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Arlene A Hirano, Xue Liu, Nicholas C Brecha, Steven Barnes
Genetic manipulation of horizontal cells using a Connexin57-iCre mouse (Cx57-iCre) line combined with calcium imaging is proving to be a valuable method to study horizontal cell feedback inhibition onto photoreceptor terminals. While it is accepted that horizontal cells provide lateral inhibitory feedback to photoreceptors, the cellular mechanisms that underlie this feedback inhibition remain only partially elucidated. Feedback inhibition of photoreceptors acts via modulation of their voltage-gated calcium channels at their synaptic terminal...
2018: Methods in Molecular Biology
Daisuke Shimaoka, Kenneth D Harris, Matteo Carandini
Changes in arousal modulate the activity of mouse sensory cortex, but studies in different mice and different sensory areas disagree on whether this modulation enhances or suppresses activity. We measured this modulation simultaneously in multiple cortical areas by imaging mice expressing voltage-sensitive fluorescent proteins (VSFP). VSFP imaging estimates local membrane potential across large portions of cortex. We used temporal filters to predict local potential from running speed or from pupil dilation, two measures of arousal...
March 20, 2018: Cell Reports
Germano Guerra, Angela Lucariello, Angelica Perna, Laura Botta, Antonio De Luca, Francesco Moccia
BACKGROUND: Neurovascular coupling (NVC) is the mechanism whereby an increase in neuronal activity (NA) leads to local elevation in cerebral blood flow (CBF) to match the metabolic requirements of firing neurons. Following synaptic activity, an increase in neuronal and/or astrocyte Ca2+ concentration leads to the synthesis of multiple vasoactive messengers. Curiously, the role of endothelial Ca2+ signaling in NVC has been rather neglected, although endothelial cells are known to control the vascular tone in a Ca2+ -dependent manner throughout peripheral vasculature...
March 21, 2018: International Journal of Molecular Sciences
Yimy Amarillo, Angela Isabel Tissone, German Mato, Marcela S Nadal
Slow repetitive burst firing by hyperpolarized thalamocortical (TC) neurons correlates with global slow rhythms (< 4 Hz), which are the physiological oscillations during N-REM sleep, or pathological ones during idiopathic epilepsy. The pacemaker activity of TC neurons depends on the expression of several subthreshold conductances, which are modulated in a behaviorally dependent manner. Here we show that up-regulation of the small and neglected inward rectifier potassium current IKir induces repetitive burst firing at slow and delta frequency bands...
March 21, 2018: Journal of Neurophysiology
Zi-Jian Wu, Jie Wang, Wen-Xiu Duan, Chang-Ping Gong, Ling Hu
OBJECTIVE: To observe the effect of electroacupuncture (EA) stimulation of Heart and Lung meridians on the expression of hyperpolarization-activated cyclic nucleotide gated potassium channel 2 (HCN 2) mRNA and protein in the myocar-dium of the left ventricle in acute myocardial ischemia (AMI) rats, so as to underlying its mechanism in improving ischemic myocardial injury. METHODS: A total of 120 male SD rats were randomly divided into normal control, model, EA-Heart Meridian (HT) and EA-Lung Meridian (LU) groups ( n =30 rats in each group)...
March 25, 2018: Zhen Ci Yan Jiu, Acupuncture Research
Jie Gao, Zhiqiang Hu, Liwei Shi, Na Li, Yeling Ouyang, Shaofang Shu, Shanglong Yao, Xiangdong Chen
It is widely accepted that the induction dose of anesthetics is higher in infants than in adults, although the relevant molecular mechanism remains elusive. We previously showed neuronal hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels contribute to hypnotic actions of propofol and ketamine. Interestingly, the expression of HCN channels in neocortex significantly changes during postnatal periods. Thus, we postulated that changes in HCN channels expression might contribute to sensitivity to intravenous anesthetics...
February 27, 2018: Oncotarget
Makoto Ando, Takayuki Matsumoto, Shota Kobayashi, Maika Iguchi, Kumiko Taguchi, Tsuneo Kobayashi
The purpose of this study was to determine the relationship of KCa channels to endothelium-dependent hyperpolarizing factor (EDHF)-mediated relaxation induced by acetylcholine (ACh) in the superior mesenteric arteries of 7-month-old spontaneously hypertensive rats (SHR). Upon inhibition of nitric oxide synthase and cyclooxygenase, ACh-induced EDHF-mediated relaxation was found to be weaker in SHR than in age-matched Wistar Kyoto rats (WKY). These relaxations in both group were attenuated by combined treatment with small-conductance and intermediate-conductance Ca2+-activated K+ channels (SKCa and IKCa) inhibitors, with the exception of relaxation resistant to inhibition of these channels in SHR (vs...
March 20, 2018: Canadian Journal of Physiology and Pharmacology
Larisa V Lysenko, Jeesun Kim, Francisco Madamba, Anna A Tyrtyshnaia, Aarti Ruparelia, Alexander M Kleschevnikov
Down syndrome (DS) is the most frequent genetic cause of developmental abnormalities leading to intellectual disability. One notable phenomenon affecting the formation of nascent neural circuits during late developmental periods is developmental switch of GABA action from depolarizing to hyperpolarizing mode. We examined properties of this switch in DS using primary cultures and acute hippocampal slices from Ts65Dn mice, a genetic model of DS. Cultures of DIV3-DIV13 Ts65Dn and control normosomic (2 N) neurons were loaded with FURA-2 AM, and GABA action was assessed using local applications...
March 14, 2018: Neurobiology of Disease
Paula K Bautista-Niño, Marien van der Stel, Wendy W Batenburg, René de Vries, Anton J M Roks, A H Jan Danser
Protein kinase G (PKG) Iα mediates the cyclic guanosine monophosphate-mediated vasodilatory effects induced by NO. Endothelium-derived hyperpolarizing factors (EDHFs), like H2 O2 can activate PKGIα in a cyclic guanosine monophosphate-independent manner, but whether this is true for all EDHFs (e.g., S-nitrosothiols) is unknown. Here, we investigated the contribution of PKGIα to bradykinin-, H2 O2 -, L-S-nitrosocysteine-, and light-induced relaxation in porcine coronary arteries, making use of the fact that thioredoxin reductase inhibition with auranofin or 1-chloro-2,4-dinitrobenzene potentiates PKGIα...
March 14, 2018: European Journal of Pharmacology
Sa Xiao, He Deng, Caohui Duan, Junshuai Xie, Huiting Zhang, Xianping Sun, Chaohui Ye, Xin Zhou
Dynamic hyperpolarized (HP)129 Xe MRI is able to visualize the process of lung ventilation, which potentially provides unique information about lung physiology and pathophysiology. However, the longitudinal magnetization of HP129 Xe is nonrenewable, making it difficult to achieve high image quality while maintaining high temporal-spatial resolution in the pulmonary dynamic MRI. In this paper, we propose a new accelerated dynamic HP129 Xe MRI scheme incorporating the low-rank, sparse and gas-inflow effects (L + S + G) constraints...
March 8, 2018: Journal of Magnetic Resonance
George J Lu, Arash Farhadi, Arnab Mukherjee, Mikhail G Shapiro
A long-standing goal of molecular imaging is to visualize cellular function within the context of living animals, necessitating the development of reporter genes compatible with deeply penetrant imaging modalities such as ultrasound and magnetic resonance imaging (MRI). Until recently, no reporter genes for ultrasound were available, and most genetically encoded reporters for MRI were limited by metal availability or relatively low sensitivity. Here we review how these limitations are being addressed by recently introduced reporter genes based on air-filled and water-transporting biomolecules...
March 14, 2018: Current Opinion in Chemical Biology
Charles E Norton, Steven S Segal
The sensory neurotransmitter calcitonin gene-related peptide (CGRP) is associated with vasodilation of systemic arteries through activation of ATP-sensitive potassium channels (KATP) in smooth muscle cells (SMCs), however its effects on endothelial cell (EC) membrane potential (Vm) are unresolved. In pulmonary arteries (PAs) of C57BL/6J mice, we questioned whether CGRP would hyperpolarize ECs as well as SMCs. Intact PAs were isolated and immunostained for CGRP to confirm sensory innervation; vessel segments (length, 1-2 mm; diameter ∼150 µm) with intact or denuded endothelium were cannulated and pressurized to 16 cm H2O at 37{degree sign}C...
March 15, 2018: American Journal of Physiology. Lung Cellular and Molecular Physiology
Bernd R Gardill, Ricardo E Rivera-Acevedo, Ching-Chieh Tung, Mark Okon, Lawrence P McIntosh, Filip Van Petegem
Voltage-gated sodium channels (NaV ) are responsible for the rapid depolarization of many excitable cells. They readily inactivate, a process where currents diminish after milliseconds of channel opening. They are also targets for a multitude of disease-causing mutations, many of which have been shown to affect inactivation. A cluster of disease mutations, linked to Long-QT and Brugada syndromes, is located in a C-terminal EF-hand like domain of NaV 1.5, the predominant cardiac sodium channel isoform. Previous studies have suggested interactions with the III-IV linker, a cytosolic element directly involved in inactivation...
March 14, 2018: Scientific Reports
Junu Bae, Zijian Zhou, Thomas Theis, Warren S Warren, Qiu Wang
Hyperpolarized magnetic resonance (HP-MR) is a powerful, sensitive, and noninvasive approach to visualize molecular structure, function, and dynamics in vitro and in vivo. Current applications of HP-MR mostly rely on hyperpolarization of target compounds in dedicated hyperpolarizers because biomolecules can typically not be hyperpolarized directly in vivo. The injected hyperpolarized probes often undergo multiple metabolic pathways in living systems, and it remains challenging to localize and identify specific targets with high chemical selectivity...
March 2018: Science Advances
Or Szekely, Gregory Lars Olsen, Isabella Caterina Felli, Lucio Frydman
This study demonstrates the usefulness derived from relying on hyperpolarized water obtained by dissolution DNP, for site-resolved biophysical NMR studies of intrinsically disordered proteins. Thanks to the facile amide-solvent exchange experienced by protons in these proteins, 2D NMR experiments that like HMQC rely on the polarization of the amide protons, can be enhanced using hyperpolarized water by several orders of magnitude over their conventional counterparts. Optimizations of the DNP procedure and of the subsequent injection into the protein sample are necessary to achieve these gains while preserving state-of-the-art resolution; procedures enabling this transfer of the hyperpolarized water and the achievement of foamless hyperpolarized protein solutions, are here demonstrated...
March 12, 2018: Analytical Chemistry
Shota Hodono, Akihiro Shimokawa, Neil J Stewart, Yukiko Yamauchi, Renya Nishimori, Mami Yamane, Hirohiko Imai, Hideaki Fujiwara, Atsuomi Kimura
PURPOSE: High Mobility Group Box1 (HMGB1), which is one of the damage-associated molecular pattern molecules relating to various inflammatory diseases, has gained interest as a therapeutic target because of its involvement in wound healing processes. In the present study, we investigated HMGB1 as a potential therapeutic target in a model of lung fibrosis using a preclinical hyperpolarized129 Xe (HPXe) MRI system. METHODS: Lung injury was induced by intra-peritoneal injection of bleomycin (BLM) in 19 mice...
March 9, 2018: Magnetic Resonance in Medical Sciences: MRMS
Zhongjian Cheng, Xinggui Shen, Xiaohua Jiang, Huimin Shan, Maria Cimini, Pu Fang, Yong Ji, Joon Young Park, Konstantinos Drosatos, Xiaofeng Yang, Christopher G Kevil, Raj Kishore, Hong Wang
Insufficient hydrogen sulfide (H2 S) has been implicated in Type 2 diabetic mellitus (T2DM) and hyperhomocysteinemia (HHcy)-related cardiovascular complications. We investigated the role of H2 S in T2DM and HHcy-induced endothelial dysfunction in small mesenteric artery (SMA) of db/db mice fed a high methionine (HM) diet. HM diet (8 weeks) induced HHcy in both T2DM db/db mice and non-diabetic db/+ mice (total plasma Hcy: 48.4 and 31.3 µM, respectively), and aggravated the impaired endothelium-derived hyperpolarization factor (EDHF)-induced endothelium-dependent relaxation to acetylcholine (ACh), determined by the presence of eNOS inhibitor N(ω)-nitro-L-arginine methyl ester (L-NAME) and prostacyclin (PGI2 ) inhibitor indomethacin (INDO), in SMA from db/db mice but not that from db/+ mice...
February 14, 2018: Redox Biology
Ipsita Mohanty, Subas Chandra Parija, Sujit Suklabaidya, Satish Rattan
Extracellular pH is an important physiological determinant of vascular tone that is normally maintained within 7.35-7.45. Any change outside this range leads to severe pathological repercussions. We investigated the unknown effects of extracellular acidosis on relaxation in the superior mesenteric artery (SMA) of goat. SMA rings were employed to maintain isometric contractions at extracellular pH (pHo ) 7.4 and 6.8. We analyzed the effect of acidosis (pHo 6.8) compared to physiological pH (pHo 7.4) on three signaling mediators of endothelium-dependent hyperpolarization: nitric oxide (NO), prostaglandin I2 (PGI2 ), and myoendothelial gap junctions (MEGJ)...
March 7, 2018: European Journal of Pharmacology
Rasmus Stilling Tougaard, Esben Søvsø Szocska Hansen, Christoffer Laustsen, Jakob Lindhardt, Marie Schroeder, Hans Erik Bøtker, Won Yong Kim, Henrik Wiggers, Hans Stødkilde-Jørgensen
PURPOSE: Deranged metabolism is now recognized as a key causal factor in a variety of heart diseases, and is being studied extensively. However, invasive methods may alter metabolism, and conventional imaging techniques measure tracer uptake but not downstream metabolism. These challenges may be overcome by hyperpolarized MR, a noninvasive technique currently crossing the threshold into human trials. The aim of this study was to image metabolic changes in the heart in response to endogastric glucose bolus and to acute hypertension...
March 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Timo Gutermuth, Sarah Herbell, Roman Lassig, Mikael Brosché, Tina Romeis, José Alberto Feijó, Rainer Hedrich, Kai Robert Konrad
Pollen tubes (PTs) are characterized by having tip-focused cytosolic calcium ion (Ca2+ ) concentration ([Ca2+ ]cyt ) gradients, which are believed to control PT growth. However, the mechanisms by which the apical [Ca2+ ]cyt orchestrates PT growth are not well understood. Here, we aimed to identify these mechanisms by combining reverse genetics, cell biology, electrophysiology, and live-cell Ca2+ and anion imaging. We triggered Ca2+ -channel activation by applying hyperpolarizing voltage pulses and observed that the evoked [Ca2+ ]cyt increases were paralleled by high anion channel activity and a decrease in the cytosolic anion concentration at the PT tip...
March 9, 2018: New Phytologist
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