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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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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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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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