Abstract:
:Intracellular Ca2+ was determined with the fura-2 technique during electrically induced contractions in the rabbit rectococcygeus smooth muscle at 22 degreesC. The muscles were electrically activated to give short, reproducible contractions. Intracellular [Ca2+] increased during activation; the increase in [Ca2+] preceded force development by approximately 2 s. After cessation of stimulation Ca2+ fell, preceding the fall in force by approximately 4 s. The fluorescence properties of fura-2 were determined with time-resolved spectroscopy using synchrotron light at the MAX-storage ring, Lund, Sweden. The fluorescence decay of free fura-2 was best described by two exponential decays (time constants approximately 0.5 and 1.5 ns) at low Ca2+ (pCa 9). At high Ca2+ (pCa 4.5), fluorescence decay became slower and could be fitted by one exponential decay (1.9 ns). Time-resolved anisotropy of free fura-2 was characteristic of free rotational motion (correlation time 0.3 ns). Motion of fura-2 could be markedly inhibited by high concentrations of creatine kinase. Time-resolved spectroscopy measurements of muscle fibers loaded with fura-2 showed that the fluorescence lifetime of the probe was longer, suggesting an influence of the chemical environment. Anisotropy measurements revealed, however, that the probe was mobile in the cells. The Ca2+-dependence of contraction and relaxation was studied using a photolabile calcium chelator, diazo-2, which could be loaded into the muscle cells in a similar manner as fura-2. Photolysis of diazo-2 leads to an increase in its Ca2+-affinity and a fall in free Ca2+. When muscles that had been loaded with diazo-2 were illuminated with UV light flashes during the rising phase of contraction, the rate of contraction became slower, suggesting a close relation between intracellular Ca2+ and the cross-bridge interaction. In contrast, photolysis during relaxation did not influence the rate of force decay, suggesting that relaxation of these contractions is not determined by the rate of Ca2+ removal or due to an increased Ca2+ sensitivity, but instead is limited by other processes such as deactivation by dephosphorylation or detachment of tension-bearing cross-bridges, possibly regulated by thin filament systems.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Arner A,Malmqvist U,Rigler Rdoi
10.1016/S0006-3495(98)77630-1subject
Has Abstractpub_date
1998-10-01 00:00:00pages
1895-903issue
4eissn
0006-3495issn
1542-0086pii
S0006-3495(98)77630-1journal_volume
75pub_type
杂志文章abstract::In this study maximum shortening velocity (Vmax) and isometric tension (P0) in skinned single fibers from rat slow soleus (SOL) and fast superficial vastus lateralis (SVL) muscles were examined after varying degrees of filament lattice compression with dextran. In both fiber types Vmax was greatest in the absence of d...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(87)83197-1
更新日期:1987-07-01 00:00:00
abstract::The effects of cholesterol (Chol) on phospholipid bilayers include ordering of the fatty acyl chains, condensing of the lipids in the bilayer plane, and promotion of the liquid-ordered phase. These effects depend on the type of phospholipids in the bilayer and are determined by the nature of the underlying molecular i...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.106.088427
更新日期:2007-02-15 00:00:00
abstract::Determining the spatial relationship of individual proteins in dense assemblies remains a challenge for superresolution nanoscopy. The organization of aquaporin-4 (AQP4) into large plasma membrane assemblies provides an opportunity to image membrane-bound AQP4 antibodies (AQP4-IgG) and evaluate changes in their spatia...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2017.03.012
更新日期:2017-04-25 00:00:00
abstract::The intracellular and interstitial potentials associated with each cell or fiber in multicellular preparations carrying a uniformly propagating wave are important for characterizing the electrophysiological behavior of the preparation and in particular, for evaluating the source contributed by each fiber. The aforemen...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(88)83172-2
更新日期:1988-06-01 00:00:00
abstract::Singlet-singlet annihilation experiments have been performed on trimeric and aggregated light-harvesting complex II (LHCII) using picosecond spectroscopy to study spatial equilibration times in LHCII preparations, complementing the large amount of data on spectral equilibration available in literature. The annihilatio...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(01)76210-8
更新日期:2001-05-01 00:00:00
abstract::Plant light-harvesting complex II (LHCII) is the key antenna complex for plant photosynthesis. We present coarse-grained molecular dynamics simulations of monomeric and trimeric LHCII in a realistic thylakoid membrane environment based on the Martini force field. The coarse-grained protein model has been optimized wit...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2019.03.009
更新日期:2019-04-23 00:00:00
abstract::Several hundred solid state NMR dipolar couplings and chemical shift anisotropies were simulated for the polytopic membrane protein, bacteriorhodopsin, and for an idealized transmembrane peptide conforming to several different secondary structures (alpha- and 3(10)-helices and parallel and antiparallel beta-sheets), e...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(93)81215-3
更新日期:1993-10-01 00:00:00
abstract::During inflammation, flowing leukocytes tether to and roll on vascular surfaces through the association and dissociation of selectin/ligand bonds. The interactions of P- and L- selectins with their respective ligands exhibit catch-slip bonds, such that increasing force initially prolongs and then shortens bond lifetim...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.05.040
更新日期:2010-08-09 00:00:00
abstract::The atomic force microscopy (AFM) indentation method combined with the brush model can be used to separate the mechanical response of the cell body from deformation of the pericellular layer surrounding biological cells. Although self-consistency of the brush model to derive the elastic modulus of the cell body has be...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2016.06.005
更新日期:2016-07-12 00:00:00
abstract::Microorganisms often form complex multicellular assemblies such as biofilms and colonies. Understanding the interplay between assembly expansion, metabolic yield, and nutrient diffusion within a freely growing colony remains a challenge. Most available data on microorganisms are from planktonic cultures, due to the la...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2014.02.040
更新日期:2014-05-20 00:00:00
abstract::Changes in free energy are normally used to track the effect of temperature on the stability of proteins and hydrophobic interactions. Use of this procedure on the aqueous solubility of hydrocarbons, a standard representation of the hydrophobic effect, leads to the conclusion that the hydrophobic effect increases in s...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(97)78324-3
更新日期:1997-12-01 00:00:00
abstract::Phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) are the main lipid components of the inner bacterial membrane. A computer model for such a membrane was built of palmitoyloleoyl PE (POPE) and palmitoyloleoyl PG (POPG) in the proportion 3:1, and sodium ions (Na+) to neutralize the net negative charge on each...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.104.048835
更新日期:2005-02-01 00:00:00
abstract::The structural basis of the wide variability of the physical properties of fibrin clots and the process of assembly of the clot were investigated by electron microscopy of fibers formed under various ionic conditions. In addition, highly specific proteolytic enzymes from different snake venoms were used to remove sele...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(86)83552-4
更新日期:1986-12-01 00:00:00
abstract::This paper reports on a coupled approach to determining the structure of the gramicidin A ion channel, utilizing solid state nuclear magnetic resonance (NMR) of isotopically labeled gramicidin channels aligned parallel to the magnetic field direction, and molecular dynamics (MD). MD computations using an idealized rig...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(91)82131-2
更新日期:1991-10-01 00:00:00
abstract::Both the solution and the oriented film absorption and circular dichroic spectra of the bacteriorhodopsin (bR(568)) and M(412) intermediate of the purple membrane photocycle were compared over the wavelength region 800-183 nm to assess structural changes during this photocycle. The main findings are (a) loss of the ex...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(85)83943-6
更新日期:1985-04-01 00:00:00
abstract::TWIK-1 two-pore domain K(+) channels generally produce nonmeasurable or very low levels of K(+) currents in heterologous expression systems under physiologically ionic conditions. Two controversial mechanisms have been proposed to account for this behavior: TWIK-1 K(+) channels are expressed in the cell surface but si...
journal_title:Biophysical journal
pub_type: 信件
doi:10.1016/j.bpj.2012.03.011
更新日期:2012-04-18 00:00:00
abstract::We demonstrate the ability of pulsed dipolar electron spin resonance (ESR) spectroscopy (PDS) to report on the conformation of Cu-Zn superoxide dismutase (SOD1) through the sensitive measurement of dipolar interactions between inherent Cu(2+) ions. Although the extent and the anisotropy of the Cu ESR spectrum provides...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2014.07.068
更新日期:2014-10-07 00:00:00
abstract::NMR and CD studies have been used to analyze the model membrane-bound structure of the neuropeptide substance P (RPKPQQFFGLM-NH2, SP), which has previously been proposed as the NK1 receptor active form. Conformations were determined for the SP in the presence of aqueous solutions of zwitterionic dodecylphosphocholine ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(96)79734-5
更新日期:1996-04-01 00:00:00
abstract::Most of the cellular ATP in living organisms is synthesized by the enzyme F(1)F(o)-ATP synthase. The water soluble F(1) part of the enzyme can also work in reverse and utilize the chemical energy released during ATP hydrolysis to generate mechanical motion. Despite the availability of a large amount of biochemical dat...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(03)74650-5
更新日期:2003-10-01 00:00:00
abstract::Many traditional approaches to the analysis of sedimentation velocity data work poorly with data for low-molecular-weight solutes, which have sedimentation boundaries that are severely broadened by diffusion. An approach that has previously had some success is to directly fit these broad boundaries to approximate solu...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(97)78684-3
更新日期:1997-01-01 00:00:00
abstract::The general formalism required to treat two-state sliding filament models of muscle contraction, including free energy considerations, is first reviewed and amplified. This formalism is then used to examine, and modify as needed, three models studied previously by Podolsky and Nolan, in which cross-bridge attachment-d...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(75)85823-1
更新日期:1975-04-01 00:00:00
abstract::The hyperpolarization-activated cyclic nucleotide-modulated (HCN) cation channels are opened by membrane hyperpolarization, while their activation is modulated by the binding of cyclic adenosine monophosphate (cAMP) in the cytoplasm. Here we investigate the molecular basis of cAMP channel modulation by performing mole...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.105.071621
更新日期:2006-05-15 00:00:00
abstract::A detailed electron spin resonance (ESR) study of mixtures of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and phosphatidylserine (POPS) in oriented multilayers in the liquid crystalline phase is reported with the purpose of characterizing the effects of headgroup mixing on the structural and dynamical properties o...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(94)80942-7
更新日期:1994-05-01 00:00:00
abstract::A kinetic model of the effect of agonist and anesthetics on ligand-gated ion channels, developed in earlier work, is further refined and used to predict traces observed in fast-perfusion electrophysiological studies on recombinant GABAA receptors under a wide range of agonist and/or anesthetic concentrations. The mode...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2014.12.052
更新日期:2015-03-10 00:00:00
abstract::Multiconformation membrane proteins are mechanosensitive (MS) if their conformations displace different bilayer areas. Might MS closed-closed transitions serve as tension buffers, that is, as membrane "spandex"? While bilayer expansion is effectively instantaneous, transitions of bilayer-embedded MS proteins are stoch...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2009.08.054
更新日期:2009-11-18 00:00:00
abstract::Profiles of negatively stained gap junctions have been measured by grid sectioning. After normal levels of electron irradiation, the membrane thickness shrinks to about half that of unirradiated controls, but no shrinkage occurs in the hexagonal lattice plane. Even under low irradiation conditions, there is significan...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(88)83152-7
更新日期:1988-05-01 00:00:00
abstract::Skeletal muscle contraction is a canonical example of motor-driven force generation. Despite the long history of research in this topic, a mechanistic explanation of the collective myosin force generation is lacking. We present a theoretical model of muscle contraction based on the conformational movements of individu...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.104.056846
更新日期:2005-06-01 00:00:00
abstract::Sedimentation velocity is a powerful tool for the analysis of complex solutions of macromolecules. However, sample turbidity imposes an upper limit to the size of molecular complexes currently amenable to such analysis. Furthermore, the breadth of the particle size distribution, combined with possible variations in th...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(99)77273-5
更新日期:1999-02-01 00:00:00
abstract::We report a method to profile the torsional spring properties of proteins as a function of the angle of rotation. The torque is applied by superparamagnetic particles and has been calibrated while taking account of the magnetization dynamics of the particles. We record and compare the torsional profiles of single Prot...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2013.01.027
更新日期:2013-03-05 00:00:00
abstract::Cellular sensory systems often respond not to the absolute levels of inputs but to the fold-changes in inputs. Such a property is called fold-change detection (FCD) and is important for accurately sensing dynamic changes in environmental signals in the presence of fluctuations in their absolute levels. Previous studie...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2013.10.039
更新日期:2014-01-07 00:00:00