In vitro assessment of the effect of methylene blue on voltage-gated sodium channels and action potentials in rat hippocampal CA1 pyramidal neurons

2010 ◽  
Vol 31 (6) ◽  
pp. 724-729 ◽  
Author(s):  
Yinguo Zhang ◽  
Jingxia Zhao ◽  
Tao Zhang ◽  
Zhuo Yang
Keyword(s):  
Methylene Blue ◽  
Sodium Channels ◽  
Action Potentials ◽  
Pyramidal Neurons ◽  
Voltage Gated ◽  
Ca1 Pyramidal Neurons ◽  
Voltage Gated Sodium Channels ◽  
Hippocampal Ca1 ◽  
In Vitro Assessment

scholarly journals Sodium Channel Nav1.3 Is Expressed by Polymorphonuclear Neutrophils during Mouse Heart and Kidney Ischemia InVivo and Regulates Adhesion, Transmigration, and Chemotaxis of Human and Mouse Neutrophils In Vitro

2018 ◽  
Vol 128 (6) ◽  
pp. 1151-1166 ◽  
Author(s):  
Marit Poffers ◽  
Nathalie Bühne ◽  
Christine Herzog ◽  
Anja Thorenz ◽  
Rongjun Chen ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Sodium Channel ◽  
Sodium Channels ◽  
Polymorphonuclear Neutrophils ◽  
Human Neutrophils ◽  
Mouse Heart ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels

Abstract Background Voltage-gated sodium channels generate action potentials in excitable cells, but they have also been attributed noncanonical roles in nonexcitable cells. We hypothesize that voltage-gated sodium channels play a functional role during extravasation of neutrophils. Methods Expression of voltage-gated sodium channels was analyzed by polymerase chain reaction. Distribution of Nav1.3 was determined by immunofluorescence and flow cytometry in mouse models of ischemic heart and kidney injury. Adhesion, transmigration, and chemotaxis of neutrophils to endothelial cells and collagen were investigated with voltage-gated sodium channel inhibitors and lidocaine in vitro. Sodium currents were examined with a whole cell patch clamp. Results Mouse and human neutrophils express multiple voltage-gated sodium channels. Only Nav1.3 was detected in neutrophils recruited to ischemic mouse heart (25 ± 7%, n = 14) and kidney (19 ± 2%, n = 6) in vivo. Endothelial adhesion of mouse neutrophils was reduced by tetrodotoxin (56 ± 9%, unselective Nav-inhibitor), ICA121431 (53 ± 10%), and Pterinotoxin-2 (55 ± 9%; preferential inhibitors of Nav1.3, n = 10). Tetrodotoxin (56 ± 19%), ICA121431 (62 ± 22%), and Pterinotoxin-2 (59 ± 22%) reduced transmigration of human neutrophils through endothelial cells, and also prevented chemotactic migration (n = 60, 3 × 20 cells). Lidocaine reduced neutrophil adhesion to 60 ± 9% (n = 10) and transmigration to 54 ± 8% (n = 9). The effect of lidocaine was not increased by ICA121431 or Pterinotoxin-2. Conclusions Nav1.3 is expressed in neutrophils in vivo; regulates attachment, transmigration, and chemotaxis in vitro; and may serve as a relevant target for antiinflammatory effects of lidocaine.

scholarly journals Targeted Osmotic Lysis of Highly Invasive Breast Carcinomas Using Pulsed Magnetic Field Stimulation of Voltage-Gated Sodium Channels and Pharmacological Blockade of Sodium Pumps

Cancers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1420
Author(s):  
Dennis Paul ◽  
Paul Maggi ◽  
Fabio Del Piero ◽  
Steven D. Scahill ◽  
Kelly Jean Sherman ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Electrical Current ◽  
Normal Breast ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Reduce Tumor Growth ◽  
Osmotic Lysis ◽  
Stimulation Of

Concurrent activation of voltage-gated sodium channels (VGSCs) and blockade of Na+ pumps causes a targeted osmotic lysis (TOL) of carcinomas that over-express the VGSCs. Unfortunately, electrical current bypasses tumors or tumor sections because of the variable resistance of the extracellular microenvironment. This study assesses pulsed magnetic fields (PMFs) as a potential source for activating VGSCs to initiate TOL in vitro and in vivo as PMFs are unaffected by nonconductive tissues. In vitro, PMFs (0–80 mT, 10 msec pulses, 15 pps for 10 min) combined with digoxin-lysed (500 nM) MDA-MB-231 breast cancer cells stimulus-dependently. Untreated, stimulation-only, and digoxin-only control cells did not lyse. MCF-10a normal breast cells were also unaffected. MDA-MB-231 cells did not lyse in a Na+-free buffer. In vivo, 30 min of PMF stimulation of MDA-MB-231 xenografts in J/Nu mice or 4T1 homografts in BALB/c mice, concurrently treated with 7 mg/kg digoxin reduced tumor size by 60–100%. Kidney, spleen, skin and muscle from these animals were unaffected. Stimulation-only and digoxin-only controls were similar to untreated tumors. BALB/C mice with 4T1 homografts survived significantly longer than mice in the three control groups. The data presented is evidence that the PMFs to activate VGSCs in TOL provide sufficient energy to lyse highly malignant cells in vitro and to reduce tumor growth of highly malignant grafts and improve host survival in vivo, thus supporting targeted osmotic lysis of cancer as a possible method for treating late-stage carcinomas without compromising noncancerous tissues.

scholarly journals Membrane Dysfunction Induced by In Vitro Ischemia in Rat Hippocampal CA1 Pyramidal Neurons

1999 ◽  
Vol 81 (4) ◽  
pp. 1872-1880 ◽  
Author(s):  
E. Tanaka ◽  
S. Yamamoto ◽  
H. Inokuchi ◽  
T. Isagai ◽  
H. Higashi
Keyword(s):  
Membrane Potential ◽  
Voltage Clamp ◽  
Pyramidal Neurons ◽  
Membrane Surface ◽  
Bathing Medium ◽  
Ca1 Pyramidal Neurons ◽  
In Vitro Ischemia ◽  
Hippocampal Ca1 ◽  
Electrode Voltage

Membrane dysfunction induced by in vitro ischemia in rat hippocampal CA1 pyramidal neurons. Intracellular and single-electrode voltage-clamp recordings were made to investigate the process of membrane dysfunction induced by superfusion with oxygen and glucose-deprived (ischemia-simulating) medium in hippocampal CA1 pyramidal neurons of rat tissue slices. To assess correlation between potential change and membrane dysfunction, the recorded neurons were stained intracellularly with biocytin. A rapid depolarization was produced ∼6 min after starting superfusion with ischemia-simulating medium. When oxygen and glucose were reintroduced to the bathing medium immediately after generating the rapid depolarization, the membrane did not repolarize but depolarized further, the potential reaching 0 mV ∼5 min after the reintroduction. In single-electrode voltage-clamp recording, a corresponding rapid inward current was observed when the membrane potential was held at −70 mV. After the reintroduction of oxygen and glucose, the current induced by ischemia-simulating medium partially returned to preexposure levels. These results suggest that the membrane depolarization is involved with the membrane dysfunction. The morphological aspects of biocytin-stained neurons during ischemic exposure were not significantly different from control neurons before the rapid depolarization. On the other hand, small blebs were observed on the surface of the neuron within 0.5 min of generating the rapid depolarization, and blebs increased in size after 1 min. After 3 min, neurons became larger and swollen. The long and transverse axes and area of the cross-sectional cell body were increased significantly 1 and 3 min after the rapid depolarization. When Ca2+-free (0 mM) with Co2+ (2.5 mM)-containing medium including oxygen and glucose was applied within 1 min after the rapid depolarization, the membrane potential was restored completely to the preexposure level in the majority of neurons. In these neurons, the long axis was lengthened without any blebs being apparent on the membrane surface. These results suggest that the membrane dysfunction induced by in vitro ischemia may be due to a Ca2+-dependent process that commences ∼1.5 min after and is completed 3 min after the onset of the rapid depolarization. Because small blebs occurred immediately after the rapid depolarization and large blebs appeared 1.5–3 min after, it is likely that the transformation from small to large blebs may result in the observed irreversible membrane dysfunction.

Neuroprotective mechanisms of lidocaine against in vitro ischemic insult of the rat hippocampal CA1 pyramidal neurons

2005 ◽  
Vol 53 (3) ◽  
pp. 271-278 ◽  
Author(s):  
S. Niiyama ◽  
E. Tanaka ◽  
S. Tsuji ◽  
Y. Murai ◽  
M. Satani ◽  
...  
Keyword(s):  
Pyramidal Neurons ◽  
Ischemic Insult ◽  
Ca1 Pyramidal Neurons ◽  
Hippocampal Ca1

scholarly journals Voltage-gated sodium channels in neocortical pyramidal neurons display Cole-Moore activation kinetics

2017 ◽  
Author(s):  
Mara Almog ◽  
Tal Barkai ◽  
Angelika Lampert ◽  
Alon Korngreen
Keyword(s):  
Action Potential ◽  
Sodium Channels ◽  
Pyramidal Neurons ◽  
Brain Slices ◽  
Action Potential Generation ◽  
Potential Generation ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Gating Mechanism ◽  
Cortical Pyramidal Neurons

AbstractExploring the properties of action potentials is a crucial step towards a better understanding of the computational properties of single neurons and neural networks. The voltage-gated sodium channel is a key player in action potential generation. A comprehensive grasp of the gating mechanism of this channel can shed light on the biophysics of action potential generation. Most models of voltage-gated sodium channels assume it obeys a concerted Hodgkin and Huxley kinetic gating scheme. Here we performed high resolution voltage-clamp experiments from nucleated patches extracted from the soma of layer 5 (L5) cortical pyramidal neurons in rat brain slices. We show that the gating mechanism does not follow traditional Hodgkin and Huxley kinetics and that much of the channel voltage-dependence is probably due to rapid closed-closed transitions that lead to substantial onset latency reminiscent of the Cole-Moore effect observed in voltage-gated potassium conductances. This may have key implications for the role of sodium channels in synaptic integration and action potential generation.

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