A small synthetic molecule forms selective potassium channels to regulate cell membrane potential and blood vessel tone

2014 ◽  
Vol 12 (41) ◽  
pp. 8174-8179 ◽  
Author(s):  
Hui-Yan Zha ◽  
Bing Shen ◽  
Kwok-Hei Yau ◽  
Shing-To Li ◽  
Xiao-Qiang Yao ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Potassium Channels ◽  
Cell Membrane ◽  
Blood Vessel ◽  
Muscle Cell ◽  
Cell Membrane Potential ◽  
Vascular Muscle ◽  
Selective Channel ◽  
Synthetic Molecule ◽  
Muscle Cell Membrane

A molecule forms a K+-selective channel in the cell membrane to regulate vascular muscle cell membrane potential and blood vessel tone.

A synthetic transmembrane segment derived from TRPV4 channel self-assembles into potassium-like channels to regulate vascular smooth muscle cell membrane potential

2014 ◽  
Vol 2 (24) ◽  
pp. 3809-3818 ◽  
Author(s):  
Zhiqiang Yu ◽  
Jie Li ◽  
Jinhang Zhu ◽  
Min Zhu ◽  
Feifei Jiang ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cell ◽  
Muscle Cell ◽  
Vascular Smooth Muscle Cell ◽  
Cell Membrane Potential ◽  
Trpv4 Channel ◽  
Muscle Cell Membrane

A synthetic K+-like channel mediates K+outward flow to regulate vascular smooth muscle cell membrane potential, blood vessel tone and blood pressure.

Ammonia movement and distribution after exercise across white muscle cell membranes in rainbow trout

1996 ◽  
Vol 271 (3) ◽  
pp. R738-R750 ◽  
Author(s):  
Y. Wang ◽  
G. J. Heigenhauser ◽  
C. M. Wood
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Intracellular Ph ◽  
Muscle Cell ◽  
Cell Membranes ◽  
White Muscle ◽  
Extracellular Ph ◽  
Posterior Portion ◽  
Arterial Inflow ◽  
Muscle Cell Membrane

Manipulations of pH and electrical gradients in a perfused preparation were used to analyze the factors controlling ammonia distribution and flux in trout white muscle after exercise. Trout were exercised to exhaustion, and then an isolated-perfused white muscle preparation with discrete arterial inflow and venous outflow was made from the posterior portion of the tail. The tail-trunks were perfused with low (7.4)-, medium (7.9)-, and high (8.4)-pH saline, achieved by varying HCO3- concentration ([HCO3-]) at constant Pco2. Intracellular and extracellular pH, ammonia, CO2, K+, Na+, and Cl- were measured. Muscle intracellular pH was not affected by changes in extracellular pH. Increasing extracellular pH caused a decrease in the transmembrane NH3 partial pressure (PNH3) gradient and a decrease in ammonia efflux. When extracellular K+ concentration was increased from 3.5 to 15 mM in the medium-pH group, a depolarization of the muscle cell membrane potential from -92 to -60 mV and a 0.1-unit depression in intracellular pH occurred. Ammonia efflux increased despite a marked reduction in the PNH3 gradient. Amiloride (10(-4) M) had no effect, indicating that Na+/H(+)-NH4+ exchange does not participate in ammonia transport in this system. A comparison of observed intracellular-to-extracellular ammonia distribution ratios with those modeled according to either pH or Nernst potential distributions supports a model in which ammonia distribution across white muscle cell membranes is affected by both pH and electrical gradients, indicating that the membranes are permeable to both NH3 and NH4+. Membrane potential, acting to retain high levels of NH4+ in the intracellular compartment, appears to have the dominant influence during the postexercise period. However, at rest, the pH gradient may be more important, resulting in much lower intracellular ammonia levels and distribution ratios. We speculate that the muscle cell membrane NH3-to-NH4+ permeability ratio in trout may change between the rest and postexercise condition.

Modulation of cell membrane potential in cultured vascular endothelium

1996 ◽  
Vol 270 (3) ◽  
pp. C819-C824 ◽  
Author(s):  
L. Vaca ◽  
A. Licea ◽  
L. D. Possani
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Cell Membrane Potential ◽  
Resting Potential ◽  
Similar Response ◽  
Aortic Endothelial Cells ◽  
Ionic Conductances ◽  
Selective Channel ◽  
Inwardly Rectifying

The present study explores the role of different ionic conductances in the regulation of membrane potential under resting conditions and after bradykinin (BK) or thapsigargin (TG) stimulation of cultured bovine aortic endothelial cells. Under resting conditions, the cell membrane potential observed was -62+/- 5 mV. The main conductance under these conditions is an inwardly rectifying potassium (IRK) channel. Application of 50 nM BK induced a transient hyperpolarization to -87 +/- 4 mV followed by sustained depolarization to -35 +/- 5 mV. The transient hyperpolarization was eliminated by 1 microM noxiustoxin, a blocker of calcium-activated postassium channels (K(Ca)). the sustained depolarization induced by BK was prevented by incubating the cells with the calcium channel blocker lanthanum. TG evoked a similar response in membrane potential, with the exception that the onset of the hyperpolarization was slower compared with BK. The results presented here indicate that the cell resting potential is maintained at -62 +/- 2 mV by the IRK channel. BK or TG stimulation induces a transient hyperpolarization of approximately -20 mV produced by activation of a KCa. This hyperpolarization is followed by a sustained depolarization produced by activation of a calcium-selective channel sensitive to lanthanum.

Unusual potassium channels mediate nonadrenergic noncholinergic nerve-mediated inhibition in opossum esophagus

1985 ◽  
Vol 63 (2) ◽  
pp. 107-112 ◽  
Author(s):  
J. Jury ◽  
L. P. Jager ◽  
E. E. Daniel
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Guinea Pig ◽  
Smooth Muscle Cell ◽  
Muscle Cell ◽  
Membrane Resistance ◽  
Potassium Ion ◽  
Ion Permeability ◽  
Muscle Cell Membrane

Field stimulation of the circular muscle of the opossum esophagus produces a transient hyperpolarization (inhibitory junction potential, IJP) followed by an "off" depolarization. A similar nonadrenergic, noncholinergic (NANC) response in guinea pig taenia caecum has been shown to be due to an increase in the potassium ion permeability of the smooth muscle cell membrane. Double sucrose gap studies showed a decrease in resistance during the IJP, and a reversal at an estimated membrane potential of about −90 mV (4 mM K+). The reversal potential was dependent on the extracellular potassium concentration, shifting to −75 mV when the potassium in the superfusion medium was increased to 10 mM. The IJP in the opossum esophageal circular smooth muscle is therefore like the IJP of the guinea pig taenia caecum in that it is probably due to a selective increase in potassium ion permeability. Potassium conductance blocking agents, tetraethylammonium chloride (TEA, 20 mM) and 4-aminopyridine (4-AP, 5 mM) both caused a depolarization of the smooth muscle cell membrane, but TEA increased the membrane resistance, whereas 4-AP did not affect the membrane conductance in a consistent way. A decrease in IJP amplitude owing to these agents was not apparent. Apamin (10 μM) did not affect the membrane potential, the membrane resistance, or the IJP. Quinine (0.1 mM) produced effects quantitatively similar to those of TEA. Quinine (1 mM) did abolish the IJP, however, this was likely due to a blockade of impulse transmission of the intramural nerves. These results suggest that the receptor-operated channels opened by the NANC-nerve mediator in this tissue are unusual in that they are different from those functioning to maintain the resting membrane potential and they differ from those involved in the IJP in the guinea pig taenia caecum.

Muscle water and electrolytes following varied levels of dehydration in man

1976 ◽  
Vol 40 (1) ◽  
pp. 6-11 ◽  
Author(s):  
D. L. Costill ◽  
R. Cote ◽  
W. Fink
Keyword(s):  
Body Weight ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Muscle Cell ◽  
Muscle Tissue ◽  
Muscle Biopsy ◽  
Resting Membrane Potential ◽  
Muscle Water ◽  
Percent Decrease ◽  
Muscle Cell Membrane

In an effort to assess the effects of dehydration on the content of water and electrolytes (Na+, K+, Cl-, and Mg2+) in plasma and muscle tissue, eight men exercised in the heat (39.5 degrees C, 25%). Blood urine, and muscle biopsy samples were obtained before exercise and after the subjects had reduced their body weight by 2.2, 4.1, and 5.8%. On the average, plasma and muscle water (H2Om) contents were found to decline 2.4 and 1.2% for each percent decrease in body weight. Muscle sodium (Na+m) and chloride (Cl-m) content remained unchanged with dehydration, while muscle magnesium (Mg2+m) declined 12% as a result of the 5.8% dehydration. In terms of intracellular concentrations, K+i increased 7.2 and 10.6% at the 2.2 and 4.1% dehydration levels, respectively. Calculations of the resting membrane potential suggest that the water and electrolyte losses observed in these studies do not significantly alter the excitability of the muscle cell membrane.

scholarly journals Novel autoantibodies against muscle-cell membrane proteins in patients with myositis

1996 ◽  
Vol 39 (11) ◽  
pp. 1860-1868 ◽  
Author(s):  
Bruno Stuhlmüller ◽  
Ricardo Jerez ◽  
Gert Hausdorf ◽  
Hans-R. Barthel ◽  
Michael Meurer ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Cell Membrane ◽  
Muscle Cell ◽  
Cell Membrane Proteins ◽  
Muscle Cell Membrane
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