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stretch channels

Yi-Ying Wang, Manas Ranjan Dash, Chao-Yu Chung, Yuan-Pern Lee
We recorded time-resolved infrared absorption spectra of transient species produced on irradiation at 308 nm of a flowing mixture of CH 2 I 2 /O 2 /N 2 /SO 2 at 298 K. Bands of CH 2 OO were observed initially upon irradiation; their decrease in intensity was accompanied by the appearance of an intense band at 1391.5 cm -1 that is associated with the degenerate SO-stretching mode of SO 3 , two major bands of HCHO at 1502 and 1745 cm -1 , and five new bands near >1340, 1225, 1100, 940, and 880 cm -1 . The band near 1340 cm -1 was interfered by absorption of SO 2 and SO 3 , so its band maximum might be greater than 1340 cm -1 ...
February 14, 2018: Journal of Chemical Physics
Hailin Zhao, Daiqian Xie, Hua Guo
Photodetachment of the ClH 2 O - anion is investigated using full-dimensional quantum mechanics on accurate potential energy surfaces of both the anion and neutral species. Detailed analysis of the photoelectron spectrum and the corresponding wavefunctions reveals that the photodetachment leads to, in the product channel of the exothermic HCl + OH → Cl + H 2 O reaction, the formation of numerous Feshbach resonances due apparently to slow energy transfer from H 2 O vibrational modes to the dissociation coordinate...
February 14, 2018: Journal of Chemical Physics
Li He, Guangwei Si, Jiuhong Huang, Aravinthan D T Samuel, Norbert Perrimon
Somatic stem cells constantly adjust their self-renewal and lineage commitment by integrating various environmental cues to maintain tissue homeostasis. Although numerous chemical and biological signals have been identified that regulate stem-cell behaviour, whether stem cells can directly sense mechanical signals in vivo remains unclear. Here we show that mechanical stress regulates stem-cell differentiation in the adult Drosophila midgut through the stretch-activated ion channel Piezo. We find that Piezo is specifically expressed in previously unidentified enteroendocrine precursor cells, which have reduced proliferation ability and are destined to become enteroendocrine cells...
February 7, 2018: Nature
Tomáš Bleha, Peter Cifra
Mechanical deformation of dsDNA molecules inside square nanochannels is investigated using simulations based on a coarse-grained model of DNA. The combined action of confinement and weak external forces is explored in a variety of confinement regimes, including the transition zone relevant to nanofluidic experiments. The computed free energy and force profiles are markedly affected by the channel size. Effective elastic softening of confined DNA molecules relative to the bulk DNA is observed in the channels of intermediate widths...
January 24, 2018: Soft Matter
Martha Rocio Servin-Vences, Jessica Richardson, Gary R Lewin, Kate Poole
Cartilage tissue lines the joints of mammals, helping to lubricate joint movement and distribute mechanical loads. This tissue is comprised of isolated cells known as chondrocytes which are embedded in an extracellular matrix. Chondrocytes produce and maintain the cartilage by sensing and responding to changing mechanical loads. Mechanosensitive ion channels have been implicated in chondrocyte mechanotransduction and recent studies have shown that both PIEZO1 and TRPV4 can be activated by mechanical stimuli in these cells...
January 23, 2018: Clinical and Experimental Pharmacology & Physiology
Ani Amar, Sharon Zlochiver, Ofer Barnea
Mechano-electric feedback affects the electrophysiological and mechanical function of the heart and the cellular, tissue, and organ properties. To determine the main factors that contribute to this effect, this study investigated the changes in the action potential characteristics of the ventricle during contraction. A model of stretch-activated channels was incorporated into a three-dimensional multiscale model of the contracting ventricle to assess the effect of different preload lengths on the electrophysiological behavior...
2018: PloS One
Constanze Schmidt, Rémi Peyronnet
Ion channels are essential for electrical signaling and contractility in cardiomyocytes. Detailed knowledge about the molecular function and regulation of cardiac ion channels is crucial for understanding cardiac physiology and pathophysiology especially in the field of arrhythmias. This review aims at providing a general overview on the identity, functional characteristics, and roles of voltage-gated as well as stretch-activated potassium selective channels in the heart. In particular, we will highlight potential therapeutic targets as well as the emerging fields of future investigations...
January 5, 2018: Herzschrittmachertherapie & Elektrophysiologie
Nagarajan Muthialu
Cardiac variant of total anomalous pulmonary venous return is a rare entity, whereby all the pulmonary veins drain directly to the right atrium or coronary sinus. The effective left heart blood flow channels through a small stretched patent foramen ovale and can often be confused with a variant of cor triatriatum. Cor triatriatum is a rare congenital cardiac anomaly where pulmonary veins drain to a persistent chamber above the left atrium with a membrane separating these two. There persists either a small aperture directly from the true to the accessory left atrium or none at all...
January 2018: Journal of the Saudi Heart Association
Eileen Nicole Shimizu, Jennifer L Seifert, Kevin J Johnson, Mario Romero-Ortega
Spinal cord injury (SCI) without radiographic abnormalities (SCIWORA) presents a significant challenge due the loss of function despite an apparent normal anatomy. The cause of dysfunction is not understood and specific treatment options are lacking. Some scoliosis corrective surgeries result in SCIWORA, where stretching of the spinal cord can lead to vascular compromise and hypoxia. This procedure allows for the implantation of neuroprotective strategies designed to prevent iatrogenic SCI. We utilized a model of atraumatic SCI to evaluate the efficacy of the sodium channel blocker Riluzole, as a prophylactic neuroprotectant...
January 2, 2018: Journal of Neurotrauma
Andrea Buccarello, Michela Azzarito, Frédéric Michoud, Stéphanie P Lacour, Jan P Kucera
AIM: Cardiac tissue deformation can modify tissue resistance, membrane capacitance and ion currents, and hence cause arrhythmogenic slow conduction. Our aim was to investigate whether uniaxial strain causes different changes in conduction velocity (θ) when the principal strain axis is parallel vs. perpendicular to impulse propagation. METHODS: Cardiomyocyte strands were cultured on stretchable custom microelectrode arrays and θ was determined during steady-state pacing...
December 28, 2017: Acta Physiologica
Zhiguo Zhang, Yuqiao Wen, Jing Du, Yang Yu, Sisi Liu, Xiaoan Wu, Hucheng Zhao
It is well recognized that pathologically increased mechanical stretch plays a critical role in vascular remodeling during hypertension. However, how the stretch modulates the functions of ion channels of vascular smooth muscle cells (VSMCs) remains to be elucidated. Here, we demonstrated the effects of mechanical stretch on the activity of large conductance calcium, voltage-activated potassium (BK) and L-type Ca2+channels. In comparison with 5% stretch (physiological), 15% stretch (pathological) upregulated the current density of L-type Ca2+and BK channels as well as the frequency and amplitude of calcium oscillation in VSMCs...
January 23, 2018: Journal of Biomechanics
María Laura Barberini, Lorena Sigaut, Weijie Huang, Silvina Mangano, Silvina Paola Denita Juarez, Eliana Marzol, José Estevez, Mariana Obertello, Lía Pietrasanta, Weihua Tang, Jorge Muschietti
In vitro tomato pollen tubes show a cytoplasmic calcium gradient that oscillates with the same period as growth. Pollen tube growth requires coordination between the tip-focused cytoplasmic calcium concentration ([Ca2+]cyt) gradient and the actin cytoskeleton. This [Ca2+]cyt gradient is necessary for exocytosis of small vesicles, which contributes to the delivery of new membrane and cell wall at the pollen tube tip. The mechanisms that generate and maintain this [Ca2+]cyt gradient are not completely understood...
December 13, 2017: Plant Reproduction
Andrey Khaitin, Mikhail Rudkovskii, Anatoly Uzdensky
Severe nerve injury such as axotomy induces neuron degeneration and death of surrounding glial cells. Using a crayfish stretch receptor that consists of a single mechanoreceptor neuron enveloped by satellite glia, we showed that axotomy not only mechanically injures glial cells at the transection location, but also induces necrosis or apoptosis of satellite glial cells remote from the transection site. We studied Ca2+role in spontaneous or axotomy-induced death of remote glial cells. Stretch receptors were isolated using the original technique that kept the neuron connected to the ventral cord ganglion (control preparations)...
December 7, 2017: Molecular and Cellular Neurosciences
Yoshio Takemoto, Rafael J Ramirez, Kuljeet Kaur, Oscar Salvador-Montañés, Daniela Ponce-Balbuena, Roberto Ramos-Mondragón, Steven R Ennis, Guadalupe Guerrero-Serna, Omer Berenfeld, José Jalife
BACKGROUND: The aldosterone inhibitor eplerenone (EPL) has been shown to reduce the incidence of atrial fibrillation (AF) in patients with systolic heart failure, but the mechanism is unknown. OBJECTIVES: This study hypothesized that by reducing atrial dilation and fibrosis in the absence of heart failure, EPL also reduces AF burden and prevents AF perpetuation. METHODS: The authors conducted a randomized controlled study in 34 sheep that were atrially tachypaced (13 ± 1 week)...
December 12, 2017: Journal of the American College of Cardiology
Sonia M O'Kelly, Zena Eh Moore
BACKGROUND: The female perineum becomes suffused and stretched during pregnancy, and further strain during vaginal childbirth contributes to approximately 85% of women experiencing some degree of trauma to the perineal region. Multiple factors play a role in the type and severity of trauma experienced, including parity, delivery method, and local practices. There is ongoing debate about best midwifery practice to reduce perineal trauma. Once perineal trauma has occurred, treatment also varies greatly, depending on its degree and severity, local practice and customs, and personal preference...
December 4, 2017: Cochrane Database of Systematic Reviews
Song Jing, Ren Dapeng, Yan Shiguo, Lan Jing, Yuan Xiao, Guo Qingyuan, Qi Xiangmin
OBJECTIVE: This study aimed to investigate the mechanism of cyclic stretch that promotesthe osteogenic differentiation of human periodontal ligament cells (hPDLCs) through the mediation of extracellular-signal-regulated kinase 1/2 (ERK1/2). METHODS: hPDLCs were isolated through the explant method and cultured in vitro. hPDLCs were mechanically stimulated by a multi-channel cell-stress-loading system for 1, 3, 6, 12, and 24 h. The magnitude of stretch was 10% deformation, and the frequency was 0...
October 1, 2017: Hua Xi Kou Qiang Yi Xue za Zhi, Huaxi Kouqiang Yixue Zazhi, West China Journal of Stomatology
Jing Zhao, Yuhei Nishimura, Akihiko Kimura, Kentaro Ozawa, Toshikazu Kondo, Toshio Tanaka, Masanori Yoshizumi
The pulsatile nature of blood flow exposes vascular smooth muscle cells (VSMCs) in the vessel wall to cyclic mechanical stretch (CMS), which evokes VSMC proliferation, cell death, phenotypic switching, and migration, leading to vascular remodeling. These responses have been observed in many cardiovascular diseases; however, the underlying mechanisms remain unclear. We have revealed that CMS of rat aortic smooth muscle cells (RASMCs) causes JNK- and p38-dependent cell death and that a calcium channel blocker and angiotensin II receptor antagonist decreased the phosphorylation of JNK and p38 and subsequently decreased cell death by CMS...
November 23, 2017: Scientific Reports
Arthur Leloup, Sofie De Moudt, Cor Van Hove, Paul Fransen
Large, elastic arteries buffer the pressure wave originating in the left ventricle and are constantly exposed to higher amplitudes of cyclic stretch (10%) than muscular arteries (2%). As a crucial factor for endothelial and smooth muscle cell function, cyclic stretch has, however, never been studied in ex vivo aortic segments of mice. To investigate the effects of cyclic stretch on vaso-reactivity of mouse aortic segments, we used the Rodent Oscillatory Tension Set-up to study Arterial Compliance (ROTSAC). The aortic segments were clamped at frequencies of 6-600 bpm between two variable preloads, thereby mimicking dilation as upon left ventricular systole and recoiling as during diastole...
2017: Frontiers in Physiology
Zhiwen Ding, Jie Yuan, Yanyan Liang, Jian Wu, Hui Gong, Yong Ye, Guoliang Jiang, Peipei Yin, Yang Li, Guoping Zhang, Chunjie Yang, Junjie Guo, Zhidan Chen, Xingxu Wang, Liqing Weng, Yunzeng Zou
Ryanodine receptor type 2 (RyR-2), the main Ca2+ release channel from sarcoplasmic reticulum in cardiomyocytes, plays a vital role in the regulation ofmyocardial contractile function and cardiac hypertrophy. However, the role of RyR-2 in cardiac fibrosis during the development of cardiac hypertrophy remains unclear.In this study, we examined whether RyR-2 regulates TGFβ1, which is secreted from cardiomyocytes and exerts on cardiac fibrosis using cultured cardiomyocytes and cardiac fibroblasts of neonatal rats...
December 12, 2017: International Heart Journal
Jakob Lorentzen, Maud Pradines, Jean-Michel Gracies, Jens Bo Nielsen
In this review, we will work around two simple definitions of two different entities, which most often co-exist in patients with lesions to central motor pathways: Spasticity is "Enhanced excitability of velocity-dependent responses to phasic stretch at rest", which will not be the subject of this review, while Spastic dystonia is tonic, chronic, involuntary muscle contraction in the absence of any stretch or any voluntary command (Gracies, 2005). Spastic dystonia is a much less well understood entity that will be the subject this review...
November 4, 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
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