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myogenic tone

Amanda I Rodriguez, Megan L A Thomas, Denis Fitzpatrick, Kristen L Janky
OBJECTIVES: Vestibular evoked myogenic potential (VEMP) testing is increasingly utilized in pediatric vestibular evaluations due to its diagnostic capability to identify otolith dysfunction and feasibility of testing. However, there is evidence demonstrating that the high-intensity stimulation level required to elicit a reliable VEMP response causes acoustic trauma in adults. Despite utility of VEMP testing in children, similar findings are unknown. It is hypothesized that increased sound exposure may exist in children because differences in ear-canal volume (ECV) compared with adults, and the effect of stimulus parameters (e...
March 2018: Ear and Hearing
Steven D Brooks, Stan Hileman, Paul D Chantler, Samantha Milde, Kent C Lemaster, Stephanie Frisbee, J Kevin Shoemaker, Dwayne N Jackson, Jefferson C Frisbee
The increasing prevalence and severity of clinical depression is strongly correlated with vascular disease risk, creating a comorbid condition with poor outcomes, although demonstrating a sexual disparity where females are at lower risk than males for subsequent cardiovascular events. To determine potential mechanisms responsible for this protection against stress/depression-induced vasculopathy in females, we exposed male and female ({plus minus}ovariectomy) rats to the unpredictable chronic mild stress (UCMS) model for 8 weeks and determined depressive symptom severity, vascular reactivity in aortic rings (AR) and ex vivo middle cerebral arteries (MCA), and determined the profile of major metabolites regulating vascular tone...
February 16, 2018: American Journal of Physiology. Heart and Circulatory Physiology
Éva Pál, Leila Hadjadj, Zoltán Fontányi, Anna Monori-Kiss, Zsuzsanna Mezei, Norbert Lippai, Attila Magyar, Andrea Heinzlmann, Gellért Karvaly, Emil Monos, György Nádasy, Zoltán Benyó, Szabolcs Várbíró
BACKGROUND AND PURPOSE: Vitamin D deficiency (VDD) is a global health problem, which can lead to several pathophysiological consequences including cardiovascular diseases. Its impact on the cerebrovascular system is not well understood. The goal of the present work was to examine the effects of VDD on the morphological, biomechanical and functional properties of cerebral arterioles. METHODS: Four-week-old male Wistar rats (n = 11 per group) were either fed with vitamin D deficient diet or received conventional rat chow with per os vitamin D supplementation...
2018: PloS One
Aravind Kumar Rajasekaran, Amey Rajan Savardekar, Nagaraja Rao Shivashankar
BACKGROUND: Schwannoma of the hypoglossal nerve is rare. This case report documents an atypical abnormality of the cervical vestibular evoked myogenic potential (cVEMP) in a patient with schwannoma of the hypoglossal nerve. The observed abnormality was attributed to the proximity of the hypoglossal nerve to the spinal accessory nerve in the medullary cistern and base of the skull. PURPOSE: To report cVEMP abnormality in a patient with hypoglossal nerve schwannoma and provide an anatomical correlation for this abnormality...
February 2018: Journal of the American Academy of Audiology
Bernard T Drumm, Benjamin E Rembetski, Caroline A Cobine, Salah A Baker, Gerard P Sergeant, Mark A Hollywood, Keith D Thornbury, Kenton M Sanders
Urethral smooth muscle cells (USMC) generate myogenic tone and contribute to urinary continence. Currently, little is known about Ca2+ signalling in USMC in situ, and therefore little is known about the source(s) of Ca2+ required for excitation-contraction coupling. We characterized Ca2+ signalling in USMC within intact urethral muscles using a genetically encoded Ca2+ sensor, GCaMP3, expressed selectively in USMC. USMC fired spontaneous intracellular Ca2+ waves that did not propagate cell-to-cell across muscle bundles...
January 31, 2018: Journal of Physiology
Xiaopeng Bai, Eikichi Ihara, Katsuya Hirano, Yoshimasa Tanaka, Kayoko Nakano, Satomi Kita, Takahiro Iwamoto, Haruei Ogino, Mayumi Hirano, Yoshinao Oda, Kazuhiko Nakamura, Yoshihiro Ogawa
Background and Aims: Hydrogen sulfide (H2S) is a major physiologic gastrotransmitter. Its role in the regulation of the lower esophageal sphincter (LES) function remains unknown. The present study addresses this question. Methods: Isometric contraction was monitored in circular smooth muscle strips of porcine LES. Changes in cytosolic Ca2+ concentration ([Ca2+]i) and force were simultaneously monitored in fura-2-loaded strips with front-surface fluorometry. The contribution of endogenous H2S to LES contractility was investigated by examining the effects of inhibitors of H2S-generating enzymes, including cystathionine-β-synthase, cystathionine-γ-lyase, and 3-mercaptopyruvate sulfurtransferase, on the LES function...
March 2018: Cellular and Molecular Gastroenterology and Hepatology
Prahalathan Pichavaram, Wen Yin, Kirk W Evanson, Jonathan H Jaggar, Salvatore Mancarella
Aims: Stromal interaction molecule 1 (STIM1) has emerged as an important player in the regulation of growth and proliferation of smooth muscle cells. Therefore, we hypothesized that STIM1 plays a crucial role in the maintenance of vascular integrity. The objective of this study was to evaluate whether reduced expression of STIM1 could modify the structure and function of the vasculature, leading to changes in blood pressure (BP). Methods and results: Smooth muscle-specific STIM1 knockout (sm-STIM1 KO) in mice resulted in arteries with ∼80% reduced STIM1 protein expression as compared to control mice...
January 19, 2018: Cardiovascular Research
Marisa Blanquet, Jens A Petersen, Antonella Palla, Dorothe Veraguth, Konrad P Weber, Dominik Straumann, Alexander A Tarnutzer, Hans H Jung
OBJECTIVE: We aimed to quantify peripheral-vestibular deficits that may contribute to imbalanced stance/gait in patients with inflammatory neuropathies. METHODS: Twenty-one patients (58 ± 15 y [mean age ± 1SD]; chronic-inflammatory-demyelinating-polyneuropathy = 10, Guillain-Barré Syndrome = 5, Anti-MAG peripheral neuropathy = 2, multifocal-motor-neuropathy = 4) were compared with 26 healthy controls. All subjects received video-head-impulse testing (vHIT), caloric irrigation and cervical/ocular vestibular-evoked myogenic-potentials (VEMPs)...
December 20, 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
Ioannis Kastanioudakis, Panagiotis Saravakos, Andreas Zigouris, Vasileios Ragos, Oliver Reichel, Nafsika Ziavra
OBJECTIVE: Cervical spondylosis and cervical disk herniation are the most frequent forms of degenerative disease in the cervical spine. Surgical treatment mainly includes anterior cervical disk fusion. However, information concerning vestibular-evoked myogenic potential (VEMP) recording in patients undergoing cervical spine surgery is limited. The present prospective study aimed to investigate the effect of anterior disk fusion surgery on cervical VEMP (cVEMP) parameters. MATERIALS AND METHODS: Twenty-five patients were enrolled in this study, and 20 patients (10 men and 10 women) completed cVEMP testing...
December 14, 2017: Journal of International Advanced Otology
Bo Zhang, Honglan Wang, Kai Jin, Ting Jiang, Shun Shen, Zimiao Luo, Yanyan Tuo, Xinguo Jiang, Xianping Liu, Yu Hu, Zhiqing Pang
Blood perfusion was always lower in tumor tissues as compared with that in surrounding normal tissues which lead to inadequate nanomedicine delivery to tumors. Inspired by the upregulation of both endothelin-1 (ET1) and its ETA receptor in tumor tissues and the crucial contribution of ET1-ETA receptor signaling to maintain myogenic tone of tumor vessels, we supposed that inhibition of ET1-ETA receptor signaling might selectively improve tumor perfusion and help deliver nanomedicine to tumors. Using human U87 MG glioblastomas with abundant vessels as the tumor model, immunofluorescence staining demonstrated that ETA receptor was overexpressed by in glioblastomas tissues compared with normal brain tissues...
December 21, 2017: Pharmacological Research: the Official Journal of the Italian Pharmacological Society
Masayo Koide, Arash Moshkforoush, Nikolaos M Tsoukias, David C Hill-Eubanks, George C Wellman, Mark T Nelson, Fabrice Dabertrand
Cerebral small vessel diseases (SVDs) encompass a group of genetic and sporadic pathological processes leading to brain lesions, cognitive decline, and stroke. There is no specific treatment for SVDs, which progress silently for years before becoming clinically symptomatic. Here, we examine parallels in the functional defects of parenchymal arterioles in CADASIL, a monogenic form of SVD, and in response to subarachnoid hemorrhage, a common type of hemorrhagic stroke that also targets the brain microvasculature...
December 15, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
Guus A de Waard, Christopher M Cook, Niels van Royen, Justin E Davies
For identification of myocardial ischaemia by non-invasive imaging or invasive physiological assessment, administration of a vasodilating or positive inotropic agent is often considered indispensable to exhaust the cardiac compensation mechanisms. Indeed, microcirculatory dilatation is needed for assessment of myocardial perfusion or coronary blood flow. However, three different modalities exist that quantify myocardial ischaemia without recourse to pharmacological stress agents, using either myocardial contrast echocardiography, imaging of myocardial blood volume or invasive coronary pressure measurement with the instantaneous wave-free ratio (iFR)...
December 11, 2017: European Heart Journal
Steven Li Fraine, Amanda Patel, Fabrice Duprat, Reza Sharif-Naeini
Mechanosensing is essential for several physiological functions including touch and pain sensations, osmoregulation, and controlling the myogenic tone of resistance arteries. Understanding how mechanosensitive ion channels (MSCs) are gated can provide important information regarding these processes. We have previously demonstrated that during pathological conditions such as polycystic kidney disease, polycystin 2 (TRPP2) inhibits the activity of potassium-selective MSCs through a filamin A-mediated cytoskeletal effect, and renders tubular epithelial cells susceptible to apoptosis...
December 12, 2017: Scientific Reports
Johan Holmberg, Anirban Bhattachariya, Azra Alajbegovic, Catarina Rippe, Mari Ekman, Diana Dahan, Tran Thi Hien, Thomas Boettger, Thomas Braun, Karl Swärd, Per Hellstrand, Sebastian Albinsson
OBJECTIVE: Pressure-induced myogenic tone is involved in autoregulation of local blood flow and confers protection against excessive pressure levels in small arteries and capillaries. Myogenic tone is dependent on smooth muscle microRNAs (miRNAs), but the identity of these miRNAs is unclear. Furthermore, the consequences of altered myogenic tone for hypertension-induced damage to small arteries are not well understood. APPROACH AND RESULTS: The importance of smooth muscle-enriched microRNAs, miR-143/145, for myogenic tone was evaluated in miR-143/145 knockout mice...
February 2018: Arteriosclerosis, Thrombosis, and Vascular Biology
Shannon M Dunn, Robert H Hilgers, Kumuda C Das
High-fat sucrose (HFS) diet in aged individuals causes severe weight gain (obesity) with much higher risk of cardiovascular diseases such as hypertension or atherosclerosis. Endothelial dysfunction is a major contributor for these vascular disorders. We hypothesize that prolonged ingestion of HFS diet by aged mice would accentuate endothelial dysfunction in the small resistance arteries. Male C57BL/6J mice at 12 weeks of age were divided into four groups and fed either normal chow (NC) or high-fat sucrose diet (HFS)...
December 2017: Physiological Reports
Peter Zu Eulenburg, Ria Maxine Ruehl, Pia Runge, Marianne Dieterich
Acoustic short tone bursts (STB) trigger ocular and cervical vestibular evoked myogenic potentials (oVEMPs/cVEMPs) by activating irregular otolith afferents. Simultaneously, STBs introduce an artificial net acceleration signal of otolith origin into the vestibular network. VEMP parameters as diagnostic otolith processing markers have been shown to decline after the age of thirty. To delineate the differential effects of healthy aging on the cortical vestibular subnetwork processing otolith information, we measured cVEMPs and the differential effects of unilateral STB in three age groups (20-40, 40-60, 60+; n=42) using functional neuroimaging...
October 23, 2017: European Journal of Neuroscience
Mária Szekeres, György L Nádasy, Eszter Soltész-Katona, László Hunyady
It was tested whether intrinsic CB1R activation modifies myogenic and agonist induced contraction of intramural coronary resistance arteries of the rat. CB1R protein was detected by immuno-histochemistry and by Western blot, its mRNA by qRT-PCR in their wall. Microsurgically prepared cylindrical coronary segments (∼100-150μm) developed myogenic contraction (∼20% of relaxed luminal diameter), from which a substantial relaxation (∼15%) in response to WIN55212 (a specific agonist of the CB1Rs) has been found...
October 16, 2017: Prostaglandins & Other Lipid Mediators
Yingying Zhou, Jia Fan, Huayuan Zhu, Li Ji, Wenyong Fan, Isha Kapoor, Yue Wang, Yuan Wang, Guoqing Zhu, Juejin Wang
Calcium influx from activated voltage-gated calcium channel CaV 1.2 in vascular smooth muscle cells is indispensable for maintaining myogenic tone and blood pressure. The function of CaV 1.2 channel can be optimized by alternative splicing, one of post-transcriptional modification mechanisms. The splicing factor Rbfox2 is known to regulate the CaV 1.2 pre-mRNA alternative splicing events during neuronal development. However, Rbfox2's roles in modulating the key function of vascular CaV 1.2 channel and in the pathogenesis of hypertension remain elusive...
December 2017: Hypertension
William F Jackson
Vascular smooth muscle cells (VSMCs) in resistance arteries and arterioles express a diverse array of voltage-gated K(+) (KV ) channels with members of the KV 1, KV 2 and KV 7 families being particularly important. Members of the KV channel family: 1.) are highly expressed in VSMCs; 2.) are active at the resting membrane potential of VSMCs in vivo (-45 to -30 mV); 3.) contribute to the negative feedback regulation of VSMC membrane potential and myogenic tone; 4.) are activated by cAMP-related vasodilators, hydrogen sulfide and hydrogen peroxide; 5...
October 6, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
Rebecca J St George, Victor S Gurfinkel, Jeff Kraakevik, John G Nutt, Fay B Horak
Upright stance in humans requires an intricate exchange between the neural mechanisms that control balance and those that control posture; however, the distinction between these control systems is hard to discern in healthy subjects. By studying balance and postural control of a participant with camptocormia - an involuntary flexion of the trunk during standing that resolves when supine - a divergence between balance and postural control was revealed. A kinematic and kinetic investigation of standing and walking showed a stereotyped flexion of the upper body by almost 80 degrees over a few minutes, and yet the participant's ability to control their center of mass within their base of support and to compensate for external perturbations remained intact...
October 4, 2017: Journal of Neurophysiology
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