High salt mimics effects of light pulses on circadian pacemaker in cultured chick pineal cells

1991 ◽  
Vol 260 (4) ◽  
pp. R769-R776 ◽  
Author(s):  
M. Zatz ◽  
H. M. Wang
Keyword(s):  
Dominant Role ◽  
Red Light ◽  
Phase Shifts ◽  
Membrane Depolarization ◽  
Cell Swelling ◽  
Circadian Pacemaker ◽  
Cell Shrinkage ◽  
Phase Dependence ◽  
Melatonin Rhythm ◽  
High Concentrations

Chick pineal cells in static culture display a persistent photosensitive circadian rhythm of melatonin production and release. Pulses of white light or darkness, in otherwise constant red light, induce phase shifts in subsequent cycles whose magnitude and direction depend on the phase at which the pusle is given. Such "phase-dependent phase shifts" are mediated by effects on the underlying pacemaker. We reported previously that inhibiting the Na+-K+-adenosinetriphosphatase with ouabain evokes phase shifts with the same phase dependence as those induced by pulses of darkness. Two of the consequences of inhibiting the Na+ pump are membrane depolarization and cell swelling. To test the relevance of these effects and to distinguish between them, we exposed chick pineal cells to pulses of high concentrations of added KCl, which should cause both membrane depolarization and cell shrinkage. We also compared the effects of added NaCl, sodium gluconate, and mannitol, which should cause cell shrinkage without comparable depolarization. Each of these hypertonic solutions induced phase shifts in the melatonin rhythm with the same phase dependence as those caused by pulses of light rather than those caused by ouabain or darkness. These results argue strongly against a dominant role for changes in membrane potential in phase shifting the melatonin rhythm. Rather, they suggest that cell swelling may mediate the darklike effects of ouabain on the circadian pacemaker in chick pineal cells and indicate that cell shrinkage mimics the effects of light.

Low salt mimics effects of dark pulses on circadian pacemaker in cultured chick pineal cells

1991 ◽  
Vol 261 (6) ◽  
pp. R1424-R1430 ◽  
Author(s):  
M. Zatz ◽  
H. M. Wang
Keyword(s):  
Sodium Pump ◽  
Red Light ◽  
Phase Shifts ◽  
Phase Shifting ◽  
Cell Swelling ◽  
Circadian Pacemaker ◽  
Salt Solutions ◽  
Phase Dependence ◽  
Low Salt ◽  
Melatonin Production

Chick pineal cells in static culture display a persistent photosensitive circadian rhythm of melatonin production and release. Pulses of white light or darkness, in otherwise constant red light, induce phase shifts in subsequent cycles whose magnitude and direction depend on the phase at which the pulse is given. Such "phase-dependent phase shifts" are mediated by effects on the underlying pacemaker. We reported previously that inhibiting the Na-K-ATPase with ouabain or salt solutions lacking potassium evokes phase shifts with the same phase dependence as those induced by pulses of darkness. One of the consequences of inhibiting the sodium pump is cell swelling. To test the relevance of this effect, we exposed chick pineal cells to pulses of medium containing reduced concentrations of NaCl, which should cause cell swelling. These hypotonic solutions induced phase shifts in the melatonin rhythm with the same phase dependence as those caused by pulses of ouabain or darkness. The size of the phase shifts varied with degree of dilution, and phase shifting was prevented by replacement of NaCl. In view of previous results showing that hypertonic media mimicked the phase-shifting effects of light, these results suggest that cell swelling may mediate the darklike effects of ouabain on the circadian pacemaker in chick pineal cells.

Regulation of cell function by the cellular hydration state

1994 ◽  
Vol 267 (3) ◽  
pp. E343-E355 ◽  
Author(s):  
D. Haussinger ◽  
F. Lang ◽  
W. Gerok
Keyword(s):  
Cell Volume ◽  
Cell Function ◽  
Narrow Range ◽  
Cell Swelling ◽  
Metabolic Function ◽  
Cell Shrinkage ◽  
Short Term ◽  
Hydration State ◽  
Per Se ◽  
And Oxidative Stress

Cellular hydration can change within minutes under the influence of hormones, nutrients, and oxidative stress. Such short-term modulation of cell volume within a narrow range acts per se as a potent signal which modifies cellular metabolism and gene expression. It appears that cell swelling and cell shrinkage lead to certain opposite patterns of cellular metabolic function. Apparently, hormones and amino acids can trigger those patterns simply by altering cell volume. Thus alterations of cellular hydration may represent another important mechanism for metabolic control and act as another second or third messenger linking cell function to hormonal and environmental alterations.

Phase-advance shifts of human circadian pacemaker are accelerated by daytime physical exercise

2001 ◽  
Vol 281 (1) ◽  
pp. R197-R205 ◽  
Author(s):  
Toshihiko Miyazaki ◽  
Satoko Hashimoto ◽  
Satoru Masubuchi ◽  
Sato Honma ◽  
Ken-Ichi Honma
Keyword(s):  
Physical Exercise ◽  
Single Pulse ◽  
Time Of Day ◽  
Phase Advance ◽  
Circadian Pacemaker ◽  
Light Conditions ◽  
Melatonin Rhythm ◽  
Dim Light ◽  
The Difference ◽  
Isolation Facility

Effects of forced sleep-wake schedules with and without physical exercise were examined on the human circadian pacemaker under dim light conditions. Subjects spent 15 days in an isolation facility separately without knowing the time of day and followed a forced sleep-wake schedule of a 23 h 40-min period for 12 cycles, and physical exercise was imposed twice per waking period for 2 h each with bicycle- or rowing-type ergometers. As a result, plasma melatonin rhythm was significantly phase advanced with physical exercise, whereas it was not changed without exercise. The difference in phase was already significant 6 days after the start of exercise. The amplitude of melatonin rhythm was not affected. A single pulse of physical exercise in the afternoon or at midnight significantly phase delayed the melatonin rhythms when compared with the prepulse phase, but the amount of phase shift was not different from that observed in the sedentary controls. These findings indicate that physical exercise accelerates phase-advance shifts of the human circadian pacemaker associated with the forced sleep-wake schedule.

Volume-responsive sodium movements in dog red blood cells

1983 ◽  
Vol 244 (5) ◽  
pp. C324-C330 ◽  
Author(s):  
J. C. Parker
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Cell Swelling ◽  
Cell Shrinkage ◽  
Ph Change ◽  
Sodium Permeability ◽  
Sodium Gradient ◽  
Sodium Flux ◽  
Sodium Hydrogen Exchanger

As dog red blood cells are shrunken in vitro, their sodium permeability increases progressively. Some new features of this volume-responsive transport process are described. Retardation of sodium movements in shrunken cells occurs when chloride is replaced by the more conductive anions: nitrate or thiocyanate. Micromolar concentrations of amiloride or quinidine inhibit the increment of sodium flux associated with a reduction in cell volume. In the presence of a large outwardly directed sodium gradient, dog red blood cells can progressively alkalinize the medium in which they are suspended. This pH change is stimulated by cell shrinkage, reversed by cell swelling, retarded when chloride is replaced by nitrate or thiocyanate, and inhibited by micromolar concentrations of amiloride or quinidine. The similarities between the shrinkage-associated sodium flux and the alkalinization phenomenon suggest that the mechanism responsible for increased sodium permeability in shrunken cells can be made to operate as a sodium-hydrogen exchanger.

scholarly journals Photo-excited Toluidine Blue disaggregates the Repeat Tau and modulates cytoskeletal structure in neuronal cells

2020 ◽  
Author(s):  
Tushar Dubey ◽  
Nalini Vijay Gorantla ◽  
Subashchandrabose Chinnathambi
Keyword(s):  
Toluidine Blue ◽  
Neuronal Cells ◽  
Red Light ◽  
Microtubule Polymerization ◽  
Toxic Concentration ◽  
Significant Toxicity ◽  
Neuro2a Cells ◽  
High Concentrations ◽  
Novel Strategy ◽  
20 Nm

AbstractAlzheimer’s disease is a progressive neurological disorder characterized by the intracellular accumulation of Tau protein aggregates. Inhibition of protein aggregation by photo-excited dyes is emerging as novel strategy for the treatment of certain diseases. Toluidine Blue is a basic phenothiazine dye having potency of photo-excitation by irradiation with red light at 630±20 nm. In present work, we studied the effect of Toluidine Blue and photo-excited TB on aggregation of repeat Tau in-vitro using Thioflavin S fluorescence assay, SDS-PAGE and electron microscopy. Results show that TB efficiently inhabited the formation of higher order aggregates. Moreover, the photo-excited TB led to disaggregation of the mature repeat Tau fibrils. Further, studies on the effect of Toluidine blue on cell viability and cytoskeleton network of Neuro2acells show that TB was not toxic to neuronal cells at lower concentrations but at high concentrations (> 5 μM) both TB and photo-excited TB induced significant toxicity. Immunofluorescence studies on the cytoskeleton of Neuro2a cells show that Toluidine Blue and photo-excited Toluidine Blue treatment at non-toxic concentration of 0.5 μM stimulated formation of actin rich lamellipodia and filopodia structures. Tubulin networks were also differentially modulated after the treatment of Toluidine Blue and photo-excited Toluidine Blue. End Binding protein 1 (EB1) levels were observed to increase after Toluidine Blue and photo-excited Toluidine Blue treatment indicating the accelerated microtubule polymerization. The overall study suggested that Toluidine Blue inhibited the aggregation of soluble Tau and photo-excited Toluidine Blue disaggregated the pre-formed Tau filaments.

Studies of membrane fusion. III. Fusion of erythrocytes with polyethylene glycol

1979 ◽  
Vol 36 (1) ◽  
pp. 61-72
Author(s):  
S. Knutton
Keyword(s):  
Polyethylene Glycol ◽  
Cell Fusion ◽  
Close Contact ◽  
Freeze Fracture ◽  
Cell Swelling ◽  
Adjacent Cell ◽  
Cell Contact ◽  
Cell Agglutination ◽  
High Concentrations ◽  
Freeze Fracture Electron Microscopy

Freeze-fracture electron microscopy has been used to investigate the mechanism of polyethylene glycol-induced cell fusion. Interaction of cells with the high concentrations of polyethylene glycol required for cell fusion results in cell agglutination with large planar areas of very close contact between adjacent cell membranes. An aggregation of intramembrane particles into large patches at the sites of cell-cell contact accompanies cell agglutination. Fusion occurs following the removal of most of the PEG when cells only remain in close contact at small (approximately 0.1 micrometer diameter) plaques of smooth membrane resulting in cells connected by one (or more) small cytoplasmic connexions. Expansion to form spherical fused cells occurs by a process of cell swelling.

Volume-sensitive Ca influx and release from intracellular pools in gastric parietal cells

1992 ◽  
Vol 263 (3) ◽  
pp. C584-C589 ◽  
Author(s):  
P. A. Negulescu ◽  
B. Munck ◽  
T. E. Machen
Keyword(s):  
Image Processing ◽  
Cell Volume ◽  
Digital Image Processing ◽  
Parietal Cells ◽  
Cell Swelling ◽  
Cell Shrinkage ◽  
Gastric Glands ◽  
Intact Rabbit ◽  
Induced Changes ◽  
Gastric Parietal Cells

The effects of osmotically induced changes in cell volume on cytoplasmic free Ca (Cai) were studied in parietal cells from intact rabbit gastric glands using digital image processing of fura-2 fluorescence. In resting unstimulated cells, Cai was unaffected by either cell swelling or shrinking when osmolarity was varied between 200 and 400 mosM (isotonicity 290 mosM). However, when cells were swelled in a 165 mosM solution (55% tonicity), a biphasic Ca increased was observed. On average, Cai increased transiently from 80 to 218 nM before stabilizing at approximately 140 nM. The peak was due to release from intracellular pools because it was present in Ca-free solutions while the sustained elevation was dependent on external Ca. In carbachol-stimulated cells, Ca influx was most sensitive to cell shrinkage. For example, addition of 25 mM sucrose (108% tonicity) caused a 30% decrease in the sustained carbachol-stimulated Cai increase (plateau). In contrast, carbachol-stimulated cells were relatively insensitive to cell swelling, with a 30% decrease in tonicity causing only a 15% increase in the plateau. However, as in the unstimulated cells, extreme (55% tonicity) swelling caused additional increases in Cai levels. The carbachol-dependent effects of changes in cell volume on Cai could be mimicked by treating cells with thapsigargin, an inhibitor of Ca pumps of intracellular membranes that also has been shown to stimulate Ca entry. Thus, although extreme swelling conditions (55% tonicity) could elicit Cai increases in either the presence or absence of agonist, agonist was required to observe Cai decreases due to cell shrinkage.(ABSTRACT TRUNCATED AT 250 WORDS)

Agonist-induced cytoplasmic volume changes in cultured rabbit parietal cells

2000 ◽  
Vol 279 (1) ◽  
pp. G40-G48 ◽  
Author(s):  
Thorsten Sonnentag ◽  
Wolf-Kristian Siegel ◽  
Oliver Bachmann ◽  
Heidi Rossmann ◽  
Andreas Mack ◽  
...  
Keyword(s):  
Volume Regulation ◽  
Parietal Cells ◽  
Cell Swelling ◽  
Secretory Process ◽  
Cell Shrinkage ◽  
Rapid Loss ◽  
Volume Changes ◽  
Volume Increase ◽  
Regulatory Volume Increase ◽  
Stimulation Of

Concomitant Na+/H+ and Cl−/HCO3 − exchange activation occurs during stimulation of acid secretion in cultured rabbit parietal cells, possibly related to a necessity for volume regulation during the secretory process. We investigated whether cytoplasmic volume changes occur during secretagogue stimulation of cultured rabbit parietal cells. Cells were loaded with the fluorescent dye calcein, and the calcein concentration within a defined cytoplasmic volume was recorded by confocal microscopy. Forskolin at 10−5 M, carbachol at 10−4 M, and hyperosmolarity (400 mosmol) resulted in a rapid increase in the cytoplasmic dye concentration by 21 ± 6, 9 ± 4, and 23 ± 5%, respectively, indicative of cell shrinkage, followed by recovery to baseline within several minutes, indicative of regulatory volume increase (RVI). Depolarization by 5 mM barium resulted in a decrease of the cytoplasmic dye concentration by 10 ± 2%, indicative of cell swelling, with recovery within 15 min, and completely prevented forskolin- or carbachol-induced cytoplasmic shrinkage. Na+/H+ exchange inhibitors slightly reduced the initial cell shrinkage and significantly slowed the RVI, whereas 100 μM bumetanide had no significant effect on either parameter. We conclude that acid secretagoguges induce a rapid loss of parietal cell cytoplasmic volume, followed by RVI, which is predominantly mediated by Na+/H+ and Cl−/HCO3 − exchange.

Melatonin Rhythm Observed throughout a Three-Cycle Bright-Light Stimulus Designed to Reset the Human Circadian Pacemaker

1999 ◽  
Vol 14 (3) ◽  
pp. 237-253 ◽  
Author(s):  
Theresa L. Shanahan ◽  
Richard E. Kronauer ◽  
Jeanne F. Duffy ◽  
Gordon H. Williams ◽  
Charles A. Czeisler
Keyword(s):  
Light Stimulus ◽  
Bright Light ◽  
Circadian Pacemaker ◽  
Melatonin Rhythm

Regulation of intracellular pH in cardiac muscle during cell shrinkage and swelling in anisosmolar solutions

1994 ◽  
Vol 266 (2) ◽  
pp. H658-H669 ◽  
Author(s):  
D. W. Whalley ◽  
P. D. Hemsworth ◽  
H. H. Rasmussen
Keyword(s):  
Intracellular Ph ◽  
Buffer Capacity ◽  
Cardiac Contractility ◽  
Cell Swelling ◽  
Maximal Rate ◽  
Intracellular Acidosis ◽  
Cell Shrinkage ◽  
Shrinkage And Swelling ◽  
Hyperosmolar Solutions ◽  
Rate Of Recovery

The effect on intracellular pH (pHi) of exposure to solutions of progressively increasing osmolarity from 418 to 620 mosM and to hyposmolar solutions (240 mosM) was examined in guinea pig ventricular muscle using ion-selective microelectrodes. Exposure of tissue to 418 mosM Tyrode solution (100 mM sucrose added) produced an intracellular alkalosis of approximately 0.1 U, whereas exposure to 620 mosM solution (300 mM sucrose added) caused an intracellular acidosis of approximately 0.1 U. The maximal rate of recovery of pHi from acidosis induced by an NH4Cl prepulse increased progressively as extracellular osmolarity was raised from 310 to 620 mosM. This suggests that the acidosis observed at steady state in 620 mosM solution is not due to inhibition of the Na(+)-H+ exchanger. In the presence of 10 microM ryanodine, exposure to 620 mosM solution produced a sustained intracellular alkalosis. We suggest that the decrease in pHi during exposure to 620 mosM solution is due, at least in part, to the acidifying influence of Ca2+ release from the sarcoplasmic reticulum. This decrease in pHi is expected to contribute to the negative inotrop reported in studies of cardiac contractility in markedly hyperosmolar solutions. There was no change in pHi when tissue was exposed to hyposmolar solution. However, the maximal rate of recovery of pHi from acidosis was slower in hyposmolar than in isosmolar solution, despite a concomitant decrease in the intracellular buffer capacity. This suggests that osmotic cell swelling results in inhibition of the sarcolemmal Na(+)-H+ exchanger.

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