scholarly journals Transient kinetics of an inward rectifier K+ channel in the myocardial cell membrane.

1984 ◽  
Vol 34 (6) ◽  
pp. 1123-1127 ◽  
Author(s):  
Junichi TANIGUCHI ◽  
Takao NAKAMURA
Keyword(s):  
Cell Membrane ◽  
Myocardial Cell ◽  
Inward Rectifier ◽  
K Channel ◽  
Transient Kinetics ◽  
Kinetics Of

scholarly journals Potassium current and the effect of cesium on this current during anomalous rectification of the egg cell membrane of a starfish.

1976 ◽  
Vol 67 (6) ◽  
pp. 621-638 ◽  
Author(s):  
S Hagiwara ◽  
S Miyazaki ◽  
N P Rosenthal
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Time Dependent ◽  
Equilibrium Potential ◽  
K Channel ◽  
Egg Cell ◽  
Dimensionless Number ◽  
First Order Kinetics ◽  
K Current ◽  
Kinetics Of

The kinetics of the membrane current during the anomalous or inward-going rectification of the K current in the egg cell membrane of the starfish Mediaster aequalis were analyzed by voltage clamp. The rectification has instantaneous and time-dependent components. The time-dependent increase in the K conductance for the negative voltage pulse as well as the decrease in the conductance for the positive pulse follows first-order kinetics. The steady-state conductance increases as the membrane potential becomes more negative and reaches the saturation value at about -40 mV more negative than the K equilibrium potential, V(K). The entire K conductance can be expressed by g(K).n; g g(K) represents the component for the time-independent conductance which depends on V-V(K) and [K+]o, and n is a dimensionless number (1 is greater than or equal to n is greater than or equal to 0) and determined by two rate constants which depend only on V-V(K). Cs+ does not carry any significant current through the K channel but blocks the channel at low concentration in the external medium. The blocking effect increases as the membrane potential is made more negative and the potential-dependent blocking by the external Cs+ also has instantaneous and time-dependent components.

Time Resolved Kinetics of Direct G β1γ2 Interactions with the Carboxyl Terminus of Kir3.4 Inward Rectifier K + Channel Subunits

1996 ◽  
Vol 35 (7) ◽  
pp. 923-931 ◽  
Author(s):  
C.A. DOUPNIK ◽  
C.W. DESSAUER ◽  
V.Z. SLEPAK ◽  
A.G. GILMAN ◽  
N. DAVIDSON ◽  
...  
Keyword(s):  
Inward Rectifier ◽  
Carboxyl Terminus ◽  
K Channel ◽  
Time Resolved ◽  
Kinetics Of

scholarly journals Kinetics of Inward-Rectifier K+ Channel Block by Quaternary Alkylammonium Ions

2001 ◽  
Vol 117 (5) ◽  
pp. 395-406 ◽  
Author(s):  
Donglin Guo ◽  
Zhe Lu
Keyword(s):  
Apparent Rate Constant ◽  
Inward Rectifier ◽  
K Channel ◽  
Remarkable Difference ◽  
Channel Block ◽  
Diffusion Limited ◽  
Methylene Groups ◽  
Kinetics Of ◽  
Binding Locus ◽  
Limited Process

We examined block of two inward-rectifier K+ channels, IRK1 and ROMK1, by a series of intracellular symmetric quaternary alkylammonium ions (QAs) whose side chains contain one to five methylene groups. As shown previously, the ROMK1 channels bind larger QAs with higher affinity. In contrast, the IRK1 channels strongly select TEA over smaller or larger QAs. This remarkable difference in QA selectivity between the two channels results primarily from differing QA unbinding kinetics. The apparent rate constant for binding (kon) of all examined QAs is significantly smaller than expected for a diffusion-limited process. Furthermore, a large (∼30-fold) drop in kon occurs when the number of methylene groups in QAs increases from three to four. These observations argue that between the intracellular solution and the QA-binding locus, there exists a constricted pathway, whose dimension (∼9 Å) is comparable to that of a K+ ion with a single H2O shell.

scholarly journals Weak Electromagnetic Fields Accelerate Fusion of Myoblasts

2021 ◽  
Vol 22 (9) ◽  
pp. 4407
Author(s):  
Dana Adler ◽  
Zehavit Shapira ◽  
Shimon Weiss ◽  
Asher Shainberg ◽  
Abram Katz
Keyword(s):  
Skeletal Muscle ◽  
Cell Membrane ◽  
Cell Fusion ◽  
Electromagnetic Fields ◽  
Muscle Development ◽  
K Channel ◽  
Gambogic Acid ◽  
Cell Replication ◽  
Myotube Formation ◽  
Primary Myoblast

Weak electromagnetic fields (WEF) alter Ca2+ handling in skeletal muscle myotubes. Owing to the involvement of Ca2+ in muscle development, we investigated whether WEF affects fusion of myoblasts in culture. Rat primary myoblast cultures were exposed to WEF (1.75 µT, 16 Hz) for up to six days. Under control conditions, cell fusion and creatine kinase (CK) activity increased in parallel and peaked at 4–6 days. WEF enhanced the extent of fusion after one and two days (by ~40%) vs. control, but not thereafter. Exposure to WEF also enhanced CK activity after two days (almost four-fold), but not afterwards. Incorporation of 3H-thymidine into DNA was enhanced by one-day exposure to WEF (~40%), indicating increased cell replication. Using the potentiometric fluorescent dye di-8-ANEPPS, we found that exposure of cells to 150 mM KCl resulted in depolarization of the cell membrane. However, prior exposure of cells to WEF for one day followed by addition of KCl resulted in hyperpolarization of the cell membrane. Acute exposure of cells to WEF also resulted in hyperpolarization of the cell membrane. Twenty-four hour incubation of myoblasts with gambogic acid, an inhibitor of the inward rectifying K+ channel 2.1 (Kir2.1), did not affect cell fusion, WEF-mediated acceleration of fusion or hyperpolarization. These data demonstrate that WEF accelerates fusion of myoblasts, resulting in myotube formation. The WEF effect is associated with hyperpolarization but WEF does not appear to mediate its effects on fusion by activating Kir2.1 channels.

Transient kinetics of ATP hydrolysis by covalently crosslinked actomyosin complex in water and 40% ethylene glycol by the rapid flow quench method

Biochemistry ◽  
1985 ◽  
Vol 24 (14) ◽  
pp. 3814-3820 ◽  
Author(s):  
J. A. Biosca ◽  
F. Travers ◽  
T. E. Barman ◽  
R. Bertrand ◽  
E. Audemard ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Atp Hydrolysis ◽  
Transient Kinetics ◽  
Actomyosin Complex ◽  
Rapid Flow ◽  
Kinetics Of ◽  
Quench Method
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