scholarly journals Transient, Consequential Increases in Extracellular Potassium Ions Accompany Channelrhodopsin2 Excitation

Cell Reports ◽  
2019 ◽  
Vol 27 (8) ◽  
pp. 2249-2261.e7 ◽  
Author(s):  
J. Christopher Octeau ◽  
Mohitkumar R. Gangwani ◽  
Sushmita L. Allam ◽  
Duy Tran ◽  
Shuhan Huang ◽  
...  
Keyword(s):  
Extracellular Potassium ◽  
Potassium Ions

Modulation of Jellyfish Potassium Channels by External Potassium Ions

1999 ◽  
Vol 82 (4) ◽  
pp. 1728-1739 ◽  
Author(s):  
Nikita G. Grigoriev ◽  
J. David Spafford ◽  
Andrew N. Spencer
Keyword(s):  
Potassium Channels ◽  
Motor Neurons ◽  
Fruit Fly ◽  
Site Directed Mutagenesis ◽  
High Threshold ◽  
Extracellular Potassium ◽  
Potassium Ions ◽  
Polyorchis Penicillatus ◽  
State Dependent ◽  
Inactivation Mechanism

The amplitude of an A-like potassium current ( I Kfast) in identified cultured motor neurons isolated from the jellyfish Polyorchis penicillatus was found to be strongly modulated by extracellular potassium ([K+]out). When expressed in Xenopus oocytes, two jellyfish Shaker-like genes, jShak1 and jShak2, coding for potassium channels, exhibited similar modulation by [K+]out over a range of concentrations from 0 to 100 mM. jShak2-encoded channels also showed a decreased rate of inactivation and an increased rate of recovery from inactivation at high [K+]out. Using site-directed mutagenesis we show that inactivation of jShak2 can be ascribed to an unusual combination of a weak “implicit” N-type inactivation mechanism and a strong, fast, potassium-sensitive C-type mechanism. Interaction between the two forms of inactivation is responsible for the potassium dependence of cumulative inactivation. Inactivation of jShak1 was determined primarily by a strong “ball and chain” mechanism similar to fruit fly Shaker channels. Experiments using fast perfusion of outside-out patches with jShak2 channels were used to establish that the effects of [K+]out on the peak current amplitude and inactivation were due to processes occurring at either different sites located at the external channel mouth with different retention times for potassium ions, or at the same site(s) where retention time is determined by state-dependent conformations of the channel protein. The possible physiological implications of potassium sensitivity of high-threshold potassium A-like currents is discussed.

scholarly journals Cortex-wide Changes in Extracellular Potassium Ions Parallel Brain State Transitions in Awake Behaving Mice

Cell Reports ◽  
2019 ◽  
Vol 28 (5) ◽  
pp. 1182-1194.e4 ◽  
Author(s):  
Rune Rasmussen ◽  
Eric Nicholas ◽  
Nicolas Caesar Petersen ◽  
Andrea Grostøl Dietz ◽  
Qiwu Xu ◽  
...  
Keyword(s):  
State Transitions ◽  
Brain State ◽  
Extracellular Potassium ◽  
Potassium Ions

Extracellular potassium ions mediate specific neuronal interaction

Science ◽  
1982 ◽  
Vol 216 (4541) ◽  
pp. 80-82 ◽  
Author(s):  
Y Yarom ◽  
M. Spira
Keyword(s):  
Extracellular Potassium ◽  
Potassium Ions

scholarly journals Further observations on the inhibitory effect of extracellular potassium ions on glycine uptake by mouse ascites-tumour cells

1969 ◽  
Vol 114 (4) ◽  
pp. 807-814 ◽  
Author(s):  
A A Eddy ◽  
M. C. Hogg
Keyword(s):  
Initial Rate ◽  
Inhibitory Effect ◽  
Sodium Cyanide ◽  
Tumour Cells ◽  
Extracellular Potassium ◽  
Potassium Ions ◽  
Atp Content ◽  
Entry Rate ◽  
Mouse Ascites ◽  
Ascites Tumour Cells

1. The initial rate of uptake of glycine by the tumour cells was measured as a function of the Na+ and K+ concentrations in the solution in which the cells were suspended. When [Gly] was 1mm or 12mm, the rate in the absence of Na+ was independent of [K+] and about 3% or 10% respectively of the rate when [Na+] was 150m-equiv./l. 2. The Na+-dependent glycine entry rate, v, at a given value of [Na+] was successively lowered when [K+] was increased from 8 to 47 to 96m-equiv./l. A kinetic analysis indicated that K+ competitively inhibited the action of Na+. The results were in fair agreement with previous determinations of the kinetic parameters. 3. The presence of 2mm-sodium cyanide and 10mm-2-deoxyglucose lowered the cellular ATP content to less than 3% of the value in the respiring cells. Although v was then about 50% smaller, the relative effects of K+ and Na+ on the system were similar to those observed during respiration. 4. A theoretical analysis indicated that the variation of v with [K+] is not a reliable guide to the extent to which the K+ gradient between the cells and their environment may contribute to the net transport of glycine.

Aminergic Regulation of Anoxic Coma in Locusta migratoria

2016 ◽  
Author(s):  
Tina Hu
Keyword(s):  
Cortical Spreading Depression ◽  
Spreading Depression ◽  
Locusta Migratoria ◽  
Control Group ◽  
Extracellular Potassium ◽  
Potassium Ions ◽  
Treatment Groups ◽  
Anoxic Coma ◽  
Cellular Stressors

Cortical spreading depression (CSD), a phenomenon underlying stroke and head trauma, involves the depolarization of neurons in one localized area that rapidly propagates to and depolarizes surrounding cells. CSD is characterized by a sudden increased concentration of extracellular potassium ions (K+), which is also generated by cellular stressors like anoxia. The purpose of this study is to examine the role of biogenic amines in the time to succumb and time to recover from anoxic coma in Locusta migratoria, a locust which is regularly exposed to anoxia in its natural environment and survive by entering a reversible coma (a spreading‐depression like event). Locusts were first immersed in water for 30 minutes and the time to succumb, ventilate, and stand upright were measured. There were 5 treatment groups with each one paired to a control group using saline injections: 1) octopamine (OA) and its antagonist epinastine (EP), 2) dopamine (DA) and its antagonist haloperidol, 3) serotonin (5‐HT) and its antagonist mianserin, 4) tyramine (TA) and its antagonist yohimbine, and 5) histamine (HA) and its antagonist pyrilamine maleate salt. Results indicated that EP‐injected locusts took significantly longer to succumb, ventilate, and stand upright compared to controls. Mianserin‐injected locusts also took significantly longer to succumb, ventilate, and stand upright.

Extracellular potassium in neuropile and nerve cell body region of the leech central nervous system

1980 ◽  
Vol 87 (1) ◽  
pp. 23-43
Author(s):  
W. R. Schlue ◽  
J. W. Deitmer
Keyword(s):  
Nerve Cell ◽  
Cell Body ◽  
Potassium Concentration ◽  
Rate Of Change ◽  
Body Region ◽  
Extracellular Potassium ◽  
Nerve Cell Body ◽  
Potassium Ions ◽  
Bathing Medium ◽  
Extracellular Potassium Concentration

Potassium-sensitive double-barrelled microelectrodes were used to measure the potassium content of extracellular spaces in leech ganglia, both intact and with the ganglion capsule opened. When the ganglion capsule was opened, the extracellular concentrations of potassium in the ganglion were similar to that of the bathing medium (4 mM). With intact ganglia the extracellular potassium concentration in the neuropile averaged 6.3 +/− 0.7 mM and in the nerve cell body region 5.8 +/− 0.6 mM. The potential measured in these parts of the ganglion was between +2 and −8 mV, averaging −1.9 mV. The change of potassium concentration in the extracellular spaces following increase or decrease in the concentration of potassium ions in the bath declined exponentially. This rate of change, which would be expected of a first-order diffusion process, was found in both the neuropile and the nerve cell body region. In a medium containing 5 × 10(−4) M ouabain, the potassium concentration in both parts of the ganglion increased transiently by an average of 3.8 +/− 1.0 mM in the neuropile and 1.2 +/− 0.4 mM in the nerve cell body region. Negatively charged polyelectrolytes in extracellular spaces of leech ganglia could affect the distribution of potassium ions to give a Donnan distribution. It is also possible, that the endothelial layer influences the extracellular potassium concentration in a ganglion under resting conditions.

scholarly journals Cell swelling increases the severity of spreading depression in Locusta migratoria

2015 ◽  
Vol 114 (6) ◽  
pp. 3111-3120 ◽  
Author(s):  
Kristin E. Spong ◽  
Brittany Chin ◽  
Kelsey L. M. Witiuk ◽  
R. Meldrum Robertson
Keyword(s):  
Spreading Depression ◽  
Locusta Migratoria ◽  
Cell Swelling ◽  
Extracellular Potassium ◽  
Potassium Ions ◽  
Extracellular Compartment ◽  
Propagating Waves ◽  
The Central Nervous System ◽  
Progressive Accumulation ◽  
Increased Susceptibility

Progressive accumulation of extracellular potassium ions can trigger propagating waves of spreading depression (SD), which are associated with dramatic increases in extracellular potassium levels ([K+]o) and arrest in neural activity. In the central nervous system the restricted nature of the extracellular compartment creates an environment that is vulnerable to disturbances in ionic homeostasis. Here we investigate how changes in the size of the extracellular space induced by alterations in extracellular osmolarity affect locust SD. We found that hypotonic exposure increased susceptibility to experimentally induced SD evidenced by a decrease in the latency to onset and period between individual events. Hypertonic exposure was observed to delay the onset of SD or prevent the occurrence altogether. Additionally, the magnitude of extracellular K+ concentration ([K+]o) disturbance during individual SD events was significantly greater and they were observed to propagate more quickly under hypotonic conditions compared with hypertonic conditions. Our results are consistent with a conclusion that hypotonic exposure reduced the size of the extracellular compartment by causing cell swelling and thus facilitated the accumulation of K+ ions. Lastly, we found that pharmacologically reducing the accumulation of extracellular K+ using the K+ channel blocker tetraethylammonium slowed the rate of SD propagation while increasing [K+]o through inhibition of the Na-K-2Cl cotransporter increased propagation rates. Overall our findings indicate that treatments or conditions that act to reduce the accumulation of extracellular K+ help to protect against the development of SD and attenuate the spread of ionic disturbance adding to the evidence that diffusion of K+ is a leading event during locust SD.

Intracellular potassium ion activity in resting and stimulated mouse pancreas and submandibular gland

1979 ◽  
Vol 204 (1154) ◽  
pp. 99-104 ◽  
Keyword(s):  
Submandibular Gland ◽  
Marked Decrease ◽  
Potassium Ion ◽  
Pancreatic Acinar Cells ◽  
Extracellular Potassium ◽  
Potassium Ions ◽  
Mouse Pancreas ◽  
Intracellular Potassium ◽  
Ion Activity ◽  
Ion Activities

Intracellular potassium ion activities ( a i K + ) and membrane potentials were measured with double-barrelled, potassium-specific microelectrodes in superfused mouse pancreas and submandibular gland. Stimulation with the cholinergic agonist bethanechol caused a marked decrease in a i K + in the submandibular gland, whereas no change in a i K + could be detected in the pancreas. This indicates that bethanechol increases the permeability of the cell membranes to potassium ions in the submandibular gland but not in the pancreas. Pancreatic acinar cells hyperpolarized promptly when the extracellular potassium ion activity was restored after a prolonged period of potassium deprivation. In comparison, the recovery of a i K + was a slow process. This finding gives support to the view that the hyperpolarization is due to electrogenic sodium pumping.

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