scholarly journals Expression of TASK and TREK, two-pore domain K+ channels, in human myometrium

Reproduction ◽  
2005 ◽  
Vol 129 (4) ◽  
pp. 525-530 ◽  
Author(s):  
Xilian Bai ◽  
George J Bugg ◽  
Susan L Greenwood ◽  
Jocelyn D Glazier ◽  
Colin P Sibley ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Pregnant Women ◽  
Human Myometrium ◽  
Rt Pcr ◽  
Excitable Cells ◽  
K Channels ◽  
Myometrial Cells ◽  
Channel Proteins ◽  
A Site ◽  
Pore Domain

Two-pore domain K+channels are an emerging family of K+channels that may contribute to setting membrane potential in both electrically excitable and non-excitable cells and, as such, influence cellular function. The human uteroplacental unit contains both excitable (e.g. myometrial) and non-excitable cells, whose function depends upon the activity of K+channels. We have therefore investigated the expression of two members of this family, TWIK (two-pore domain weak inward rectifying K+channel)-related acid-sensitive K+channel (TASK) and TWIK-related K+channel (TREK) in human myometrium. Using RT-PCR the mRNA expression of TASK and TREK isoforms was examined in myometrial tissue from pregnant women. mRNAs encoding TASK1, 4 and 5 and TREK1 were detected whereas weak or no signals were observed for TASK2, TASK3 and TREK2. Western blotting for TASK1 gave two bands of approximately 44 and 65 kDa, whereas TREK1 gave bands of approximately 59 and 90 kDa in myometrium from pregnant women. TASK1 and TREK1 immunofluorescence was prominent in intracellular and plasmalemmal locations within myometrial cells. Therefore, we conclude that the human myometrium is a site of expression for the two-pore domain K+channel proteins TASK1 and TREK1.

269 EXPRESSION OF TANDEM-PORE DOMAIN K+ CHANNELS IN BOVINE OOCYTES AND PRE-IMPLANTATION EMBRYOS

2007 ◽  
Vol 19 (1) ◽  
pp. 251
Author(s):  
C. G. Hur ◽  
D. Kang ◽  
J. Y. Park ◽  
S. G. Hong ◽  
J. Han
Keyword(s):  
Germinal Vesicle ◽  
Human Myometrium ◽  
Resting Membrane Potential ◽  
Rt Pcr ◽  
Cellular Functions ◽  
Cell Stage ◽  
K Channels ◽  
Task Channels ◽  
Pore Domain ◽  
Bovine Oocytes

Tandem-pore domain K+ (K2P) channels that contribute to setting the resting membrane potential of excitable and nonexcitable cells are expressed in many kinds of cells and tissues. Recent studies have shown that TASK [TWIK (Tandem of P domains in Weak Inward rectifying K+ channels)-related acid-sensitive K+ channels] and TREK (TWIK-Related K+ channels), members of K2P channel family that are involved in a variety of cellular functions, are expressed in human myometrium, placenta, and cytotrophoblast cells. However, their expression in bovine oocytes and embryos has not yet been reported. In this study, we examined whether TASK and TREK channels are expressed in bovine immature (germinal vesicle-stage) and mature (metaphase II-stage) oocytes and in pre-implantation (2-cell- and 16-cell-stage) embryos using RT-PCR and immunocytochemistry. RT-PCR data showed that TASK-1, TASK-3, TREK-1, TREK-2, and TRAAK channels were expressed in bovine immature and mature oocytes. Interestingly, the expression levels of TREK channels were 2-fold higher than those of TASK channels as judged by semiquantitative RT-PCR and real-time PCR with cDNA synthesized from 50 individual immature and mature oocytes (P < 0.05, n = 4). Intensity of genes was normalized with respect to that of GAPDH. Consistent with RT-PCR data, immunocytochemical data showed that TASK-1, TASK-3, TREK-1, TREK-2, and TRAAK channels were expressed in bovine immature and mature oocytes. The fluorescence intensity of TREK channels was higher than that of TASK channels (P < 0.05, n = 5). TASK and TREK channels were also expressed in pre-implantation embryos. Of TREK channels, the TREK-2 channel was strongly expressed in immature and mature oocytes and in pre-implantation embryos (P < 0.05, n = 5). For statistics, Student's t-test was used, with P < 0.05 as the criterion for significance. Our results show that TASK-1, TASK-3, TREK-1, TREK-2, and TRAAK channels were expressed in bovine immature and mature oocytes and pre-implantation embryos. These results suggest that TASK and TREK channels could be involved in various physiological processes in mammalian oocytes and embryos.

scholarly journals Time-irreversible Subconductance Gating Associated with Ba2+ Block of Large Conductance Ca2+-activated K+ Channels

1998 ◽  
Vol 111 (2) ◽  
pp. 343-362 ◽  
Author(s):  
Ricardo A. Bello ◽  
Karl L. Magleby
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
External Solution ◽  
Single Step ◽  
Rat Skeletal Muscle ◽  
Patch Clamp Technique ◽  
K Channels ◽  
Open Time ◽  
Channel Open Time ◽  
A Site

Ba2+ block of large conductance Ca2+-activated K+ channels was studied in patches of membrane excised from cultures of rat skeletal muscle using the patch clamp technique. Under conditions in which a blocking Ba2+ ion would dissociate to the external solution (150 mM N-methyl-d-glucamine+o, 500 mM K+i, 10 μM Ba2+i, +30 mV, and 100 μM Ca2+i to fully activate the channel), Ba2+ blocks with a mean duration of ∼2 s occurred, on average, once every ∼100 ms of channel open time. Of these Ba2+ blocks, 78% terminated with a single step in the current to the fully open level and 22% terminated with a transition to a subconductance level at ∼0.26 of the fully open level (preopening) before stepping to the fully open level. Only one apparent preclosing was observed in ∼10,000 Ba2+ blocks. Thus, the preopenings represent Ba2+-induced time-irreversible subconductance gating. The fraction of Ba2+ blocks terminating with a preopening and the duration of preopenings (exponentially distributed, mean = 0.75 ms) appeared independent of changes in [Ba2+]i or membrane potential. The fractional conductance of the preopenings increased from 0.24 at +10 mV to 0.39 at +90 mV. In contrast, the average subconductance level during normal gating in the absence of Ba2+ was independent of membrane potential, suggesting different mechanisms for preopenings and normal subconductance levels. Preopenings were also observed with 10 mM Ba2+o and no added Ba2+i. Adding K+, Rb+, or Na+ to the external solution decreased the fraction of Ba2+ blocks with preopenings, with K+ and Rb+ being more effective than Na+. These results are consistent with models in which the blocking Ba2+ ion either induces a preopening gate, and then dissociates to the external solution, or moves to a site located on the external side of the Ba2+ blocking site and acts directly as the preopening gate.

scholarly journals Reciprocal Feedback Between miR-181a and E2/ERα in Myometrium Enhances Inflammation Leading to Labor

2016 ◽  
Vol 101 (10) ◽  
pp. 3646-3656 ◽  
Author(s):  
Lu Gao ◽  
Gang Wang ◽  
Wei-Na Liu ◽  
Holly Kinser ◽  
Hector L. Franco ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Cesarean Section ◽  
Pregnant Women ◽  
Preterm Labor ◽  
Elective Cesarean Section ◽  
Human Myometrium ◽  
Myometrial Cells ◽  
Emergency Cesarean ◽  
Tnf Α ◽  
Estradiol 17Β

Context: The initiation of term and preterm labor is associated with an up-regulated inflammatory response in myometrium; however, the underlying signaling pathways remain incompletely defined. Objective: To define the regulatory mechanisms that mediate the increased myometrial inflammatory response leading to labor, we investigated the roles of microRNAs (miRNA/miR). Design and Setting: Human myometrial tissues, isolated smooth muscle cells, and animal models were used to study miR-181a regulation of uterine inflammatory pathways and contractility. Patients: Myometrial tissues from 15 term pregnant women undergoing elective cesarean section (not in labor) and 10 term pregnant women undergoing emergency cesarean section (in labor) were used. Results: Expression of the highly conserved microRNA, miR-181a, was significantly decreased in mouse and human myometrium during late gestation. By contrast, the putative miR-181a targets, TNF-α, and estrogen receptor (ER)-α, and the validated target, c-Fos, key factors in the inflammatory response leading to parturition, were coordinately up-regulated. In studies using human myometrial cells, overexpression of miR-181a mimics repressed basal as well as IL-1β-induced TNF-α, C-C motif chemokine ligand 2 and 8 expression, whereas the expression of the antiinflammatory cytokine, IL-10, was increased. Overexpression of miR-181a dramatically inhibited both spontaneous and IL-1β-induced contraction of human myometrial cells. Notably, miR-181a directly targeted ERα and decreased its expression, whereas estradiol-17β reciprocally inhibited expression of mature miR-181a in myometrial cells. Conclusions: Thus, increased estradiol-17β/ERα signaling in myometrium near term inhibits miR-181a, resulting in a further increase in ERα and proinflammatory signaling. This escalating feedback loop provides novel targets and therapeutic strategies for the prevention of preterm labor and its consequences.

Lipids and two-pore domain K+ channels in excitable cells

2005 ◽  
Vol 77 (1-4) ◽  
pp. 103-110 ◽  
Author(s):  
Alessandra Besana ◽  
Richard B. Robinson ◽  
Steven J. Feinmark
Keyword(s):  
Excitable Cells ◽  
K Channels ◽  
Pore Domain

scholarly journals Two-pore domain K+channels regulate membrane potential of isolated human articular chondrocytes

2011 ◽  
Vol 589 (21) ◽  
pp. 5071-5089 ◽  
Author(s):  
Robert B. Clark ◽  
Colleen Kondo ◽  
Darrell D. Belke ◽  
Wayne R. Giles
Keyword(s):  
Membrane Potential ◽  
Articular Chondrocytes ◽  
Human Articular Chondrocytes ◽  
K Channels ◽  
Pore Domain

scholarly journals Membrane-delimited Inhibition of Maxi-K Channel Activity by the Intermediate Conductance Ca2+-activated K Channel

2006 ◽  
Vol 127 (2) ◽  
pp. 159-169 ◽  
Author(s):  
Jill Thompson ◽  
Ted Begenisich
Keyword(s):  
Single Channel ◽  
Expression System ◽  
Chemical Activation ◽  
K Channel ◽  
Channel Activity ◽  
Single Family ◽  
Open Probability ◽  
K Channels ◽  
Channel Proteins ◽  
K Activity

The complexity of mammalian physiology requires a diverse array of ion channel proteins. This diversity extends even to a single family of channels. For example, the family of Ca2+-activated K channels contains three structural subfamilies characterized by small, intermediate, and large single channel conductances. Many cells and tissues, including neurons, vascular smooth muscle, endothelial cells, macrophages, and salivary glands express more than a single class of these channels, raising questions about their specific physiological roles. We demonstrate here a novel interaction between two types of Ca2+-activated K channels: maxi-K channels, encoded by the KCa1.1 gene, and IK1 channels (KCa3.1). In both native parotid acinar cells and in a heterologous expression system, activation of IK1 channels inhibits maxi-K activity. This interaction was independent of the mode of activation of the IK1 channels: direct application of Ca2+, muscarinic receptor stimulation, or by direct chemical activation of the IK1 channels. The IK1-induced inhibition of maxi-K activity occurred in small, cell-free membrane patches and was due to a reduction in the maxi-K channel open probability and not to a change in the single channel current level. These data suggest that IK1 channels inhibit maxi-K channel activity via a direct, membrane-delimited interaction between the channel proteins. A quantitative analysis indicates that each maxi-K channel may be surrounded by four IK1 channels and will be inhibited if any one of these IK1 channels opens. This novel, regulated inhibition of maxi-K channels by activation of IK1 adds to the complexity of the properties of these Ca2+-activated K channels and likely contributes to the diversity of their functional roles.

scholarly journals Role of Ca+-dependent K-channels in the membrane potential and contractility of aorta from spontaneously hypertensive rats

1994 ◽  
Vol 113 (3) ◽  
pp. 1022-1028 ◽  
Author(s):  
Eneida G. Silva ◽  
Eugenio Frediani-Neto ◽  
Alice T. Ferreira ◽  
Antonio CM. Paiva ◽  
Therezinha B. Paiva
Keyword(s):  
Membrane Potential ◽  
Spontaneously Hypertensive Rats ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
K Channels

Magnesium sulfate induces translocation of protein kinase C isoenzymes alpha and delta in myometrial cells from pregnant women

2004 ◽  
Vol 190 (2) ◽  
pp. 522-527 ◽  
Author(s):  
Miguel E. Bermeo ◽  
Victor P. Fomin ◽  
Gary Ventolini ◽  
Shawn G. Gibbs ◽  
David S. McKenna ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Pregnant Women ◽  
Magnesium Sulfate ◽  
Myometrial Cells ◽  
Kinase C

K channels in excitable cells as multi-ion pores

1979 ◽  
Vol 4 (1) ◽  
pp. 159-162 ◽  
Author(s):  
Bertil Hille ◽  
Wolfgang Schwarz
Keyword(s):  
Excitable Cells ◽  
K Channels
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