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Microcirculation: the Official Journal of the Microcirculatory Society, Inc

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https://www.readbyqxmd.com/read/29239491/regulation-of-microvascular-function-by-voltage-gated-potassium-channels-new-tricks-for-an-ancient-dog
#1
Matthew A Nystoriak, Manuel F Navedo
Arterial tone is tightly regulated by a variety of potassium (K+ ) permeable ion channels at the sarcolemma of vascular smooth muscle cells. In particular, several types of voltage-gated K+ (KV ) channels provide a significant hyperpolarizing influence and serve to oppose pressure and agonist-induced membrane depolarization to promote smooth muscle relaxation and augmentation of vascular diameter and blood flow. In recent years, a number of studies have underscored previously unknown roles for particular KV subunits, new modes of channel regulation, and distinct cellular functions for these channels during physiological and pathological conditions...
December 14, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29211322/perivascular-adipose-tissue-and-the-dynamic-regulation-of-kv-7-and-kir-channels-implications-to-resistant-hypertension
#2
Maik Gollasch, Donald G Welsh, Rudolf Schubert
Resistant hypertension is defined as high blood pressure that remains uncontrolled despite treatment with at least three antihypertensive drugs at adequate doses. Resistant hypertension is an increasingly common clinical problem in older age, obesity, diabetes, sleep apnea, and chronic kidney disease. Although the direct vasodilator minoxidil was introduced in the early 1970s, only recently has this drug been shown to be particularly effective in a subgroup of patients with treatment-resistant or uncontrolled hypertension...
December 6, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29210138/endovascular-shedding-markers-in-patients-with-heart-failure-with-reduced-ejection-fraction
#3
Petra Nijst, Jirka Cops, Pieter Martens, Quirine Swennen, Matthias Dupont, W H Wilson Tang, Wilfried Mullens
BACKGROUND: Endothelial glycocalyx degradation has been associated with multiple pathophysiological processes in cardiovascular disease. AIMS: To explore the role of glycocalyx shedding markers in pathophysiology of heart failure with reduced ejection fraction (HFrEF). METHODS: In 123 HFrEF patients the concentration, prognostic value and association of glycocalyx shedding markers with other disease processes was investigated. RESULTS: Median hyaluronic acid (HA) levels and syndecan-1 levels in HFrEF patients were respectively 29...
December 6, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29210137/hyperoxia-does-not-affect-oxygen-delivery-in-healthy-volunteers-while-causing-a-decrease-in-sublingual-perfusion
#4
B Smit, Y M Smulders, E C Eringa, H P M M Gelissen, A R J Girbes, H J S de Grooth, H H M Schotman, P G Scheffer, H M Oudemans-van Straaten, A M E Spoelstra-de Man
To determine the human dose-response relationship between a stepwise increase in arterial oxygen tension and its associated changes in oxygen delivery and sublingual microcirculatory perfusion METHODS: Fifteen healthy volunteers breathed increasing oxygen fractions for 10 minutes to reach arterial oxygen tensions of baseline (breathing air), 20 kPa, 40 kPa, 60 kPa and max kPa (breathing oxygen). Systemic hemodynamics were measured continuously by the volume-clamp method. At the end of each period, the sublingual microcirculation was assessed by Sidestream Darkfield Imaging RESULTS: Systemic oxygen delivery was unchanged throughout the study (Pslope =0...
December 6, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29161755/kv-1-channel-expression-and-vasomotor-function-in-human-coronary-resistance-arteries
#5
Yoshinori Nishijima, Ankush Korishettar, Dawid S Chabowski, Sheng Cao, Xiaodong Zheng, David D Gutterman, David X Zhang
OBJECTIVES: KV channels are important regulators of vascular tone, but the identity of specific KV channels involved and their regulation in disease remain less well understood. We determined the expression of KV 1 channel subunits and their role in cAMP-mediated dilation in coronary resistance arteries from subjects with and without coronary artery disease (CAD). METHODS: Human coronary arteries and arterioles (HCA) from non-CAD and CAD patients were assessed for mRNA and protein expression of KV 1 channel subunits with molecular techniques and for vasodilator response with isolated arterial myography...
November 21, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29130567/treatment-strategies-in-coronary-microvascular-dysfunction-a-systematic-review-of-interventional-studies
#6
Hannah E Suhrs, Marie M Michelsen, Eva Prescott
Coronary microvascular dysfunction has been associated with a wide spectrum of diseases and conditions, and it has proven to be a strong prognostic marker of morbidity and mortality. Despite increased attention guideline-based treatment recommendations are lacking. We performed a systematic review of pharmacological and non-pharmacological interventions to improve coronary perfusion, assessed by intracoronary Doppler, transthoracic Doppler echocardiography, positron emission tomography, cardiac magnetic resonance imaging, transthoracic contrast perfusion echocardiography and dilution techniques...
November 11, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29117630/biophysical-properties-of-microvascular-endothelium-requirements-for-initiating-and-conducting-electrical-signals
#7
Adam Kapela, Erik J Behringer, Steven S Segal, Nikolaos M Tsoukias
OBJECTIVE: Electrical signaling along the endothelium underlies spreading vasodilation and blood flow control. We use mathematical modeling to determine the electrical properties of the endothelium and gain insight into the biophysical determinants of electrical conduction. METHODS: Electrical conduction data along endothelial cell (EC) tubes (40 μm wide, 2.5 mm long) isolated from mouse skeletal muscle resistance arteries were analyzed using cable equations and a multicellular computational model...
November 8, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29110409/coronary-microvascular-kv1-channels-as-regulatory-sensors-of-intracellular-pyridine-nucleotide-redox-potential
#8
Marc M Dwenger, Vahagn Ohanyan, Manuel F Navedo, Matthew A Nystoriak
Smooth muscle voltage-gated potassium (Kv) channels are important regulators of microvascular tone and tissue perfusion. Recent studies indicate that Kv1 channels represent a key component of the physiological coupling between coronary blood flow and myocardial oxygen demand. While the mechanisms by which metabolic changes in the heart are transduced to alter coronary Kv1 channel gating and promote vasodilation are unclear, a growing body of evidence underscores a pivotal role of Kv1 channels in sensing the cellular redox status...
November 7, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29110368/kv-channels-and-vascular-smooth-muscle-cells-proliferation
#9
José R López-López, Pilar Cidad, M Teresa Pérez-García
Kv channels are present in virtually all vascular smooth muscle cells (VSMC) and strongly influence contractile responses. However, they are also instrumental in the proliferative, migratory and secretory functions of synthetic, dedifferentiated VSMCs cells upon phenotypic modulation (PM). In fact, Kv channels not only contribute to all these processes but they are also active players in the phenotypic switch itself. This review is focused on the role(s) of Kv channels in VSMC proliferation, which is one of the best characterized functions of dedifferentiated VSMCs...
November 7, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29106775/oxygen-delivery-from-the-cerebral-microvasculature-to-tissue-is-governed-by-a-single-time-constant-of-approximately-6-seconds
#10
S J Payne, C Lucas
The cerebral microvasculature plays a key role in the coupling between cerebral blood flow and metabolism. Although experimental imaging techniques now allow for finely detailed measurements of flow and oxygenation, within humans measurements remain confined to a voxel level scale, of order 1 mm. Mathematical models are thus key in interpreting such data. However, these can be highly complicated, due to the large number of vessels and the non-linearities in the governing equations. We thus propose here a new model of the cerebral microvasculature and show how its behaviour can be simplified based on order of magnitude arguments...
November 6, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29072364/molecular-determinants-of-beta-adrenergic-signaling-to-voltage-gated-k-channels-in-the-cerebral-circulation
#11
Sung W Rhee, Nancy J Rusch
Voltage-gated K(+) (Kv ) channels are major determinants of membrane potential in vascular smooth muscle cells (VSMCs), and regulate the diameter of small cerebral arteries and arterioles. However, the intracellular structures that govern the expression and function of vascular Kv channels are poorly understood. Scaffolding proteins including postsynaptic density 95 (PSD95) recently were identified in rat cerebral VSMCs. Primarily characterized in neurons, the PSD95 scaffold has more than 50 known binding partners and it can mediate macromolecular signaling between cell surface receptors and ion channels...
October 26, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29047195/hepatic-transudation-barrier-properties
#12
R M Dongaonkar, R H Stewart, C M Quick, K L Uray, C S Cox, G A Laine
OBJECTIVE: Fluid and protein continuously transudes from the surface of the liver. Despite a common understanding that transudation plays a critical role in hepatic interstitial and peritoneal fluid balance, transudation from the entire liver has not been studied. Therefore, the goal of the present work was to provide the first direct measurement of the hepatic transudation rate and transudation barrier properties. METHODS: Transudation rates were determined by collecting transudate from the entire liver...
October 19, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29044853/regulation-of-voltage-gated-potassium-channels-in-vascular-smooth-muscle-during-hypertension-and-metabolic-disorders
#13
Madeline Nieves-Cintrón, Arsalan U Syed, Matthew A Nystoriak, Manuel F Navedo
Voltage-gated potassium (KV ) channels are key regulators of vascular smooth muscle contractility and vascular tone, and thus have major influence on the microcirculation. KV channels are important determinants of vascular smooth muscle membrane potential (Em ). A number of KV subunits are expressed in the plasma membrane of smooth muscle cells. Each subunit confers distinct kinetics and regulatory properties that allow for fine control of Em to orchestrate vascular tone. Modifications in KV subunit expression and/or channel activity can contribute to changes in vascular smooth muscle contractility in response to different stimuli and in diverse pathological conditions...
October 16, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/29044805/the-relationship-between-forearm-skin-speed-resolved-perfusion-and-oxygen-saturation-and-finger-arterial-pulsation-amplitudes-as-indirect-measures-of-endothelial-function
#14
Sara Bergstrand, Maria-Aurora Morales, Giuseppe Coppini, Marcus Larsson, Tomas Strömberg
OBJECTIVE: Endothelial function is important for regulating peripheral blood flow to meet varying metabolic demands and can be measured indirectly during vascular provocations. In this study, we compared the peripheral arterial tonometry finger response (EndoPAT) after a 5 min arterial occlusion to that from forearm skin comprehensive microcirculation analysis (Enhanced Perfusion and Oxygen Saturation, EPOS). METHOD: Measurements in 16 subjects with varying cardiovascular risk factors were done concurrently with both methods during arterial occlusion, while forearm skin was also evaluated during local heating RESULTS: Peak values for EPOS skin conventional perfusion and speed resolved total perfusion after the release of the occlusion, were significantly correlated to the EndoPAT reactive hyperemia index (RHI; ρ=0...
October 16, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/28985443/kv-channels-and-the-regulation-of-vascular-smooth-muscle-tone
#15
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
https://www.readbyqxmd.com/read/28976052/kv7-potassium-channels-as-signal-transduction-intermediates-in-the-control-of-microvascular-tone
#16
Kenneth L Byron, Lyubov I Brueggemann
Potassium channels are recognized as important regulators of cellular functions in most, if not all cell types. These cellular proteins assemble to form gated pores in the plasma membrane, which serve to regulate the flow of potassium ions (K(+) ) from the cytosol to the extracellular space. In vascular smooth muscle cells (VSMCs), the open state of potassium channels enables the efflux of K(+) and thereby establishes a negative resting voltage across the plasma membrane that inhibits the opening of voltage-sensitive Ca(2+) channels (VSCCs)...
October 4, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/28976050/assessment-of-the-test-retest-reliability-of-human-gingival-blood-flow-measurements-by-laser-speckle-contrast-imaging-in-a-healthy-cohort
#17
Eszter Molnár, Réka Fazekas, Zsolt Lohinai, Zsuzsanna Tóth, János Vág
OBJECTIVES: The reliability of gingival blood flow measured by Laser Speckle Contrast Imaging is unknown. Our aim was to investigate the effect of factors inherent in oral mucosa measurement on intra-day and inter-day reliability. METHODS: Gingival blood flow was measured in seventy healthy subjects. First, measurements were obtained by varying the incidence angle of imaging, using a lip retractor. Second, three snapshots were taken with closure of the mouth in-between and lips were retracted by a dental mirror...
October 4, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/28963858/kv-channel-trafficking-and-control-of-vascular-tone
#18
Raquibul Hasan, Jonathan H Jaggar
Membrane potential is a principal regulator of arterial contractility. Arterial smooth muscle cells express several different types of ion channel that control membrane potential, including voltage-gated K(+) (KV ) channels. KV channel activation leads to membrane hyperpolarization, resulting in inhibition of voltage-dependent calcium (Ca(2+) ) channels, a reduction in intracellular Ca(2+) concentration ([Ca(2+) ]i ) and vasodilation. In contrast, KV channel inhibition leads to membrane depolarization and vasoconstriction...
September 30, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/28926162/retinal-vessel-morphology-in-rheumatoid-arthritis-association-with-systemic-inflammation-subclinical-atherosclerosis-and-cardiovascular-risk
#19
Panagiota Anyfanti, Areti Triantafyllou, Eugenia Gkaliagkousi, Nikolaos Koletsos, Georgios Athanasopoulos, Xenophon Zabulis, Vasiliki Galanopoulou, Spyros Aslanidis, Stella Douma
OBJECTIVE: Quantification of retinal vessel morphology has emerged as a marker of cardiovascular health. We examined retinal microvascular diameters in RA, particularly in regard with systemic inflammation, subclinical atherosclerosis and cardiovascular risk. METHODS: Retinal images from RA patients and controls were processed using computerized software, to obtain central retinal arteriolar (CRAE) and venular (CRVE) equivalent and arteriovenous ratio (AVR). Subclinical atherosclerosis was assessed with carotid intima-media thickness (cIMT), and 10-year risk of general cardiovascular disease was calculated...
September 19, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/28801994/influence-of-feeding-hematocrit-and-perfusion-pressure-on-hematocrit-reduction-f%C3%A3-hraeus-effect-in-an-artificial-microvascular-network
#20
Walter H Reinhart, Nathaniel Z Piety, Sergey S Shevkoplyas
OBJECTIVE: Hct in narrow vessels is reduced due to concentration of fast-flowing RBCs in the center, and of slower flowing plasma along the wall of the vessel, which in combination with plasma skimming at bifurcations leads to the striking heterogeneity of local Hct in branching capillary networks known as the network Fåhraeus effect. We analyzed the influence of feeding Hct and perfusion pressure on the Fåhraeus effect in an AMVN. METHODS: RBC suspensions in plasma with Hcts between 20% and 70% were perfused at pressures of 5-60 cm H2 O through the AMVN...
November 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
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