scholarly journals The mechanism of the NH4 ion oscillatory transport across the excitable cell membrane

2005 ◽  
pp. 5-19
Author(s):  
Cedomir Radenovic ◽  
Milos Beljanski ◽  
Georgij Maksimov ◽  
Aleksandar Kalauzi ◽  
Milan Drazic
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Transport Processes ◽  
Excitable Cell ◽  
Direct Dependence ◽  
Nh4cl Solution ◽  
Oscillatory Processes

This paper presents results on typical oscillations of the membrane potential induced by the excitation of the cell membrane by different concentrations of the NH4Cl solution. The existence of four classes of oscillations of the membrane potential and several different single and local impulses rhythmically occurring were determined. It is known that the oscillatory processes of the membrane potential are in direct dependence on oscillatory transport processes of NH4 and Cl ions across the excitable cell membrane. A hypothesis on a possible mechanism of oscillatory transport processes of NH4 and Cl ions across the excitable cell membrane is also presented.

scholarly journals Variable mechanisms of action of lithium during generating of membrane potential oscilations across the excitable membrane of the Nitela cell

2012 ◽  
pp. 101-114
Author(s):  
Cedomir Radenovic ◽  
Milos Beljanski ◽  
Georgij Maksimov ◽  
Dragomir Stanisavljev
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Mechanisms Of Action ◽  
Transport Processes ◽  
Excitable Membrane ◽  
Potential Oscillations ◽  
Excitable Cell ◽  
Lithium Transport ◽  
Membrane Potential Oscillations

This study presents results on variable mechanisms of lithium transport processes during generating of membrane potential oscillations across the very excitable membrane of the Nittela cell. Generating of several classes of oscillations, single and local impulses of the membrane potential, were presented in dependence on effects of a high LiCl concentration (10 mM), with which the cell membrane is very excited. Results on membrane potential oscillations are presented, and then some of oscillogram parameters were displayed. The assertion is that oscillations of the membrane potential are caused by total oscillatory transport processes: Li+, K+, Na+ and Cl-across the very excitable cell membrane. The paper presents the hypothesis on mechanisms of oscillatory transport processes of ions (Li, Na, K and Cl) expressed over different classes of oscillations, single and local impulses of the membrane potential across the excitable membrane of the Nittela cell.

Oxygen free radicals affect cardiac and skeletal cell membrane potential during hemorrhagic shock in rats

1992 ◽  
Vol 262 (1) ◽  
pp. H84-H90
Author(s):  
J. Yokota ◽  
J. J. Chiao ◽  
G. T. Shires
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Hemorrhagic Shock ◽  
Organ Blood Flow ◽  
Atp Content ◽  
Shed Blood ◽  
Excitable Cell ◽  
Significant Difference

Oxygen free radical (OFR) damage of excitable cell membranes (heart and skeletal muscle) during hemorrhagic shock and after resuscitation was studied in control rats and in rats pretreated with superoxide dismutase (SOD) and catalase (CAT; 6,000 U each) before hemorrhage. Their mean arterial pressure (MAP) was lowered to and maintained at 45 mmHg until 30% of the shed blood was spontaneously reinfused. The remaining blood and twice that volume of lactated Ringer solution were then infused. Cardiac output and organ blood flow were measured by the microsphere technique. The resting membrane potential (Em) and tissue ATP content in the heart and skeletal muscle were determined. There was no significant difference between the control and SOD + CAT groups in shock duration, maximal shed blood, hemodynamics, regional blood flow, or in ATP content in both heart and skeletal muscle, both during shock and after resuscitation. Radical scavenger treatment did not prevent muscle depolarization during shock. After resuscitation, however, significant repolarization in hearts and skeletal muscle of the SOD + CAT group (heart, -70.0 +/- 1.1; muscle, -87.0 +/- 0.6 mV) was noted when compared with the controls (heart, -62.5 +/- 1.2; muscle, -82.7 +/- 1.1 mV; P less than 0.05). This implicates OFRs as mediators of excitable cell membrane injury following resuscitation.

Electrophysiology of mammalian gland cells

1976 ◽  
Vol 56 (3) ◽  
pp. 535-577 ◽  
Author(s):  
O. H. Petersen
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Concentration Gradient ◽  
Gland Cell ◽  
Membrane Resistance ◽  
Transport Processes ◽  
Receptor Interaction ◽  
Cellular Transport ◽  
Gland Cells ◽  
Surface Cell

The resting cell membrane potential varies from -40 to -70 mV according to type of gland cell and species. The RP depends mainly on the large transmembrane concentration gradient for K maintained by a pump mechanism extruding Na and accumulating K. Since the Na permeability (PNa) is much smaller than PK, the Na concentration gradient is less important. In addition to the dominant electrodiffusional control of RP the Na pump itself contributes since the active transport of Na (out) exceeds that of the active K uptake. Gland cells are generally electrically coupled--i.e., the junctional membrane resistance is much lower than the surface membrane resistance. The coupling may be widespread (e.g., liver) or confined to one acinus (e.g., salivary gland and pancreas). The specific surface cell membrane resistance may be about 2000 omega cm2. A number of neurotransmitters and hormones control cellular transport processes by their action on surface cell membrane receptors. Agonist-receptor interaction causes prominent changes in membrane potential and resistance, in many cases of a complex nature. Most gland cell membranes so far investigated in detail appear to be electrically inexcitable; i.e., stimulation does not cause the appearance of action potentials (e.g., salivary glands, exocrine pancreas, and liver) but prominent exceptions to this are the endocrine pancreas (beta-cells) and the adrenal cortex. The main importance of agonist-induced membrane permeability changes is to alter the intracellular ion activities. An increase in [Na+] seems to be important whenever stimulation results in fluid transport and an increase in [Ca2+] triggers exocytosis.

Deposition of Polypyrrole Onto a Novel Polymer Electrode for Use in a Biomimetic Artificial Excitable Cell Membrane

2010 ◽  
Author(s):  
Christina V. Haden ◽  
Donald A. Jordan ◽  
Pamela M. Norris
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Membrane ◽  
Surface Morphology ◽  
Polymer Membrane ◽  
Electroactive Polymer ◽  
Gating System ◽  
Excitable Cell ◽  
Semi Solid ◽  
Scanning Electron

A novel and inexpensive bucky gel electrode has been investigated for use as the electrode substrate for deposition of polypyrrole. The electroactive polymer membrane was successfully deposited and the surface morphology studied using scanning electron microscopy. Given the properties of the bucky gel electrode and its ability to conduct ions, this work establishes the first step towards a semi-solid ion-gating system to be used in further applications.

scholarly journals Imaging the transmembrane and transendothelial sodium gradients in gliomas

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Muhammad H. Khan ◽  
John J. Walsh ◽  
Jelena M. Mihailović ◽  
Sandeep K. Mishra ◽  
Daniel Coman ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Magnetic Resonance ◽  
Cell Membrane ◽  
Normal Tissue ◽  
Magnetic Resonance Spectroscopic Imaging ◽  
Biological Factors ◽  
High Sodium ◽  
Intracellular Milieu

AbstractUnder normal conditions, high sodium (Na+) in extracellular (Na+e) and blood (Na+b) compartments and low Na+ in intracellular milieu (Na+i) produce strong transmembrane (ΔNa+mem) and weak transendothelial (ΔNa+end) gradients respectively, and these manifest the cell membrane potential (Vm) as well as blood–brain barrier (BBB) integrity. We developed a sodium (23Na) magnetic resonance spectroscopic imaging (MRSI) method using an intravenously-administered paramagnetic polyanionic agent to measure ΔNa+mem and ΔNa+end. In vitro 23Na-MRSI established that the 23Na signal is intensely shifted by the agent compared to other biological factors (e.g., pH and temperature). In vivo 23Na-MRSI showed Na+i remained unshifted and Na+b was more shifted than Na+e, and these together revealed weakened ΔNa+mem and enhanced ΔNa+end in rat gliomas (vs. normal tissue). Compared to normal tissue, RG2 and U87 tumors maintained weakened ΔNa+mem (i.e., depolarized Vm) implying an aggressive state for proliferation, whereas RG2 tumors displayed elevated ∆Na+end suggesting altered BBB integrity. We anticipate that 23Na-MRSI will allow biomedical explorations of perturbed Na+ homeostasis in vivo.

Pressure-induced smooth muscle cell depolarization in pulmonary arteries from control and chronically hypoxic rats does not cause myogenic vasoconstriction

2005 ◽  
Vol 98 (3) ◽  
pp. 1119-1124 ◽  
Author(s):  
Jay S. Naik ◽  
Scott Earley ◽  
Thomas C. Resta ◽  
Benjimen R. Walker
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Arteries ◽  
Barometric Pressure ◽  
Cell Membrane Potential ◽  
Intraluminal Pressure ◽  
Dose Dependent

Chronic obstructive pulmonary diseases, as well as prolonged residence at high altitude, can result in generalized airway hypoxia, eliciting an increase in pulmonary vascular resistance. We hypothesized that a portion of the elevated pulmonary vascular resistance following chronic hypoxia (CH) is due to the development of myogenic tone. Isolated, pressurized small pulmonary arteries from control (barometric pressure ≅ 630 Torr) and CH (4 wk, barometric pressure = 380 Torr) rats were loaded with fura 2-AM and perfused with warm (37°C), aerated (21% O2-6% CO2-balance N2) physiological saline solution. Vascular smooth muscle (VSM) intracellular Ca2+ concentration ([Ca2+]i) and diameter responses to increasing intraluminal pressure were determined. Diameter and VSM cell [Ca2+]i responses to KCl were also determined. In a separate set of experiments, VSM cell membrane potential responses to increasing luminal pressure were determined in arteries from control and CH rats. VSM cell membrane potential in arteries from CH animals was depolarized relative to control at each pressure step. VSM cells from both groups exhibited a further depolarization in response to step increases in intraluminal pressure. However, arteries from both control and CH rats distended passively to increasing intraluminal pressure, and VSM cell [Ca2+]i was not affected. KCl elicited a dose-dependent vasoconstriction that was nearly identical between control and CH groups. Whereas KCl administration resulted in a dose-dependent increase in VSM cell [Ca2+]i in arteries taken from control animals, this stimulus elicited only a slight increase in VSM cell [Ca2+]i in arteries from CH animals. We conclude that the pulmonary circulation of the rat does not demonstrate pressure-induced vasoconstriction.

Pancreatic beta-cell electrical activity: the role of anions and the control of pH

1983 ◽  
Vol 244 (3) ◽  
pp. C188-C197 ◽  
Author(s):  
G. T. Eddlestone ◽  
P. M. Beigelman
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Beta Cell ◽  
Pancreatic Beta Cell ◽  
Proton Exchange ◽  
Disulfonic Acid ◽  
Control Mechanisms ◽  
Exchange System ◽  
Sodium Proton Exchange

The influence of chloride on the mouse pancreatic beta-cell membrane potential and the cell membrane mechanisms controlling intracellular pH (pHi) have been investigated using glass microelectrodes to monitor the membrane potential. It has been shown that chloride is distributed passively across the beta-cell membrane such that chloride potential is equal to the membrane potential. Withdrawal of perifusate chloride or bicarbonate and the application of the drugs 4-acetamido-4'-isethiocyanostilbene-2,2'-disulfonic acid (SITS) and probenecid, both blockers of transmembrane anion movement, have been used to establish that a chloride-bicarbonate exchange system is operative in the cell membrane and that it is one of the control mechanisms of pHi. Amiloride, a specific blocker of the transmembrane sodium proton exchange, has been used to demonstrate that this mechanism is also operative in the beta-cell membrane in the control of pHi. The hypothesis that the calcium-activated potassium permeability is proton sensitive at an intracellular site, a fall in pHi causing a fall in permeability and an increase in pHi causing an increase in permeability, has been used to explain many of the effects observed in this study.

Sign in / Sign up

Export Citation Format

Share Document