Local mechanical oscillations of the cell surface within the range 0.2?30 Hz

Krol, Alexander; Grinfel'dt, M G; Levin, Shlomo; Smilgavichus, A. D.

doi:10.1007/bf00185092

Cited by 62 publications

(65 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The analysis of the time-dependent scattered light intensity was carried out in terms of normalized maximal amplitude of the scattered light intensity (⌬I max ͞I). A linear relationship between the normal maximal intensity amplitude of scattered light from a single illuminated area along the cell periphery and the amplitude of the cell's edge displacement was previously shown to exist over distances as long as 300 nm (⌬I max ͞I of Ϸ20%) (20). The accuracy of the experimental set-up was Ϸ1%.…”

Section: Methodsmentioning

confidence: 86%

“…2 ) at the cell edge and record cell membrane displacements by monitoring the time-dependent changes of light reflection and scattering, employing a home-made set-up of point dark field microscopy, similar to a previous report (20). The fluctuation of the light intensity depends on the changes of the membrane area moving in and out of the focused light spot near the cell's edge.…”

Section: Methodsmentioning

confidence: 96%

“…The measurement of local mechanical fluctuations of the cell membrane was carried out on RBC and RBC ghosts by a novel optical method based on point dark field microscopy (20,24). Using cells attached to a cover glass, we illuminate a very small area (0.25-1 m…”

Section: Methodsmentioning

confidence: 99%

“…CMF were recently observed in different types of nucleated cells (20)(21)(22)(23), suggesting that CMF are a common characteristic of the living cell. RBC plasma membrane and its underlying skeleton are relatively well characterized, making it an optimal cellular model system to study CMF.…”

mentioning

confidence: 95%

“…The CMF were monitored by point dark field microscopy (20)(21)(22)(23)(24), where a very small area (0.25 m 2 ) at the cell edge was illuminated and the time-dependent intensity changes of the reflected and scattered light due to cell membrane movement in and out of the focused light spot were recorded.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Cell membrane fluctuations are regulated by medium macroviscosity: Evidence for a metabolic driving force

Tuvia

Almagor

Bitler

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

115

View full text Add to dashboard Cite

Extracellular f luid macroviscosity (EFM), modified by macromolecular cosolvents as occurs in body f luids, has been shown to affect cell membrane protein activities but not isolated proteins. In search for the mechanism of this phenomenon, we examined the effect of EFM on mechanical f luctuations of the cell membrane of human erythrocytes. The macroviscosity of the external medium was varied by adding to it various macromolecules [dextrans (70, 500, and 2,000 kDa), polyethylene glycol (20 kDa), and carboxymethyl-cellulose (100 kDa)], which differ in size, chemical nature, and in their capacity to increase f luid viscosity. The parameters of cell membrane f luctuations (maximal amplitude and half-width of amplitude distribution) were diminished with the elevation of solvent macroviscosity, regardless of the cosolvent used to increase EFM. Because thermally driven membrane f luctuations cannot be damped by elevation of EFM, the existence of a metabolic driving force is suggested. This is supported by the finding that in ATPdepleted red blood cells elevation of EMF did not affect cell membrane f luctuations. This study demonstrates that (i) EFM is a regulator of membrane dynamics, providing a possible mechanism by which EFM affects cell membrane activities; and (ii) cell membrane f luctuations are driven by a metabolic driving force in addition to the thermal one.The viscosity of body fluids is determined by the level of macromolecules consisting of proteins, lipoproteins, and polysacharides (1). Accordingly, elevated plasma viscosity has been observed in various diseases associated with increased levels of proteins and lipoproteins, such as diabetes, hyperlipidemia, macroglobulinemia, multiple myeloma, nephrosis, and others (1-5). Various studies have shown that solvent viscosity affects protein dynamics and reactions (6-10). However, in these studies the solvent viscosity was modified by the addition of high concentrations of small cosolvents such as glycerol and sucrose, producing relatively high viscosity levels. This is incompatible with physiological and pathological states, where fluid viscosity is altered by small concentrations of large macromolecules (1). Other studies, in which the viscosity was elevated by macromolecular cosolvents, have shown that extracellular fluid macroviscosity (EFM) is a regulator of cellular processes, such as secretion of renin (11) and lipoproteins (12), phospholipase A 2 activity at the cell membrane (13, 14), and ganglioside metabolism (15). In search of the mechanism of this phenomenon, the effect of macroviscosity, as modified by macromolecules, on isolated proteins in aqueous solutions was examined (16,17). It was found that the effect of solvent viscosity decreases with increasing molecular weight of the cosolvent and is practically diminished when the cosolvent molecular weight exceeds that of the protein. Because the activity of cell membrane enzymes is known to be sensitive to the physical properties of the membrane (18), we considered the possibility that the...

show abstract

Section: Methodsmentioning

confidence: 86%

Section: Methodsmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 95%

mentioning

confidence: 99%

See 3 more Smart Citations