Light-scattering effects in the measurement of membrane microviscosity with diphenylhexatriene

Lentz, Barry R.; Moore, Bryant M.; Barrow, D.A.

doi:10.1016/s0006-3495(79)85318-7

Cited by 194 publications

(83 citation statements)

References 15 publications

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“…In this study, we examined the phospholipid (PS) translocation, membrane lipid package, membrane fluidity and anisotropy, cell size (shrinkage) and DNA fragmentation. We used EL4 cells -a lymphoma cell line known for its susceptibility to apoptosis [12][13][14][15][16][17][18][19]23].…”

Section: Discussionmentioning

confidence: 99%

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Kinetics of apoptotic markers in exogeneously induced apoptosis of EL4 cells

Jessel

Haertel

Socaciu

et al. 2002

J Cellular Molecular Medi

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We investigated the time‐dependence of apoptotic events in EL4 cells by monitoring plasma membrane changes in correlation to DNA fragmentation and cell shrinkage. We applied three apoptosis inducers (staurosporine, tubericidine and X‐rays) and we looked at various markers to follow the early‐to‐late apoptotic events: phospholipid translocation (identified through annexin V‐fluorescein assay and propidium iodide), lipid package (via merocyanine assay), membrane fluidity and anisotropy (via fluorescent measurements), DNA fragmentation by the fluorescence‐labeling test and cell size measurements. The different apoptotic inducers caused different reactions of the cells: staurosporine induced apoptosis most rapidly in a high number of cells, tubercidine triggered apoptosis only in the S phase cells, while X‐rays caused a G2/M arrest and subsequently apoptosis. Loss of lipid asymmetry is promptly detectable after one hour of incubation time. The phosphatidylserine translocation, decrease of lipid package and anisotropy, and the increase of membrane fluidity appeared to be based on the same process of lipid asymmetry loss. Therefore, the DNA fragmentation and the cell shrinkage appear to be parallel and independent processes running on different time scales but which are kinetically inter‐related. The results indicate different signal steps to apoptosis dependent on inducer characteristics but the kinetics of “early‐to‐late” apoptosis appears to be a fixed program.

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Section: Discussionmentioning

confidence: 99%

“…The stationary fluorescence anisotropy was calculated using the formula: r= (I ⊥ -I || / I || )+2 I ⊥ [15]. The fluorescence intensities were corrected for scattered light [16].…”

Section: Determination Of Plasma Membrane Fluiditymentioning

confidence: 99%

Kinetics of apoptotic markers in exogeneously induced apoptosis of EL4 cells

Jessel

Haertel

Socaciu

et al. 2002

J Cellular Molecular Medi

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“…In determination of polarization,, light scattering was reduced as described above. In addition, samples were serially diluted and polarization was measured and then extrapolated to zero absorbance [25,26]. The steady-state polarization, P, was corrected for excitation system-induced anisotropies [27].…”

Section: Fluorescence Spectroscopymentioning

confidence: 99%

Fluorescence properties of cholestatrienol in phosphatidylcholine bilayer vesicles

Schroeder

Nemecz

Gratton

et al. 1988

Biophysical Chemistry

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The fluorescent sterol A5~7~g*~")-cholestatrien-3&ol (cholestatrienol) was incorporated into l-pahnitoyl-2-oleoyl-phosphatidylcholine (POPC) small unilamellar vesicles (WV) with and without cholesterol in order to monitor sterol-sterol interactions in model membranes. Previously another fluorescent sterol, dehydroergosterol (F. Schroeder, Y. Barenholz, E. Gratton and T.E. Thompson, Biochemistry 26 (1987) 2441), was used for this purpose. However, there is some concern that dehydroergosterol may not be the best analogue for cholesterol. Fluorescence properties of cholestatrienol in POPC SW were highly sensitive to cholestatrienol purity. The fluorescence decay of cholestatienol in the POPC SUV was analyzed by assuming either that the decay is comprised of a discrete sum of exponential components or that the decay is made up of one or more component's distribution of lifetimes. The decay for cholestatrienol in POPC SUV analyzed using distributions had a lower x2 value and was described by a two-component Lorentzian function with centers near 0.86 and 3.24 ns, and fractional intensities of 0.96 and 0.04, respectively. Both distributions were quite narrow, i.e., 0.05 ns full-width at half-maximum peak height. It is proposed that the two lifetime distributions are generated by separate continua of environments for the cholestatrienol molecule described by different dielectric constants. In the range O-6 mol% cholestatrienol, the cholestatrienol underwent a concentration-dependent relaxation. This process was characterized by red-shifted absorption and maxima and altered ratios of absorption and fluorescence excitation maxima. Fluorescence quantum yield, lifetime, steady-state anisotropy, limiting anisotropy and rotational rate remained constant. In contrast, in POPC vesicles containing between 6 and 33 mol% cholestatrienol, the fluorescent cholestatrienol partially segregated, resulting in quenching. Thus, below 6 mot% cholestatienol, the cholestatrienol appeared to behave in part as monomers exposed to some degree to the aqueous solvent in a sterol-poor domain within POPC bilayers. Sin= the lifetime did not decrease above 6 molX cholestatrienol, the fluorescence at high mol% values of cholestatrienol was due to cholestatrienol in the sterol-poor domain. The fluorescence intensity, quantum yield, steady-state anisotropy, and limiting anisotropy of cholestatrienol in the sterol-poor domain decreased to limiting, nonzero values while the rotational rate increased to a limiting value. Thus, the sterol-poor domain became more disordered when it coexisted with the sterol-rich domain. In POPC vesicles containing 3 mol% cholestatrienol plus increasing mol% cholesterol the two sterols codistributed, since fluorescence quenching was not observed. Above 6 mol% total sterol the cholestatrienol was sensitive to sterol motional properties in the laterally segregated sterol-rich domain. The sterol-rich domain became more rigid with increasing cholesterol content of the POPC SUV. The data are consistent with the presence of a r...

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“…The excitation and emission wavelengths were 360 and 430 nm, respectively. Polarization (P) values were corrected for light scatter according to the method of Lentz et al (14). The polarization value of DPH fluorescence was used as a measure of membrane fluidity because increased anisotropy indicates a decrease of phospholipid acyl chain motion within the membrane (15).…”

Section: Membrane Fluiditymentioning

confidence: 99%

A Nuclear Receptor-mediated Choleretic Action of Fibrates is Associated with Enhanced Canalicular Membrane Fluidity and Transporter Activity Mediating Bile Acid-independent Bile Secretion

Nishioka

Hyogo

Numata

et al. 2005

JAT

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Fibrates are commonly used lipid-lowering agents that act via PPARα α α α α, a member of the nuclear hormone receptor superfamily. The mechanism(s) of fibrate-induced changes in the hepatic canalicular membrane and bile lipids are still unknown. Therefore, the aim of this study was to investigate the influence of fibrates on hepatic lipid metabolism and to assess the hepatocellular cytoprotective effect on hepatocyte canalicular membrane. Male ICR mice were fed standard chow with or without bezafibrate (100 mg/kg) for 6 days. The expression of canalicular membrane transporters (Mdr2 and Mrp2) was evaluated by RT-PCR and Western blotting. Canalicular membrane fluidity was also investigated. Canalicular membrane fluidity was markedly increased by fibrates. The expression of mdr 2 and mrp2 mRNA and protein showed a significant increase in fibrate-treated mice. These results suggested that fibrates improve liver function by enhancing bile secretion. The mechanism of the choleretic action of fibrate therapy might involve the enhancement of bile acid-independent bile secretion, since increased expression of Mdr2 and Mrp2 was found in fibrate-treated animals. These changes were very likely mediated by PPARα α α α α, and the increase of canalicular membrane fluidity may have been partly associated with enhancement of this transporter activity. J Atheroscler Thromb, 2005; 12: 211-217.

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Light-scattering effects in the measurement of membrane microviscosity with diphenylhexatriene

Cited by 194 publications

References 15 publications

Kinetics of apoptotic markers in exogeneously induced apoptosis of EL4 cells

Kinetics of apoptotic markers in exogeneously induced apoptosis of EL4 cells

Fluorescence properties of cholestatrienol in phosphatidylcholine bilayer vesicles

A Nuclear Receptor-mediated Choleretic Action of Fibrates is Associated with Enhanced Canalicular Membrane Fluidity and Transporter Activity Mediating Bile Acid-independent Bile Secretion

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