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myogenic tone

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https://www.readbyqxmd.com/read/28720714/maxi-k-channel-bkca-activity-veils-the-myogenic-tone-of-mesenteric-artery-in-rats
#1
Eun Yeong Suh, Ming Zhe Yin, Haiyue Lin, Yin Hua Zhang, Hae Young Yoo, Sung Joon Kim
Arterioles and small arteries change their tone in response to transmural pressure changes, called myogenic tone (MT). In comparison to the branches of cerebral arteries (CA) showing prominent MT, the third branches of mesenteric arteries (MA) with similar diameters show weaker MT Here, we aimed to analyze the electrophysiological differences responsible for the weaker MT in MA (MTMA) than MT in CA (MTCA). We measured ionic current using patch clamp in isolated MA smooth muscle cells (MASMCs) and CA smooth muscle cells (CASMCs) of rats...
July 2017: Physiological Reports
https://www.readbyqxmd.com/read/28719825/degeneration-of-the-vestibular-nerve-in-unilateral-meniere-s-disease-evaluated-by-galvanic-vestibular-evoked-myogenic-potentials
#2
Chih-Ming Chang, Yi-Ho Young, Fu-Shan Jaw, Chi-Te Wang, Po-Wen Cheng
OBJECTIVE: The staging system of Meniere's disease utilizes audiograms to probe cochlear dysfunction. We explored the addition of galvanic vestibular-evoked myogenic potentials (VEMP) to further explore vestibular function. METHODS: Seventy patients with unilateral Meniere's disease were enrolled in this study. Within 2weeks of diagnosis, all subjects underwent pure tone audiometry, cervical and ocular VEMP, and caloric test. The prevalence of abnormal tests and the VEMP characteristic parameters such as latencies and amplitudes were analyzed...
June 19, 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28684629/genetic-deletion-of-nadph-oxidase-1-rescues-microvascular-function-in-mice-with-metabolic-disease
#3
Jennifer A Thompson, Sebastian Larion, James D Mintz, Eric J Belin de Chantemele, David J Fulton, David W Stepp
Rationale: Early vascular changes in metabolic disease that precipitate the development of cardiovascular complications are largely driven by reactive oxygen species (ROS) accumulation, yet the extent to which excess ROS derive from specific Nox isoforms remains ill-defined. Objective: Identify the role of Nox1 in the development of microvascular dysfunction in metabolic disease. Methods and Results: Four genotypes were generated by breeding Nox1 knock-out (KO) mice with db/db mice: lean (HdbWnox1); lean Nox1 KO (HdbKnox1); obese (KdbWnox1); obese KK (KdbKnox1)...
July 6, 2017: Circulation Research
https://www.readbyqxmd.com/read/28667050/regional-heterogeneity-in-the-mechanisms-of-myogenic-tone-in-hamster-arterioles
#4
William F Jackson, Erika M Boerman
Myogenic tone is an important feature of arterioles and resistance arteries, but the mechanisms responsible for this hallmark characteristic remain unclear. We utilized pharmacological inhibitors to compare the roles played by phospholipase C (PLC; 10 μM U73122), inositol 1,4,5 trisphosphate receptors (IP3R; 100 μM 2-Aminoethoxydiphenylborane, 2-APB), protein kinase C (PKC; 10μM Bisindolylmaleimide I), angiotensin II type 1 receptors (AT1R; 1μM losartan), Rho-kinase (10nM-30μM Y27632 or 300nM H1152), stretch-activated ion channels (10nM-1μM Gd(3+) or 5μM spider venom toxin GsMTx-4) and L-type voltage-gated Ca(2+) channels (0...
June 30, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28665172/treatment-with-low-dose-fasudil-for-acute-ischemic-stroke-in-chronic-hypertension
#5
Siu-Lung Chan, Marilyn J Cipolla
We investigated the effect of Rho kinase inhibition on changes in cerebral blood flow (CBF), brain injury and vascular function after ischemic stroke in spontaneously hypertensive rats (SHR). Changes in core MCA and collateral perfusion were measured by a validated laser Doppler method. Animals underwent 2 h tMCAO and 2 h reperfusion. Fasudil (0.1 mg/kg, i.v.) or vehicle was given at 30 min ischemia (n = 9/group; mean (SD)). Brain injury was determined by 2,3,5-triphenyltetrazolium chloride staining...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28652517/role-of-prostatic-interstitial-cells-in-prostate-motility
#6
Richard J Lang, Hikaru Hashitani
The prostate is a gland whose secretions contribute to the seminal fluids ejaculated upon activation of autonomic sympathetic nerves. In elder males, the prostate undergoes an increase in stroma mass and myogenic tone, leading to benign prostatic hyperplasia that occludes the proximal urethra and the presentation of various lower urinary tract symptoms that decrease their quality of life. This review summarises the role of prostatic interstitial cells (PICs) in the generation of the spontaneous tone in the prostate...
2017: Journal of Smooth Muscle Research, Nihon Heikatsukin Gakkai Kikanshi
https://www.readbyqxmd.com/read/28641325/superior-canal-dehiscence-syndrome-associated-with-scuba-diving
#7
Naoharu Kitajima, Akemi Sugita-Kitajima, Seiji Kitajima
A 28-year-old female diver presented with dizziness and difficulty clearing her left ear whilst scuba diving. Her pure-tone audiometry and tympanometry were normal. Testing of Eustachian tube function revealed tubal stenosis. Video-oculography revealed a predominantly torsional nystagmus while the patient was in the lordotic position. Fistula signs were positive. High-resolution computed tomography (HRCT) of the temporal bone revealed a diagnosis of bilateral superior semicircular canal dehiscence (SCDS). Cervical vestibular-evoked myogenic potential (cVEMP) testing showed that the amplitude of the cVEMP measured from her left ear was larger than that from the right...
June 2017: Diving and Hyperbaric Medicine: the Journal of the South Pacific Underwater Medicine Society
https://www.readbyqxmd.com/read/28603637/t-type-voltage-gated-ca-2-channels-do-not-contribute-to-the-negative-feedback-regulation-of-myogenic-tone-in-murine-superior-epigastric-arteries
#8
Brendan Mullan, Jessica Pettis, William F Jackson
T-type voltage-gated Ca(2+) channels (CaV3.2 VGCC) have been hypothesized to control spontaneous transient outward currents (STOCs) through large-conductance Ca(2+)-activated K(+) channels (BKCa), and contribute to the negative-feedback regulation of myogenic tone. We tested this hypothesis in superior epigastric arteries (SEAs) isolated from male C57BL/6 mice. SEAs were isolated and enzymatically dissociated to obtain single smooth muscle cells (SMCs) for whole-cell recording of paxilline-sensitive (PAX, 1 μmol/L) STOCs at -30 mV, or cannulated and studied by pressure myography (80 cm H2O, 37°C)...
June 2017: Pharmacology Research & Perspectives
https://www.readbyqxmd.com/read/28533763/is-alteration-of-tuning-property-in-cervical-vestibular-evoked-myogenic-potential-specific-for-m%C3%A3-ni%C3%A3-re-s-disease
#9
Toshihisa Murofushi, Masahito Tsubota, Ryota Suizu, Eriko Yoshimura
OBJECTIVE: The aim of this study is to show sensitivity and specificity of cervical vestibular-evoked myogenic potential (cVEMP) tuning property test to Ménière's disease (MD) in comparison with healthy controls (HC) and patients with other vestibular diseases. SUBJECTS: Totally 92 subjects (50 women and 42 men, 20-77 years of age) were enrolled in this study. Subjects were composed of 38 definite unilateral MD patients, 11 unilateral benign paroxysmal positional vertigo patients, 14 vestibular migraine patients, 19 unilateral vestibular neuritis patients, and 10 HC...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28520834/effect-of-electrode-montage-and-head-position-on-air-conducted-ocular-vestibular-evoked-myogenic-potential
#10
Kathryn Makowiec, Devin L McCaslin, Gary P Jacobson, Kelsey Hatton, John Lee
Purpose: The purpose of this investigation was to identify the optimal recording parameters for evoking the ocular vestibular evoked myogenic potential (oVEMP) using air-conduction stimuli. Method: Subjects were 17 otologically and neurologically intact adults (age: M = 24.18 years, SD = 1.91 years). The oVEMP responses were elicited using a 500-Hz tone burst air-conduction stimulus presented at an intensity of 95 dB nHL. The setting was a balance function laboratory that was part of a large tertiary care otology clinic...
June 13, 2017: American Journal of Audiology
https://www.readbyqxmd.com/read/28484390/spatiotemporal-mapping-techniques-show-clozapine-impairs-neurogenic-and-myogenic-patterns-of-activity-in-the-colon-of-the-rabbit-in-a-dose-dependent-manner
#11
Susanna Every-Palmer, Roger G Lentle, Gordon Reynolds, Corrin Hulls, Paul Chambers, Helen Dunn, Pete M Ellis
Background: Clozapine, an antipsychotic used in treatment-resistant schizophrenia, has adverse gastrointestinal effects with significant associated morbidity and mortality. However, its effects on defined patterns of colonic contractile activity have not been assessed. Method: We used novel radial and longitudinal spatiotemporal mapping techniques, combined with and monitoring of ambient lumen pressure, in ex vivo preparations of triply and of singly haustrated portions of rabbit colon. We identified the contractile patterns of mass peristalses, fast phasic, and ripple contractions and directly qualified the effects of clozapine, at concentrations of 10 μmol/L, 20 μmol/L, and 30 μmol/L, and of norclozapine, the main metabolite of clozapine, on contractile patterns...
2017: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/28475214/the-angiotensin-ii-receptor-type-1b-is-the-primary-sensor-of-intraluminal-pressure-in-cerebral-artery-smooth-muscle-cells
#12
Paulo W Pires, Eun-A Ko, Harry A T Pritchard, Michael Rudokas, Evan Yamasaki, Scott Earley
The angiotensin II receptor type 1b (AT1 Rb ) is the primary sensor of intraluminal pressure in cerebral arteries. Pressure or membrane-stretch induced stimulation of AT1 Rb activates the TRPM4 channel and results in inward transient cation currents that depolarize smooth muscle cells, leading to vasoconstriction. Activation of either AT1 Ra or AT1 Rb with angiotensin II stimulates TRPM4 currents in cerebral artery myocytes and vasoconstriction of cerebral arteries. The expression of AT1 Rb mRNA is ∼30-fold higher than AT1 Ra in whole cerebral arteries and ∼45-fold higher in isolated cerebral artery smooth muscle cells...
July 15, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28472069/detection-of-trpv4-channel-current-like-activity-in-fawn-hooded-hypertensive-fhh-rat-cerebral-arterial-muscle-cells
#13
Debebe Gebremedhin, David X Zhang, Dorothee Weihrauch, Nnamdi N Uche, David R Harder
The transient receptor potential vallinoid type 4 (TRPV4) is a calcium entry channel known to modulate vascular function by mediating endothelium-dependent vasodilation. The present study investigated if isolated cerebral arterial myocytes of the Fawn Hooded hypertensive (FHH) rat, known to display exaggerated KCa channel current activity and impaired myogenic tone, express TRPV4 channels at the transcript and protein level and exhibit TRPV4-like single-channel cationic current activity. Reverse transcription polymerase chain reaction (RT-PCR), Western blot, and immunostaining analysis detected the expression of mRNA transcript and translated protein of TRPV4 channel in FHH rat cerebral arterial myocytes...
2017: PloS One
https://www.readbyqxmd.com/read/28436247/effects-of-peripheral-vestibular-dysfunction-on-dynamic-postural-stability-measured-by-the-functional-reach-test-and-timed-up-and-go-test
#14
Toshiko Nishi, Teru Kamogashira, Chisato Fujimoto, Makoto Kinoshita, Naoya Egami, Keiko Sugasawa, Tatsuya Yamasoba, Shinichi Iwasaki
OBJECTIVE: To investigate the influence of vestibular function on dynamic postural stability assessed by the functional reach test (FRT) and the timed up and go test (TUG). STUDY DESIGN: Retrospective study. SETTING: Tertiary referral center. SUBJECTS AND METHODS: The FRT and TUG were performed in 399 patients with dizziness. The effects of peripheral vestibular dysfunction assessed by the caloric test and cervical vestibular evoked myogenic potentials (cVEMPs) to air-conducted sound (500 Hz, tone burst) on the results of FRT and TUG were analyzed...
June 2017: Annals of Otology, Rhinology, and Laryngology
https://www.readbyqxmd.com/read/28435971/-mechanisms-underlying-rat-coronary-arterial-vasoconstriction-induced-by-blockade-of-inward-rectifier-potassium-channels-with-bacl2
#15
Fang-Wen Fan, Ze-Fang He, Meng Shi, Rong Yang, Xiao-Min Hou, Yu Liu, Ming-Sheng Zhang
In order to explore the mechanisms underlying the vasoconstriction induced by blockade of inward rectifier K(+) channels (Kir) with BaCl2, myogenic tone of isolated rat coronary artery (RCA) was recorded with wire myograph. The dependence of BaCl2- induced contraction on intracellular Ca(2+) ([Ca(2+)]i) release and extracellular Ca(2+) ([Ca(2+)]o) influx was studied by Ca(2+) deprivation and restoration. The mechanisms underlying BaCl2-induced RCA contraction were investigated with specific inhibitors. BaCl2 (0...
April 25, 2017: Sheng Li Xue Bao: [Acta Physiologica Sinica]
https://www.readbyqxmd.com/read/28432059/increased-amplitude-of-inward-rectifier-k-currents-with-advanced-age-in-smooth-muscle-cells-of-murine-superior-epigastric-arteries
#16
Sebastien Hayoz, Jessica Pettis, Vanessa Bradley, Steven S Segal, William F Jackson
Inward rectifier K(+) channels (KIR) may contribute to skeletal muscle blood flow regulation and adapt to advanced age. Using mouse abdominal wall superior epigastric arteries (SEAs) from either young (3-6 months) or old (24-26 months) male C57BL/6 mice, we investigated whether SEA smooth muscle cells (SMCs) express functional KIR, and how aging may affect KIR function. Freshly dissected SEAs were either enzymatically dissociated to isolate SMCs for electrophysiological recording (perforated patch) and mRNA expression, or used intact for pressure myography...
April 21, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28419063/the-effect-of-elevated-intracranial-pressure-on-frequency-tuning-of-air-conducted-ocular-vestibular-myogenic-potentials-in-m%C3%A3-ni%C3%A3-re-s-disease-patients
#17
Rebecca Maxwell, Claudia Jerin, Robert Gürkov
OBJECTIVE: To investigate the effect of increased intracranial pressure on ocular vestibular-evoked myogenic potential (oVEMP) amplitudes and frequency tuning in patients with Ménière's disease (MD) to elucidate whether oVEMPS recorded under such conditions could provide a simple and accurate diagnostic test for MD. SETTING: Tertiary referral center for otology and neurotology. PATIENTS: Ten patients with certain unilateral MD (mean age = 48...
July 2017: Otology & Neurotology
https://www.readbyqxmd.com/read/28396535/pregnancy-reprograms-large-conductance-ca-2-activated-k-channel-in-uterine-arteries-roles-of-ten-eleven-translocation-methylcytosine-dioxygenase-1-mediated-active-demethylation
#18
Xiang-Qun Hu, Chiranjib Dasgupta, Man Chen, Daliao Xiao, Xiaohui Huang, Limin Han, Shumei Yang, Zhice Xu, Lubo Zhang
The large-conductance Ca(2+)-activated K(+) (BKCa) channel is of critical importance in pregnancy-mediated increase in uterine artery vasodilation and blood flow. The present study tested the hypothesis that active DNA demethylation plays a key role in pregnancy-induced reprogramming and upregulation of BKCa channel β1 subunit (BKβ1) in uterine arteries. Uterine arteries were isolated from nonpregnant and near-term pregnant sheep. Pregnancy significantly increased the expression of ten-eleven translocation methylcytosine dioxygenase 1 (TET1) in uterine arteries...
June 2017: Hypertension
https://www.readbyqxmd.com/read/28378814/constitutive-smooth-muscle-tumour-necrosis-factor-regulates-microvascular-myogenic-responsiveness-and-systemic-blood-pressure
#19
Jeffrey T Kroetsch, Andrew S Levy, Hangjun Zhang, Roozbeh Aschar-Sobbi, Darcy Lidington, Stefan Offermanns, Sergei A Nedospasov, Peter H Backx, Scott P Heximer, Steffen-Sebastian Bolz
Tumour necrosis factor (TNF) is a ubiquitously expressed cytokine with functions beyond the immune system. In several diseases, the induction of TNF expression in resistance artery smooth muscle cells enhances microvascular myogenic vasoconstriction and perturbs blood flow. This pathological role prompted our hypothesis that constitutively expressed TNF regulates myogenic signalling and systemic haemodynamics under non-pathological settings. Here we show that acutely deleting the TNF gene in smooth muscle cells or pharmacologically scavenging TNF with etanercept (ETN) reduces blood pressure and resistance artery myogenic responsiveness; the latter effect is conserved across five species, including humans...
April 5, 2017: Nature Communications
https://www.readbyqxmd.com/read/28370794/short-term-48-hours-intravenous-serelaxin-infusion-has-no-effect-on-myogenic-tone-or-vascular-remodeling-in-rat-mesenteric-arteries
#20
Maria Jelinic, Chen Huei Leo, Sarah A Marshall, Sevvandi N Senadheera, Laura J Parry, Marianne Tare
BACKGROUND: Short-term intravenous serelaxin (recombinant human relaxin-2) infusion enhances endothelium-dependent relaxation in mesenteric arteries. This is initially underpinned by increased nitric oxide (NO) followed by a transition to prostacyclin. The effects of short-term intravenous serelaxin treatment on pressure-induced myogenic tone and vascular remodeling in these arteries are unknown. Therefore, we investigated the effects of serelaxin infusion on pressure-induced myogenic tone and passive mechanical wall properties in mesenteric arteries...
March 31, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
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