The transmembrane gradient of osmotic pressure modifies the kinetics of sodium currents in perfused neurons

1983 ◽  
Vol 39 (5) ◽  
pp. 494-495 ◽  
Author(s):  
O. A. Krishtal ◽  
Yu. V. Osipchuk ◽  
V. I. Pidoplichko
Keyword(s):  
Osmotic Pressure ◽  
Sodium Currents ◽  
Kinetics Of

scholarly journals THE KINETICS OF EXOSMOSIS OF WATER FROM LIVING CELLS

1927 ◽  
Vol 10 (5) ◽  
pp. 659-664 ◽  
Author(s):  
Morton McCutcheon ◽  
Baldwin Lucke
Keyword(s):  
Osmotic Pressure ◽  
Salt Concentration ◽  
Driving Force ◽  
Temperature Characteristic ◽  
Living Cells ◽  
Velocity Constant ◽  
Osmotic Equilibrium ◽  
Kinetics Of

1. The rate of exosmosis of water was studied in unfertilized Arbacia eggs, in order to bring out possible differences between the kinetics of exosmosis and endosmosis. 2. Exosmosis, like endosmosis, is found to follow the equation See PDF for Equation, in which a is the total volume of water that will leave the cell before osmotic equilibrium is attained, x is the volume that has already left the cell at time t, and k is the velocity constant. 3. The velocity constants of the two processes are equal, provided the salt concentration of the medium is the same. 4. The temperature characteristic of exosmosis, as of endomosis, is high. 5. It is concluded that the kinetics of exosmosis and endosmosis of water in these cells are identical, the only difference in the processes being in the direction of the driving force of osmotic pressure.

scholarly journals THE KINETICS OF OSMOSIS

1927 ◽  
Vol 10 (6) ◽  
pp. 883-892 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Osmotic Pressure ◽  
Egg Albumin ◽  
Kinetics Of

It is shown that by combining the osmotic pressure and rate of diffusion laws an equation can be derived for the kinetics of osmosis. The equation has been found to agree with experiments on the rate of osmosis for egg albumin and gelatin solutions with collodion membranes.

scholarly journals THE KINETICS OF PENETRATION

1938 ◽  
Vol 22 (2) ◽  
pp. 147-163 ◽  
Author(s):  
A. G. Jacques
Keyword(s):  
Osmotic Pressure ◽  
Free Space ◽  
Partition Coefficients ◽  
Sea Water ◽  
Intact Cell ◽  
Linear Part ◽  
Osmotic Concentration ◽  
Intact Cells ◽  
Rate Of Increase ◽  
Kinetics Of

When Valonia cells are impaled on capillaries, it is in some ways equivalent to removing the comparatively inelastic cellulose wall. Under these conditions sap can migrate into a free space and it is found that on the average the rate of increase of volume of the sap is 15 times what it is in intact cells kept under comparable conditions. The rate of increase of volume is a little faster during the first few hours of the experiment, but it soon becomes approximately linear and remains so as long as the experiment is continued. The slightly faster rate at first may mean that the osmotic pressure of the sap is approaching that of the sea water (in the intact cell the sap osmotic pressure is always slightly above that of the sea water). This might result from a more rapid entrance of water than of electrolyte, as would be expected when the restriction of the cellulose wall was removed. During the linear part of the curve the osmotic concentration and the composition of the sap suffer no change, so that entrance of electrolyte must be 15 times as fast in the impaled cells as it is in the intact cells. The explanation which best accords with the facts is that in the intact cell the entrance of electrolyte tends to increase the osmotic pressure. As a consequence the protoplasm is partially dehydrated temporarily and it cannot take up more water until the cellulose wall grows so that it can enclose more volume. The dehydration of the protoplasm may have the effect of making the non-aqueous protoplasm less permeable to electrolytes by reducing the diffusion and partition coefficients on which the rate of entrance depends. In this way the cell is protected against great fluctuations in the osmotic concentration of the sap.

scholarly journals FURTHER STUDIES ON THE KINETICS OF OSMOSIS IN LIVING CELLS

1931 ◽  
Vol 14 (3) ◽  
pp. 405-419 ◽  
Author(s):  
Balduin Lucké ◽  
H. Keffer Hartline ◽  
Morton McCutcheon
Keyword(s):  
Cell Surface ◽  
Osmotic Pressure ◽  
Volume Change ◽  
Living Cells ◽  
Arbacia Punctulata ◽  
Kinetics Of ◽  
And Diffusion ◽  
Swelling And Shrinking

Using unfertilized eggs of Arbacia punctulata as natural osmometers an attempt has been made to account for the course of swelling and shrinking of these cells in anisotonic solutions by means of the laws governing osmosis and diffusion. The method employed has been to compute permeability of the cell to water, as measured by the rate of volume change per unit of cell surface per unit of osmotic pressure outstanding between the cell and its medium. Permeability to water as here defined and as somewhat differently defined by Northrop is approximately constant during swelling and shrinking, at least for the first several minutes of these processes. Permeability is found to be independent of the osmotic pressure of the solution in which cells are swelling. Water is found to leave cells more readily than it enters, that is, permeability is greater during exosmosis than during endosmosis.

scholarly journals Sieving and reflection coefficients for sodium salts and glucose during peritoneal dialysis in rats.

1991 ◽  
Vol 2 (6) ◽  
pp. 1092-1100
Author(s):  
T W Chen ◽  
R Khanna ◽  
H Moore ◽  
Z J Twardowski ◽  
K D Nolph
Keyword(s):  
Peritoneal Dialysis ◽  
Osmotic Pressure ◽  
Peritoneal Cavity ◽  
Pressure Gradients ◽  
Peritoneal Membrane ◽  
Rat Serum ◽  
Cycle Times ◽  
Dialysis Solution ◽  
Kinetics Of ◽  
Sodium Sieving

The two-part studies reported herein address peritoneal membrane ultrafiltrate (UF) characteristics during peritoneal dialysis exchanges in rats. In the studies of part 1, the sieving coefficients for sodium, chloride, and total solutes during hydrostatic UF after instillation of rat serum into the peritoneal cavity of rats were calculated. Thirty-six rats were divided into six groups (N = 6) according to the following peritoneal dialysis exchange cycle times: 60, 120, 180, 240, 480, and 960 min. Thirty milliliters of pooled rat serum were infused i.p. with the animal being conscious except during infusion and drainage. The study showed in the early phase of exchanges, when oncotic and osmotic pressure gradients were absent, net UF presumably due to capillary hydrostatic pressure and sodium sieving during such UF. Sieving coefficients for sodium (0.72), chloride (0.77) and total solutes (0.73) were determined by using standard formulae. In the second part of these studies, the kinetics of fluid movement after the instillation of 5% dextrose solution into the peritoneal cavity of rats were analyzed. A very low UF rate was observed early in the exchange when the glucose gradient between the dialysis solution and blood was at its peak. The UF rate gradually increased as the sodium entered the dialysis solution from the blood. At the time of low UF rate with high glucose gradient, presumably the osmotic pressure generated by the glucose in the dialysis solution was countered by the osmotic pressure of solutes in plasma, i.e., sodium and its anions.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Tonic and phasic block of neuronal sodium currents by 5-hydroxyhexano-2',6'-xylide, a neutral lidocaine homologue.

1989 ◽  
Vol 93 (6) ◽  
pp. 1075-1090 ◽  
Author(s):  
D M Chernoff ◽  
G R Strichartz
Keyword(s):  
Rate Constant ◽  
Apparent Rate Constant ◽  
Sodium Current ◽  
Nerve Fibers ◽  
Sodium Currents ◽  
Net Charge ◽  
Single Receptor ◽  
Phasic Block ◽  
Affinity Model ◽  
Kinetics Of

The effects of a neutral lidocaine homologue, 5-hydroxyhexano-2',6'-xylidide (5-HHX), on the kinetics and amplitude of sodium currents in voltage-clamped amphibian nerve fibers are described. 5-HHX produced two types of sodium current inhibition: (a) tonic block, in resting fibers (IC50 approximately 2 mM), and (b) phasic block, an additional, incremental inhibition, in repetitively depolarized fibers (frequency greater than 1 Hz). The kinetics of phasic block were characterized by a single-receptor, switched-affinity model, in which binding increases during a depolarizing pulse and decreases between pulses. In the presence of 4 mM 5-HHX, binding increased during pulses from -80 to 0 mV, with an apparent rate constant of 6.4 +/- 1.4 s-1. Binding decreased between pulses with an apparent rate constant of 1.1 +/- 0.3 s-1. There was little effect of extracellular pH on the kinetics of phasic block. These findings demonstrate that neither the presence of a terminal amine nor a net charge on a local anesthetic is required for phasic block of sodium channels.

scholarly journals STUDIES ON OSMOTIC EQUILIBRIUM AND ON THE KINETICS OF OSMOSIS IN LIVING CELLS BY A DIFFRACTION METHOD

1935 ◽  
Vol 19 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Balduin Lucké ◽  
Martin G. Larrabee ◽  
H. Keffer Hartline
Keyword(s):  
Cell Surface ◽  
Osmotic Pressure ◽  
Diffraction Pattern ◽  
Monochromatic Light ◽  
Diffraction Method ◽  
Living Cells ◽  
Individual Variability ◽  
Concentration Difference ◽  
Osmotic Equilibrium ◽  
Kinetics Of

1. Osmotic equilibrium and kinetics of osmosis of living cells (unfertilized eggs of Arbacia punctulata) have been studied by a diffraction method. This method consists of illuminating a suspension of cells by parallel monochromatic light and measuring, by means of telescope and scale, the angular dimensions of the resulting diffraction pattern from which the average volume of the cells may be computed. The method is far less laborious and possesses several advantages over direct measurement of individual cells. The average size of a large number of cells is obtained from a single measurement of the diffraction pattern and thus individual variability is averaged out. The observations can be made at intervals of a few seconds, permitting changes in volume to be followed satisfactorily. During the measurements the cells are in suspension and are constantly stirred. 2. Volumes of cells in equilibrium with solutions of different osmotic pressure have been determined. In agreement with our previous experiments, based upon direct microscope measurements, we have confirmed the applicability of the law of Boyle-van't Hoff to these cells; that is to say, the product of volume and pressure has been found to be approximately constant if allowance be made for the volume of osmotically inactive material of the cell contents. The volume of osmotically inactive material was found to be, on the average, 12 per cent of the initial cell volume; in eggs from different animals this value ranged from 6 to 20 per cent. 3. Permeability to water of the Arbacia egg has been found to average, at 22°C., 0.106 cubic micra of water per square micron of cell surface, per minute, per atmosphere of difference in osmotic pressure. 4. Permeability to ethylene glycol has been found to average, at 24°C., 4.0 x 10–15 mols, per square micron of cell surface, per minute, for a concentration difference of 1 mol per liter. This is in agreement with the values reported by Stewart and Jacobs.

Tetrodotoxin-sensitive sodium current in native Xenopus oocytes

1987 ◽  
Vol 232 (1268) ◽  
pp. 289-296 ◽  
Keyword(s):  
Xenopus Laevis ◽  
Sodium Channels ◽  
Xenopus Oocytes ◽  
Sodium Current ◽  
Messenger Rnas ◽  
Sodium Currents ◽  
Inward Current ◽  
Calcium Dependent ◽  
Genes Encoding ◽  
Kinetics Of

Depolarization of oocytes of Xenopus laevis usually elicits mainly passive currents, and a calcium-dependent chloride current. However, oocytes obtained from some donors show, in addition, a transient inward current on depolarization to potentials beyond ca . –40 mV. This current is abolished by tetrodotoxin at submicromolar concentrations, and is prolonged by veratrine; thus, it probably arises through sodium channels of a type similar to those found in nerve and muscle cells. However, the kinetics of the sodium currents varied between oocytes from different donors; this result suggests that genes encoding different sodium channels may be expressed in oocytes from different donors. The presence of these native channels may complicate experiments to study the expression of exogenous sodium channels encoded by foreign messenger RNAs injected into the ooctye.

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