HELIOTROPIC LEAF MOVEMENT RESPONSE TO H+ /ATPase activation, H+ /ATPase inhibition, AND K+ CHANNEL INHIBITION IN VIVO

1995 ◽  
Vol 82 (12) ◽  
pp. 1507-1513 ◽  
Author(s):  
Sarah L. Cronlund ◽  
Irwin N. Forseth
Keyword(s):  
K Channel ◽  
Leaf Movement ◽  
Movement Response ◽  
Channel Inhibition ◽  
Atpase Inhibition

In vivo Effects of Mutant HERG K+Channel Inhibition by Disopyramide in Patients with a Short QT-1 Syndrome: A Pilot Study

2007 ◽  
Vol 18 (11) ◽  
pp. 1157-1160 ◽  
Author(s):  
RAINER SCHIMPF ◽  
CHRISTIAN VELTMANN ◽  
CARLA GIUSTETTO ◽  
FIORENZO GAITA ◽  
MARTIN BORGGREFE ◽  
...  
Keyword(s):  
Pilot Study ◽  
K Channel ◽  
Channel Inhibition ◽  
In Vivo Effects

scholarly journals Role of Calcium in Phosphatidylserine Externalisation in Red Blood Cells from Sickle Cell Patients

Anemia ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Erwin Weiss ◽  
David Charles Rees ◽  
John Stanley Gibson
Keyword(s):  
Red Blood Cells ◽  
Sickle Cell ◽  
Blood Cells ◽  
Phosphatidylserine Exposure ◽  
Channel Inhibition ◽  
Cation Conductance ◽  
Gardos Channel ◽  
Cation Permeability

Phosphatidylserine exposure occurs in red blood cells (RBCs) from sickle cell disease (SCD) patients and is increased by deoxygenation. The mechanisms responsible remain unclear. RBCs from SCD patients also have elevated cation permeability, and, in particular, a deoxygenation-induced cation conductance which mediates entry, providing an obvious link with phosphatidylserine exposure. The role of was investigated using FITC-labelled annexin. Results confirmed high phosphatidylserine exposure in RBCs from SCD patients increasing upon deoxygenation. When deoxygenated, phosphatidylserine exposure was further elevated as extracellular [] was increased. This effect was inhibited by dipyridamole, intracellular chelation, and Gardos channel inhibition. Phosphatidylserine exposure was reduced in high saline. levels required to elicit phosphatidylserine exposure were in the low micromolar range. Findings are consistent with entry through the deoxygenation-induced pathway (), activating the Gardos channel. [] required for phosphatidylserine scrambling are in the range achievablein vivo.

Cation transport and volume regulation in sickle red blood cells

1993 ◽  
Vol 264 (2) ◽  
pp. C251-C270 ◽  
Author(s):  
C. H. Joiner
Keyword(s):  
Sickle Cell ◽  
Vascular Occlusion ◽  
Cell Swelling ◽  
K Channel ◽  
Transport Pathways ◽  
Root Cause ◽  
Sickle Cells ◽  
Cellular Dehydration ◽  
Mechanism Of Dehydration

Cellular dehydration is one of several pathological features of the sickle cell. Cation depletion is quite severe in certain populations of sickle cells and contributes to the rheological dysfunction that is the root cause of vascular occlusion in this disease. The mechanism of dehydration of sickle cells in vivo has not been ascertained, but three transport pathways may play important roles in this process. These include the deoxygenation-induced pathway that permits passive K+ loss and entry of Na+ and Ca2+; the K(+)-Cl- cotransport pathway, activated by acidification or cell swelling; and the Ca(2+)-activated K+ channel, or Gardos pathway, presumably activated by deoxygenation-induced Ca2+ influx. Recent evidence suggests that these pathways may interact in vivo. Heterogeneity exists among sickle cells as to the rate at which they become dense, suggesting that other factors may affect the activity or interactions of these pathways. Understanding the mechanism of dehydration of sickle cells may provide opportunities for pharmacological manipulation of cell volume to mitigate some of the symptoms of sickle cell disease.

Involvement of actin cytoskeleton in modulation of apical K channel activity in rat collecting duct

1994 ◽  
Vol 267 (4) ◽  
pp. F592-F598 ◽  
Author(s):  
W. H. Wang ◽  
A. Cassola ◽  
G. Giebisch
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Filaments ◽  
Cytochalasin B ◽  
Collecting Duct ◽  
K Channel ◽  
Cortical Collecting Duct ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
Channel Inhibition ◽  
Inside Out

We have employed the patch-clamp technique to investigate the role of the actin cytoskeleton in the modulation of the low-conductance K+ channel in the apical membrane of the rat cortical collecting duct (CCD). This K+ channel is inactivated by application of cytochalasin B or D, both compounds known to disrupt actin filaments. The effect of both cytochalasins, B and D, was fully reversible in cell-attached patches, but channel activity could not be fully restored in excised membrane patches. The effect of cytochalasins on channel activity was specific and resulted from depolymerization of the actin cytoskeleton, since application of 10 microM chaetoglobosin C, a cytochalasin analogue that does not depolymerize the actin filaments, had no effect on channel activity in inside-out patches. Addition of either actin monomers or of the polymerizing actin filaments in inside-out patches to the cytosolic medium had no effect on channel activity. This suggests that cytochalasin B- or D-induced inactivation of apical K+ channels is not caused by obstruction of the channel pore by actin. We also observed that channel inhibition by cytochalasin B or D could be blocked by pretreatment with 5 microM phalloidin, a compound that stabilizes actin filaments. We conclude that apical K+ channel activity depends critically on the integrity of the actin cytoskeleton.

scholarly journals In Vivo Measurements Of a Ca2+- And Voltage-Activated K+ Channel Intramolecular Distances Using Genetically Encoded Reporters

2009 ◽  
Vol 96 (3) ◽  
pp. 474a
Author(s):  
Cristian A. Zaelzer ◽  
Walter Sandtner ◽  
Clark Hyde ◽  
Ramon Latorre ◽  
Francisco Bezanilla
Keyword(s):  
K Channel ◽  
In Vivo Measurements

scholarly journals Kv5, Kv6, Kv8, and Kv9 subunits: No simple silent bystanders

2016 ◽  
Vol 147 (2) ◽  
pp. 105-125 ◽  
Author(s):  
Elke Bocksteins
Keyword(s):  
Therapeutic Strategies ◽  
K Channel ◽  
Biophysical Properties ◽  
Tissue Specific ◽  
Voltage Gated ◽  
Novel Treatments ◽  
Novel Therapeutic Strategies ◽  
Different Tissues ◽  
Novel Therapeutic

Members of the electrically silent voltage-gated K+ (Kv) subfamilies (Kv5, Kv6, Kv8, and Kv9, collectively identified as electrically silent voltage-gated K+ channel [KvS] subunits) do not form functional homotetrameric channels but assemble with Kv2 subunits into heterotetrameric Kv2/KvS channels with unique biophysical properties. Unlike the ubiquitously expressed Kv2 subunits, KvS subunits show a more restricted expression. This raises the possibility that Kv2/KvS heterotetramers have tissue-specific functions, making them potential targets for the development of novel therapeutic strategies. Here, I provide an overview of the expression of KvS subunits in different tissues and discuss their proposed role in various physiological and pathophysiological processes. This overview demonstrates the importance of KvS subunits and Kv2/KvS heterotetramers in vivo and the importance of considering KvS subunits and Kv2/KvS heterotetramers in the development of novel treatments.

scholarly journals M-Type K+ Channel Openers: In Vivo Neuroprotective Role During Cerebrovascular Stroke

2012 ◽  
Vol 102 (3) ◽  
pp. 132a
Author(s):  
Sonya M. Bierbower ◽  
Frank S. Choveau ◽  
Mark S. Shapiro
Keyword(s):  
K Channel ◽  
Type K ◽  
Cerebrovascular Stroke

scholarly journals Genetic dissection reveals unexpected influence of β subunits on KCNQ1 K + channel polarized trafficking in vivo

2010 ◽  
Vol 25 (2) ◽  
pp. 727-736 ◽  
Author(s):  
Torsten K. Roepke ◽  
Elizabeth C. King ◽  
Kerry Purtell ◽  
Vikram A. Kanda ◽  
Daniel J. Lerner ◽  
...  
Keyword(s):  
K Channel ◽  
Genetic Dissection ◽  
Polarized Trafficking

Dynamic regulation of the voltage-gated Kv2.1 potassium channel by multisite phosphorylation

2007 ◽  
Vol 35 (5) ◽  
pp. 1064-1068 ◽  
Author(s):  
D.P. Mohapatra ◽  
K.-S. Park ◽  
J.S. Trimmer
Keyword(s):  
Neuronal Excitability ◽  
Critical Role ◽  
Functional Characterization ◽  
K Channel ◽  
Delayed Rectifier ◽  
Dynamic Regulation ◽  
Voltage Gated ◽  
Voltage Dependent ◽  
Specific Regulation

Voltage-gated K+ channels are key regulators of neuronal excitability. The Kv2.1 voltage-gated K+ channel is the major delayed rectifier K+ channel expressed in most central neurons, where it exists as a highly phosphorylated protein. Kv2.1 plays a critical role in homoeostatic regulation of intrinsic neuronal excitability through its activity- and calcineurin-dependent dephosphorylation. Here, we review studies leading to the identification and functional characterization of in vivo Kv2.1 phosphorylation sites, a subset of which contribute to graded modulation of voltage-dependent gating. These findings show that distinct developmental-, cell- and state-specific regulation of phosphorylation at specific sites confers a diversity of functions on Kv2.1 that is critical to its role as a regulator of intrinsic neuronal excitability.

scholarly journals K+ channel blockade in the NTS alters efficacy of two cardiorespiratory reflexes in vivo

1998 ◽  
Vol 274 (3) ◽  
pp. R677-R685 ◽  
Author(s):  
James W. Butcher ◽  
Julian F. R. Paton
Keyword(s):  
Potassium Channel ◽  
Neuronal Excitability ◽  
Baroreceptor Reflex ◽  
Right Atrial ◽  
K Channel ◽  
Reflex Bradycardia ◽  
Potassium Conductances ◽  
Voltage Dependent

We investigated the role of potassium conductances in the nucleus of the solitary tract (NTS) in determining the efficacy of the baroreceptor and cardiopulmonary reflexes in anesthetized rats. The baroreceptor reflex was elicited with an intravenous injection of phenylephrine to evoke a reflex bradycardia, and the cardiopulmonary reflex was evoked with a right atrial injection of phenylbiguanide. Microinjection of two Ca-dependent potassium channel antagonists (apamin and charybdotoxin) into the NTS potentiated the baroreceptor reflex bradycardia. This may reflect the increased neuronal excitability observed previously in vitro with these blockers. In contrast, the Ca-dependent potassium channel antagonists attenuated the cardiopulmonary reflex, whereas voltage-dependent potassium channel antagonists (4-aminopyridine and dendrotoxin) attenuated both the baro- and cardiopulmonary reflexes when microinjected into the NTS. The possibility that the reflex attenuation observed indicates a predominant distribution of certain potassium channels on γ-aminobutyric acid interneurons is discussed.

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