JournalAdvances in experimental medicine and biology
PubMed ID8109389
The effect of Ca2+ on the time course of force generation in frog skinned muscle fibres has been investigated using laser flash photolysis of the caged-calcium, either nitr-5 or DM-Nitrophen. Gradations in the rate and extent of contraction could be achieved by changing the energy of the laser pulse, which ... More
Roles of Ca2+ and crossbridge kinetics in determining the maximum rates of Ca2+ activation and relaxation in rat and guinea pig skinned trabeculae.
AuthorsPalmer S, Kentish JC
JournalCirc Res
PubMed ID9686757
'We examined the influences of Ca2+ and crossbridge kinetics on the maximum rate of force development during Ca2+ activation of cardiac myofibrils and on the maximum rate of relaxation. Flash photolysis of diazo-2 or nitrophenyl-EGTA was used to produce a sudden decrease or increase, respectively, in [Ca2+] within Triton-skinned trabeculae ... More
MgADP promotes a catch-like state developed through force-calcium hysteresis in tonic smooth muscle.
AuthorsKhromov A, Somlyo AV, Somlyo AP
JournalBiophys J
PubMed ID9746533
'Tonic rabbit femoral artery and phasic rabbit ileum smooth muscles permeabilized with Triton X-100 were activated either by increasing [Ca2+] from pCa > 8.0 to pCa 6.0 (calcium-ascending protocol) or contracted at pCa 6.0 before lowering [Ca2+] (calcium-descending protocol). The effects of, respectively, high [MgATP]/low [MgADP] [10 mM MgATP + ... More
Role of myosin heavy chain composition in kinetics of force development and relaxation in rat myocardium.
AuthorsFitzsimons DP, Patel JR, Moss RL
JournalJ Physiol
PubMed ID9782168
'1. The effects of ventricular myosin heavy chain (MHC) composition on the kinetics of activation and relaxation were examined in both chemically skinned and intact myocardial preparations from adult rats. Thyroid deficiency was induced to alter ventricular MHC isoform expression from approximately 80% alpha-MHC/20% beta-MHC in euthyroid rats to 100% ... More
Skeletal muscle relaxation with diazo-2: the effect of altered pH.
AuthorsPalmer RE, Simnett SJ, Mulligan IP, Ashley CC
JournalBiochem Biophys Res Commun
PubMed ID1764084
'In a fatigued muscle fibre, the concentrations of ADP, Pi and H+ are all increased and relaxation is slowed. We have used the technique of laser flash photolysis of the caged calcium-chelator, diazo-2, to investigate the direct effect of changes in pH (pH 6.5, 7.0, 7.5) upon tension during relaxation ... More
Controlling cell chemistry with caged compounds.
AuthorsAdams SR, Tsien RY
JournalAnnu Rev Physiol
PubMed ID8466191
Photorelease techniques for raising or lowering intracellular Ca2+.
AuthorsZucker R
JournalMethods Cell Biol
PubMed ID8201983
Ca2+ and activation mechanisms in skeletal muscle.
AuthorsAshley CC, Mulligan IP, Lea TJ
JournalQ Rev Biophys
PubMed ID2047521
Striated scallop muscle relaxation: fast force transients produced by photolysis of Diazo-2.
AuthorsPalmer RE, Mulligan IP, Nunn C, Ashley CC
JournalBiochem Biophys Res Commun
PubMed ID2328006
Relaxation of the myosin regulated striated adductor muscles of Pecten maximus was initiated by the photolysis of the caged Ca2+ chelator, Diazo-2. The fibres relaxed to approximately 30% of the maximum tension with a mean half-time of 17.9 +/- 1.6 ms (n = 7, temp 12 degrees C), much faster ... More
Caged compounds: photorelease technology for control of cellular chemistry and physiology.
AuthorsEllis-Davies GC
JournalNat Methods
PubMed ID17664946
Caged compounds are light-sensitive probes that functionally encapsulate biomolecules in an inactive form. Irradiation liberates the trapped molecule, permitting targeted perturbation of a biological process. Uncaging technology and fluorescence microscopy are 'optically orthogonal': the former allows control, and the latter, observation of cellular function. Used in conjunction with other technologies ... More
The effect of EMD 57033, a novel cardiotonic agent, on the relaxation of skinned cardiac and skeletal muscle produced by photolysis of diazo-2, a caged calcium chelator.
AuthorsSimnett SJ, Lipscomb S, Ashley CC, Mulligan IP
JournalPflugers Arch
PubMed ID8272375
EMD 57033 is thought to produce its potentiating effect by increasing the apparent calcium sensitivity of myofibrils. We have investigated the effect of 10 microM EMD 57033 on relaxation speed, induced by flash photolysis of 2mM diazo-2 (a caged Ca2+ chelator), in skinned semitendinosus frog muscle fibres and guinea-pig trabeculae. ... More
Calcium ions are involved in Escherichia coli chemotaxis.
AuthorsTisa LS, Adler J
JournalProc Natl Acad Sci U S A
PubMed ID1465403
Escherichia coli regulates intracellular free Ca2+ at about 90 nM [Gangola, P. & Rosen, B. P. (1987) J. Biol. Chem. 262, 12570-12574]. To increase intracellular free Ca2+, nitr-5/Ca2+, a "caged" Ca2+ compound, was electroporated into cells and then its affinity for Ca2+ was reduced by exposure to 370-nm light. Upon ... More
Induction of synaptic long-term potentiation after opioid withdrawal.
AuthorsDrdla R, Gassner M, Gingl E, Sandkühler J,
JournalScience
PubMed ID19590003
mu-Opioid receptor (MOR) agonists represent the gold standard for the treatment of severe pain but may paradoxically also enhance pain sensitivity, that is, lead to opioid-induced hyperalgesia (OIH). We show that abrupt withdrawal from MOR agonists induces long-term potentiation (LTP) at the first synapse in pain pathways. Induction of opioid ... More
Visualization of stochastic Ca2+ signals in the formed somites during the early segmentation period in intact, normally developing zebrafish embryos.
AuthorsLeung CF, Miller AL, Korzh V, Chong SW, Sleptsova-Freidrich I, Webb SE,
JournalDev Growth Differ
PubMed ID19712266
Localized Ca(2+) signals were consistently visualized in the formed somites of intact zebrafish embryos during the early segmentation period. Unlike the regular process of somitogenesis, these signals were stochastic in nature with respect to time and location. They did, however, occur predominantly at the medial and lateral boundaries within the ... More
Rapid relaxation of single frog skeletal muscle fibres following laser flash photolysis of the caged calcium chelator, diazo-2.
AuthorsMulligan IP, Ashley CC
JournalFEBS Lett
PubMed ID2507351
Diazo-2 is a calcium chelator based on BAPTA [(1989) J. Biol. Chem., in press], whose electron withdrawing diazoacetyl group may be rapidly (2000 s-1) converted photochemically to an electron donating carboxymethyl group by exposure to near ultraviolet light, producing an increase in its calcium affinity (Kd changes from 2.2 microM ... More
Does the use of DM-nitrophen, nitr-5, or diazo-2 interfere with the measurement of indo-1 fluorescence?
AuthorsHadley RW, Kirby MS, Lederer WJ, Kao JP
JournalBiophys J
PubMed ID8312490
Emission spectra of the photolabile Ca2+ chelators DM-nitrophen, nitr-5, and diazo-2 were studied alone, and in the presence of indo-1, to investigate potential interactions that would make the simultaneous manipulation and ratiometric measurement of the intracellular Ca2+ concentration difficult. Neither diazo-2 nor its photoproduct were found to be significantly fluorescent, ... More
Adaptation of single cardiac ryanodine receptor channels.
AuthorsVélez P, Györke S, Escobar AL, Vergara J, Fill M
JournalBiophys J
PubMed ID9017196
Single cardiac ryanodine receptor (RyR) channel adaptation was previously defined with Ca2+ stimuli produced by flash photolysis of DM-nitrophen (caged-Ca+2). Photolysis of DM-nitrophen induced a very fast Ca+2 overshoot (Ca+2 spike) at the leading edge of the Ca+2 stimuli. It has been suggested that adaptation (tau approximately 1.3 s) may ... More
Residual Ca2+ and short-term synaptic plasticity.
AuthorsKamiya H, Zucker RS
JournalNature
PubMed ID7935792
At many synapses, the amount of transmitter released by action potentials increases progressively during a train of spikes. This enhancement of evoked transmitter release grows during tetanic stimulation with several time constants, each bearing a different name (facilitation: tens to hundreds of milliseconds; augmentation: several seconds; potentiation: several minutes), and ... More
Phosphorylation of myosin regulatory light chain eliminates force-dependent changes in relaxation rates in skeletal muscle.
AuthorsPatel JR, Diffee GM, Huang XP, Moss RL
JournalBiophys J
PubMed ID9449336
The rate of relaxation from steady-state force in rabbit psoas fiber bundles was examined before and after phosphorylation of myosin regulatory light chain (RLC). Relaxation was initiated using diazo-2, a photolabile Ca2+ chelator that has low Ca2+ binding affinity (K(Ca) = 4.5 x 10(5) M(-1)) before photolysis and high affinity ... More
Determinants of relaxation rate in skinned frog skeletal muscle fibers.
AuthorsWahr PA, Johnson JD, Rall JA
JournalAm J Physiol
PubMed ID9611126
The influences of sarcomere uniformity and Ca2+ concentration on the kinetics of relaxation were examined in skinned frog skeletal muscle fibers induced to relax by rapid sequestration of Ca2+ by the photolysis of the Ca2+ chelator, diazo-2, at 10 degreesC. Compared with an intact fiber, diazo-2-induced relaxation exhibited a faster ... More
Photolytic manipulation of [Ca2+]i reveals slow kinetics of potassium channels underlying the afterhyperpolarization in hippocampal pyramidal neurons.
AuthorsSah P, Clements JD
JournalJ Neurosci
PubMed ID10233997
The identity of the potassium channel underlying the slow, apamin-insensitive component of the afterhyperpolarization current (sIAHP) remains unknown. We studied sIAHP in CA1 pyramidal neurons using simultaneous whole-cell recording, calcium fluorescence imaging, and flash photolysis of caged compounds. Intracellular calcium concentration ([Ca2+]i) peaked earlier and decayed more rapidly than sIAHP. ... More
Abnormal contractile function in transgenic mice expressing a familial hypertrophic cardiomyopathy-linked troponin T (I79N) mutation.
AuthorsMiller T, Szczesna D, Housmans PR, Zhao J, de Freitas F, Gomes AV, Culbreath L, McCue J, Wang Y, Xu Y, Kerrick WG, Potter JD
JournalJ Biol Chem
PubMed ID11060294
This study characterizes a transgenic animal model for the troponin T (TnT) mutation (I79N) associated with familial hypertrophic cardiomyopathy. To study the functional consequences of this mutation, we examined a wild type and two I79N-transgenic mouse lines of human cardiac TnT driven by a murine alpha-myosin heavy chain promoter. Extensive ... More
Bombesin-like peptides depolarize rat hippocampal interneurones through interaction with subtype 2 bombesin receptors.
AuthorsLee K, Dixon AK, Gonzalez I, Stevens EB, McNulty S, Oles R, Richardson PJ, Pinnock RD, Singh L
JournalJ Physiol
PubMed ID10420015
1. Whole-cell patch-clamp recordings were made from visually identified hippocampal interneurones in slices of rat brain tissue in vitro. Bath application of the bombesin-like neuropeptides gastrin-releasing peptide (GRP) or neuromedin B (NMB) produced a large membrane depolarization that was blocked by pre-incubation with the subtype 2 bombesin (BB2) receptor antagonist ... More
Novel action of BAPTA series chelators on intrinsic K+ currents in rat hippocampal neurones.
AuthorsLancaster B, Batchelor AM
JournalJ Physiol
PubMed ID10639100
1. Whole-cell recordings were made from rat CA1 neurones in brain slices. When electrodes contained diazo-2 (2 mM) or dibromo BAPTA (1 mM) a large steady-state outward current (hundreds of picoamps) developed within 5 min of breakthrough at a VH of -60 mV. BAPTA itself (1 mM) caused qualitatively similar ... More
Regions of the 110-kDa regulatory subunit M110 required for regulation of myosin-light-chain-phosphatase activity in smooth muscle.
AuthorsGailly P, Wu X, Haystead TA, Somlyo AP, Cohen PT, Cohen P, Somlyo AV
JournalEur J Biochem
PubMed ID8706736
To characterize the in situ interactions between the subunits (regulatory 110 kDa, M110; 21-kDa, M21 and catalytic, 37-kDa, PP1c) of smooth muscle myosin phosphatase (SMPP-1M), we determined, in Triton-X-100-permeabilized rabbit portal vein contracted with microcystin-LR, the ability of the following fragments of M110 to regulate relaxation induced by exogenous PP1c: ... More
Calcium transients and the effect of a photolytically released calcium chelator during electrically induced contractions in rabbit rectococcygeus smooth muscle.
AuthorsArner A, Malmqvist U, Rigler R
JournalBiophys J
PubMed ID9746530
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 ... More
Photolysis of caged compounds characterized by ratiometric confocal microscopy: a new approach to homogeneously control and measure the calcium concentration in cardiac myocytes.
AuthorsLipp P, Lüscher C, Niggli E
JournalCell Calcium
PubMed ID8732265
Here we describe the subcellularly uniform control of the intracellular Ca2+ concentration ([Ca2+]i) by flash photolysis of caged Ca2+ or a caged Ca2+ buffer. A mixture of the two Ca2+ indicators Fluo-3 and Fura-red was used together with a laser-scanning confocal microscope to reveal spatial aspects of intracellular Ca2+ signals. ... More
The role of MgADP in force maintenance by dephosphorylated cross-bridges in smooth muscle: a flash photolysis study.
AuthorsKhromov A, Somlyo AV, Trentham DR, Zimmermann B, Somlyo AP
JournalBiophys J
PubMed ID8599668
The effect of [MgADP] on relaxation from isometric tension, initiated by reducing free [Ca2+] through photolysis of the caged photolabile Ca2+ chelator diazo-2, was determined at 20 degrees C in alpha-toxin permeabilized tonic (rabbit femoral artery, Rf) and phasic (rabbit bladder, Rb) smooth muscle. In Rf, the shape of the ... More