scholarly journals FM Dye Cycling at the Synapse: Comparing High Potassium Depolarization, Electrical and Channelrhodopsin Stimulation

10.3791/57765 ◽  
2018 ◽  
Author(s):  
Danielle L. Kopke ◽  
Kendal Broadie
Keyword(s):  
Potassium Depolarization ◽  
High Potassium

Nitrendipine blocks high potassium contractures but not twitches in rat skeletal muscle

1988 ◽  
Vol 66 (9) ◽  
pp. 1210-1213 ◽  
Author(s):  
G. B. Frank ◽  
L. Konya ◽  
T. Subrahmanyam Sudha
Keyword(s):  
Skeletal Muscle ◽  
Calcium Ions ◽  
Calcium Uptake ◽  
Channel Blocker ◽  
Mechanical Response ◽  
Extracellular Calcium ◽  
The Other ◽  
Rat Skeletal Muscle ◽  
Potassium Depolarization ◽  
High Potassium

The effects of the organic calcium channel blocker nitrendipine was tested on electrically evoked twitches and on potassium depolarization-induced contractures of rat lumbricalis muscles. Nitrendipine (10−7 to 5 × 10−5 M) blocked only the potassium contractures. It was concluded that blocking calcium uptake through the slow voltage-senstitive calcium channels during potassium depolarization blocks the mechanical response of the muscle. Thus extracellular calcium ions are required for the excitation–contraction (E–C) coupling during depolarization contractures. On the other hand, electrically evoked twitches were not affected by nitrendipine; therefore, extracellular calcium ions entering via the slow voltage-sensitive channels are not required for E–C coupling during the twitch.

scholarly journals Calcium diffusion in uterine smooth muscle sheets.

1982 ◽  
Vol 80 (2) ◽  
pp. 257-277 ◽  
Author(s):  
S Kato ◽  
T Ogasawara ◽  
T Osa
Keyword(s):  
Potassium Depolarization ◽  
High Potassium ◽  
Tension Development ◽  
Uterine Smooth Muscle ◽  
Rate Limiting Step ◽  
Ca Addition ◽  
Calcium Diffusion ◽  
Apparent Diffusion ◽  
The Difference ◽  
Rate Limiting

The potassium contracture in the longitudinal muscle of estrogen-treated rat uterus was kinetically investigated. The rates of tension development after Ca addition and relaxation after Ca removal were measured under the high-potassium depolarization. Both rates decreased with an increase in preparation thickness. The relaxation rate had only a slight dependence on temperature. On the contrary, both relaxation and contraction rates in a contraction induced by an electrical stimulation strongly depended on temperature, but not on preparation size. These results suggest that the Ca diffusion process in the extracellular space is the rate-limiting step in relaxation of Ca-dependent contracture under potassium depolarization. The diffusion model, in which the effect of the unstirred layer was considered, could quantitatively explain the experimental results. The apparent diffusion coefficient in the muscle sheet was estimated to be approximately 3 x 10(-7) cm2/s. The difference from that in aqueous solution is discussed.

scholarly journals EFFECTS OF HIGH POTASSIUM DEPOLARIZATION, CARBACHOL AND OXYTOCIN ON THE LANTHANUM-RESISTANT 45Ca FRACTION IN RAT MYOMETRIUM

1983 ◽  
Vol 33 (1) ◽  
pp. 1-8
Author(s):  
Tsutomu URUNO ◽  
Teruyuki SEKIGUCHI ◽  
Nobuyoshi SUNAGANE ◽  
Yutaka MATSUOKA ◽  
Kazuhiko KUBOTA
Keyword(s):  
Potassium Depolarization ◽  
High Potassium

scholarly journals The Influence of High Potassium Depolarization and Acetylcholine on Calcium Exchange in the Rat Uterus

1966 ◽  
Vol 49 (6) ◽  
pp. 1299-1317 ◽  
Author(s):  
CASEY van BREEMEN ◽  
E. E. DANIEL
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Membrane ◽  
Cell Membranes ◽  
Cytoplasmic Calcium ◽  
Calcium Efflux ◽  
Rat Uterus ◽  
Potassium Depolarization ◽  
High Potassium ◽  
Calcium Exchange

Net and radioactive calcium movements were studied in the rat uterus during stimulation with acetylcholine and high potassium solutions. High potassium did not affect the efflux of intracellular Ca45, but was able to release Ca45 from a small parallel Ca fraction which was believed to be located in the cell membranes. High potassium did markedly slow the influx of Ca45 and caused a net calcium efflux. Acetylcholine had no effect on calcium movements in polarized myometrium, but it increased the Ca45 influx in depolarized uteri. Ca45 taken up during contraction exchanged more slowly during subsequent efflux than Ca45 taken up at rest. The results were interpreted as supporting the hypothesis that myometrial contraction is induced by a release of calcium from the inside of the cell membrane and the endoplasmic reticulum, and relaxation follows the removal of ionic cytoplasmic calcium by these same structures.

Release of exogenously supplied [3H]glutamate and endogenous glutamate from tissue slices of the cestode Hymenolepis diminuta

1988 ◽  
Vol 66 (7) ◽  
pp. 889-894 ◽  
Author(s):  
Rodney A. Webb
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamate Release ◽  
Hymenolepis Diminuta ◽  
Acidic Amino Acid ◽  
Tissue Slices ◽  
Potassium Depolarization ◽  
High Potassium ◽  
Calcium Dependent ◽  
Sodium Dependent

The effect of high potassium depolarization on the release of exogenously supplied [3H]glutamate and endogenous glutamate from tissue slices of the cestode Hymenolepis diminuta was examined. Increasing concentrations of potassium stimulated the release of radiolabel from tissues preloaded with [3H]glutamate. This release was by a partially calcium-dependent, magnesium-antagonized process. In the presence of tetrodotoxin, or absence of sodium, release of radiolabel was depressed, presumably by blockade of sodium-dependent neuronal potentials. The release of glutamate of both exogenous and endogenous origin was specifically and significantly elevated by high potassium; glutamate release was significantly depressed in calcium-free saline. The release of other amino acids of endogenous origin, including aspartate, was not elevated by high potassium. Collectively the data provide strong evidence for glutamate to be viewed as the only acidic amino acid neurotransmitter candidate in the cestodes.

scholarly journals Effects of high potassium depolarization, carbachol and oxytocin on the lanthanum-resistant 45Ca fraction in rat myometrium.

1983 ◽  
Vol 33 (1) ◽  
pp. 1-8
Author(s):  
Tsutomu URUNO ◽  
Teruyuki SEKIGUCHI ◽  
Nobuyoshi SUNAGANE ◽  
Yutaka MATSUOKA ◽  
Kazuhiko KUBOTA
Keyword(s):  
Potassium Depolarization ◽  
High Potassium

Some Effects of the Ionic Composition of the Extracellular Fluid on the Electrical Activity of the Cockroach Abdominal Nerve Cord

1962 ◽  
Vol 39 (4) ◽  
pp. 631-641
Author(s):  
J. E. TREHERNE
Keyword(s):  
Nerve Cord ◽  
Periplaneta Americana ◽  
Ionic Composition ◽  
Conduction Block ◽  
Extracellular Fluid ◽  
Potassium Ions ◽  
Rapid Loss ◽  
Potassium Depolarization ◽  
High Potassium ◽  
Nerve Sheath

1. Irrigation of abdominal ganglia of Periplaneta Americana with salines containing excess potassium ions resulted in the development of a reversible conduction block. Removal of portions of the cellular and fibrous nerve sheath produced an accelerated potassium depolarization as described by Twarog & Roeder (1956). 2. Elevation of the cation concentrations to correspond to the extracellular levels resulted in delayed conduction block in desheathed preparations irrigated with highpotassium saline. At 70 mM./l. K the rate of depolarization was delayed to approximately half that of intact ganglia. At extremely high potassium concentrations this effect became relatively small. 3. It is suggested that the enhanced rates of potassium depolarization obtained in desheathed preparations partly result from the changed ionic composition of the extracellular fluid resulting from the desheathing procedure. The possible additional factors involved in the desheathing procedure are discussed. 4. 50 mM./l. acetylcholine had little effect on the synaptic transmission in intact terminal abdominal ganglia but caused rapid loss of conduction in desheathed preparations. Injection of equivalent amounts of acetylcholine beneath the nerve sheath did not cause rapid conduction block, and it is suggested that the effects of desheathing are not necessarily caused by the removal of a relatively impermeable superficial diffusion barrier.

High potassium levels silence T cells

2016 ◽  
Vol 94 (37) ◽  
Keyword(s):  
T Cells ◽  
High Potassium
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