaneously occurring (9.6 +/- 2.6 microm/s) and oxytocin-stimulated (10.3 +/- 3.4 microm/s) waves. Advance treatment of the cells with ryanodine or ruthenium red failed to change oxytocin-stimulated wave velocities from control values. The temperature dependence of calcium wave velocities was studied across the range 19 degrees C to 30 degrees C. Plots of wave velocities versus the inverse of the temperature yielded apparent activation energies that were the same for spontaneous (13.2 +/- 0.3 kcal/mol) and oxytocin-induced (14.3 +/- 1.6 kcal/mol) waves. After intracellular acidification by treatment with butyrate (20 mmol/L) wave velocities increased by 44%. Wave velocities decreased by 35% after treatment with ammonium chloride (20 mmol/L). CONCLUSION Propagation of intracellular calcium waves in cultured human uterine myocytes exhibited mechanisms of sarcoplasmic reticulum calcium release that could use either inositol 1,4,5-triphosphate receptors alone or ryanodine receptors alone, or both together. The rate-determining step for calcium wave propagation was diffusion of calcium though a highly buffered cytoplasm.
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Affiliation(s)
- R C Young
- Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, USA
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18
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Krieger TR, Loch-Caruso R. Antioxidants prevent gamma-hexachlorocyclohexane-induced inhibition of rat myometrial gap junctions and contractions. Biol Reprod 2001; 64:537-47. [PMID: 11159356 DOI: 10.1095/biolreprod64.2.537] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Lindane (gamma-hexachlorocyclohexane) is a commonly used pesticide that bioaccumulates in mammalian adipose tissue. Lindane inhibits gap junctional intercellular communication and oscillatory contractions of pregnant rat myometrium in vitro. The present study investigated the role of oxidative stress in lindane's inhibition of myometrial function in mid-gestation pregnant rat uteri. Lucifer yellow dye was microinjected into cultured myocytes to assess gap junctional intercellular communication. Lindane exposure (100 microM) resulted in a time-dependent, biphasic inhibition of dye transfer. This pattern of inhibition was also seen upon cell exposure to the pro-oxidant, tert-butyl hydroperoxide (100 microM). Lindane's initial and secondary-onset dye transfer inhibitions were reversed by cotreatment and pretreatment with the antioxidants, alpha-tocopherol (25-100 microM), diphenyl-1,4-phenylene diamine (10-30 microM), and superoxide dismutase (100-400 U/ml). D-mannitol (100-300 mM) also reversed lindane's initial dye transfer inhibition. Nitro blue tetrazolium reduction to formazan (measured spectrophotometrically) was elevated upon exposure of cultured cells to lindane or tert-butyl hydroperoxide, indicating the presence of reducing agents. Lipid peroxidation, assessed as thiobarbituric acid-reactive substances, was also elevated in lindane-exposed cell cultures. alpha-Tocopherol reversed this elevation. Finally, uterine contractility was assessed by measuring isometric contractions of uterine strips hung in standard muscle baths. Pretreatment with alpha-tocopherol prevented lindane's abolishment of uterine contractions in vitro. These data support the hypothesis that lindane inhibits uterine contractility and myometrial gap junctions by establishing an oxidative stress environment.
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Affiliation(s)
- T R Krieger
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI 48109-2029, USA
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Peña A, Johannisson A, Linde-Forsberg C. Post-thaw evaluation of dog spermatozoa using new triple fluorescent staining and flow cytometry. Theriogenology 1999; 52:965-80. [PMID: 10735104 DOI: 10.1016/s0093-691x(99)00186-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A new triple fluorescent staining method was developed to evaluate frozen-thawed dog spermatozoa. This method was used to compare functional parameters of canine spermatozoa cryopreserved using 2 different freezing-thawing protocols. One ejaculate from each of 10 dogs was split into 2 aliquots and processed using the Andersen method or the CLONE method. Semen samples were evaluated immediately after thawing and after 3 h of incubation at 37 degrees C. Plasma membrane integrity and acrosomal status of the spermatozoa were evaluated simultaneously by flow cytometry using a combination of 3 fluorescent dyes: Carboxy-SNARF-1 (SNARF), to identify the live spermatozoa; propidium iodide (PI), which only stains dead cells or cells with damaged membranes; and fluorescein isothiocyanate (FITC)-conjugated Pisum sativum agglutinin (PSA), which binds to the acrosomal content of spermatozoa with damaged plasma and outer acrosomal membranes. The accuracy of this new staining method in quantifying the proportions of live and dead spermatozoa by flow cytometry was evaluated by comparing it with the staining technique using carboxyfluorescein diacetate and propidium iodide (CFDA-PI), which yielded high correlation coefficients. The triple-stained sperm samples were also analyzed by epifluorescence microscopy, and both methods proved to be highly correlated. Post-thaw progressive motility and plasma membrane integrity were similar for the 2 freezing procedures, but the proportion of damaged acrosomes after thawing was lower using the Andersen method and the spermatozoa had a higher thermoresistance. This new triple staining method for assessing canine sperm viability and acrosomal integrity provides an efficient procedure for evaluating frozen-thawed dog semen samples either by flow cytometry or fluorescence microscopy.
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Affiliation(s)
- A Peña
- Department of Obstetrics and Gynaecology, Swedish University of Agricultural Sciences, Uppsala, Sweden
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20
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Taggart MJ, Sheader EA, Walker SD, Naderali EK, Moore S, Wray S. External alkalinization decreases intracellular Ca++ and spontaneous contractions in pregnant rat myometrium. Am J Obstet Gynecol 1997; 177:959-63. [PMID: 9369852 DOI: 10.1016/s0002-9378(97)70301-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVES As plasma pH rises during pregnancy, the effect of raising external pH on spontaneous contractions in pregnant rat myometrium was investigated to test the hypothesis that elevated external pH depresses contraction. STUDY DESIGN Strips of longitudinal myometrium were loaded with SNARF (seminaphthorhodafluor) or Indo-1 for simultaneous intracellular pH or Ca++ and force measurements. Results were obtained from a minimum of five animals in each group, and significant differences were tested for by paired Student t tests. RESULTS Raising the external pH significantly reduced spontaneous force and calcium transient in the pregnant uterus. Raising the external pH led to a slow rise in intracellular pH, but this could not account for the functional effect. K+ rubidium 86-labeled efflux rates were unaffected by external pH, suggesting no hyperpolarization. The Ca++ channel agonist Bay K8644 (5 mumol/L) restored contractions abolished by raised external pH. CONCLUSIONS Raised external pH reduces spontaneous contractions in the pregnant rat uterus, probably by an external effect on Ca++ entry. This effect may contribute to uterine quiescence before term.
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Affiliation(s)
- M J Taggart
- Physiological Laboratory, University of Liverpool, United Kingdom
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21
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Parratt JR, Taggart MJ, Wray S. Changes in intracellular pH close to term and their possible significance to labour. Pflugers Arch 1995; 430:1012-4. [PMID: 8594535 DOI: 10.1007/bf01837416] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The contractile pattern of uterine smooth muscle is markedly altered by even modest manipulations of intracellular pH (pHi); an acidification can abolish contractions, while alkalinization increases contractility. As at the end of gestation the uterus changes from being relatively quiescent to highly contractile, we investigated whether pHi changes with pregnancy in women. Isolated tissue was loaded with the pH-sensitive fluorophore, carboxy-SNARF. We found a significant alkalinization over the last few weeks of pregnancy. Such an increase in pHi will increase contractility of the uterus, and may therefore contribute to the mechanisms ensuring strong and efficient contractions occur during labour.
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Affiliation(s)
- J R Parratt
- The Physiological Laboratory, The University of Liverpool, PO Box 147, Liverpool L69 3BX, UK
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