Presynaptic strontium dynamics and synaptic transmission.
AuthorsXu-Friedman MA, Regehr WG
JournalBiophys J
PubMed ID10096899
'Strontium can replace calcium in triggering neurotransmitter release, although peak release is reduced and the duration of release is prolonged. Strontium has therefore become useful in probing release, but its mechanism of action is not well understood. Here we study the action of strontium at the granule cell to Purkinje ... More
Kinetic properties of DM-nitrophen and calcium indicators: rapid transient response to flash photolysis.
AuthorsEscobar AL, Velez P, Kim AM, Cifuentes F, Fill M, Vergara JL
JournalPflugers Arch
PubMed ID9242727
'We describe a high temporal resolution confocal spot microfluorimetry setup which makes possible the detection of fluorescence transients elicited by Ca2+ indicators in response to large (50-200 microM), short duration (< 100 ns), free [Ca2+] transients generated by laser flash photolysis of DM-nitrophen (DM-n; caged Ca2+). The equilibrium and kinetic ... More
Patch-clamp recording of charge movement, Ca(2+) current, and Ca(2+) transients in adult skeletal muscle fibers
AuthorsWang ZM, Messi ML, Delbono O
JournalBiophys J
PubMed ID10545370
'Intramembrane charge movement (Q), Ca(2+) conductance (G(m)) through the dihydropyridine-sensitive L-type Ca(2+) channel (DHPR) and intracellular Ca(2+) fluorescence (F) have been recorded simultaneously in flexor digitorum brevis muscle fibers of adult mice, using the whole-cell configuration of the patch-clamp technique. The voltage distribution of Q was fitted to a Boltzmann ... More
Extracellular Ca2+ depletion contributes to fast activity-dependent modulation of synaptic transmission in the brain.
AuthorsRusakov DA, Fine A
JournalNeuron
PubMed ID12546823
'Synaptic activation is associated with rapid changes in intracellular Ca(2+), while the extracellular Ca(2+) level is generally assumed to be constant. Here, using a novel optical method to measure changes in extracellular Ca(2+) at high spatial and temporal resolution, we find that brief trains of synaptic transmission in hippocampal area ... More
Detection of Ca(2+)-transients elicited by flash photolysis of DM-nitrophen with a fast calcium indicator.
AuthorsEscobar AL, Cifuentes F, Vergara JL
JournalFEBS Lett
PubMed ID7758592
A confocal spot detection optical setup was used to record fluorescence signals in response to calcium pulses, elicited by flash photolysis of DM-nitrophen, with the calcium indicators CaOrange-5N and Fluo-3. Our results yield the following conclusions: [Ca2+] changes are almost perfect spikes at pCa 9 and broader transients followed by ... More
T-jump study of calcium binding kinetics of calcium chelators.
AuthorsNaraghi M
JournalCell Calcium
PubMed ID9481476
Recent experimental studies have investigated the kinetic competition between calcium chelators and the secretion apparatus at a fast central synapse. Simultaneously, mathematical modelling studies indicate the importance of a quantitative knowledge of the binding kinetics of the chelators in studying fast physiological processes operating on a millisecond time scale. Using ... More
Laser photolysis of caged calcium: rates of calcium release by nitrophenyl-EGTA and DM-nitrophen.
AuthorsEllis-Davies GC, Kaplan JH, Barsotti RJ
JournalBiophys J
PubMed ID8789118
Nitrophenyl-EGTA and DM-nitrophen are Ca2+ cages that release Ca2+ when cleaved upon illumination with near-ultraviolet light. Laser photolysis of nitrophenyl-EGTA produced transient intermediates that decayed biexponentially with rates of 500,000 s-1 and 100,000 s-1 in the presence of saturating Ca2+ and 290,000 s-1 and 68,000 s-1 in the absence of ... More
Calcium dynamics associated with a single action potential in a CNS presynaptic terminal.
AuthorsHelmchen F, Borst JG, Sakmann B
JournalBiophys J
PubMed ID9138591
Calcium dynamics associated with a single action potential were studied quantitatively in the calyx of Held, a large presynaptic terminal in the rat brainstem. Terminals were loaded with different concentrations of high- or low-affinity Ca2+ indicators via patch pipettes. Spatially averaged Ca2+ signals were measured fluorometrically and analyzed on the ... More
Properties of tri- and tetracarboxylate Ca2+ indicators in frog skeletal muscle fibers.
AuthorsZhao M, Hollingworth S, Baylor SM
JournalBiophys J
PubMed ID8789107
Recently a number of lower-affinity fluorescent Ca2+ indicators have become available with principal absorbance bands at visible wavelengths. This article evaluates these indicators, as well as two shorter wavelength indicators, mag-fura-5 and mag-indo-1, for their suitability as rapid Ca2+ indicators in frog skeletal muscle fibers. With three lower-affinity tricarboxylate indicators ... More