Pulsed laser imaging of rapid Ca2+ gradients in excitable cells

Monck, Jonathan R.; Robinson, Iain; Escobar, Ariel L.; Vergara, Julio L.; Fernández, Julio M.

doi:10.1016/s0006-3495(94)80554-5

Cited by 83 publications

(72 citation statements)

References 40 publications

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“…Although chromaffin cells do not form synapses onto other cells, secretion from individual cells may be polarized in the direction of blood vessels (24,26), for example, by restricting the zones of Ca2+ entry. Indeed, in chromaffin cells Ca2+ channels appear to be clustered (30). Such clustering apparently results in "hot spots" of secretion, as has been reported by Schroeder et al (24), using carbon-fiber electrodes having tip diameters of about 2 ,um.…”

mentioning

confidence: 52%

Time course of Ca2+ concentration triggering exocytosis in neuroendocrine cells.

Chow

Klingauf

Neher

1994

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

178

142

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We have used the secretory response of chromaffin cells to estimate the submembrane intracellular Ca2+ concentration ([Ca2+]1) "seen" by secretory granules during short depolarizations. The rate of secretion during a depolarization was assessed by combining the electrochemical method of amperometry and electrical capacitance measurements. The *To whom reprint requests should be addressed. 12765The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

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mentioning

confidence: 52%

Time course of Ca2+ concentration triggering exocytosis in neuroendocrine cells.

Chow

Klingauf

Neher

1994

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

178

142

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“…1A) that continues even after the presynaptic neuron has been repolarized (15,17) while the intracellular Ca2+ concentration is thought to remain high. As measured in chromaffin cells (19) J r(t')Im(t -t')dt'. [1] Minis were usually elicited by partial activation of the presynaptic Ca2+ current through depolarizations to approximately -35 mV, so that quanta were discretely resolvable (Fig.…”

Section: Methodsmentioning

confidence: 99%

The kinetics of quantal transmitter release from retinal amacrine cells.

Borges

Gleason²,

Turelli³

et al. 1995

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

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Exocytosis of transmitter at most synapses is a very fast process triggered by the entry of Ca2+ during an action potential. A reasonable expectation is that the fast step of exocytosis is followed by slow steps readying another vesicle for exocytosis but the identity and kinetics of these steps are presently unclear. A critical distinction between different models of transmitter release lies in the rate at which vesicles of transmitter are exocytosed (1). Release rates from nonneuronal secretory cells (2-5) and neurons (6-9) have been measured by monitoring the increase in cell capacitance consequent upon fusion of vesicle membrane with the plasmalemma. A limitation imposed by the tiny capacitance of a transmitter vesicle is that, for ordinary neurons, single exocytic events are well below the limit of resolution. Conventional electrophysiological recording can detect single exocytic events as "miniature" currents or voltages (10, 11), but in general, synaptic current is not directly related to release rate since at any point it depends on the history of release up to that point. A way of estimating release rate while still exploiting the good resolution of synaptic current recording comes from considering synaptic current as the convolution (12) of mini waveform with the release rate (13,14). Finding the release rate is then a matter of finding the deconvolution of these two measurable functions, the mini current time course and the evoked synaptic current time course.

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“…It has been suggested that the possible cause of such heterogeneity is through the Ca 2+ hotspots that are generated in the membrane (Monck et al, 1994) or even through Ca 2+ release from intracellular reservoirs, such as mitochondria (Pozzan and Rizzuto, 2000;Montero et al, 2002) or the endoplasmic reticulum (ER) . One simple explanation for this heterogeneity is the organization of the cytosolic space itself, which is structured as a dense intricate network of dynamic cytoskeletal polygonal cages that can be readily studied in live cells by transmitted-light microscopy (Giner et al, 2005;Giner et al, 2007).…”

Section: Cytoskeletal Organization and The Distribution Of Fluorescenmentioning

confidence: 99%

The F-actin cortical network is a major factor influencing the organization of the secretory machinery in chromaffin cells

Torregrosa‐Hetland¹,

Villanueva²,

Giner³

et al. 2011

Journal of Cell Science

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SummaryWe have studied how the F-actin cytoskeleton is involved in establishing the heterogeneous intracellular Ca 2+ levels ([Ca 2+ ] i ) and in the organization of the exocytotic machinery in cultured bovine chromaffin cells. Simultaneous confocal visualization of [Ca 2+ ] i and transmitted light studies of the cytoskeleton showed that, following cell stimulation, the maximal signal from the Ca 2+ -sensitive fluorescent dye Fluo-3 was in the empty cytosolic spaces left by cytoskeletal cages. This was mostly due to the accumulation of the dye in spaces devoid of cytoskeletal components, as shown by the use of alternative Ca 2+ -insensitive fluorescent cytosolic markers. In addition to affecting the distribution of such compounds in the cytosol, the cytoskeleton influenced the location of L-and P-Q-type Ca 2+ channel clusters, which were associated with the borders of cytoskeletal cages in resting and stimulated cells. Indeed, syntaxin-1 and synaptotagmin-1, which are components of the secretory machinery, were present in the same location. Furthermore, granule exocytosis took place at these sites, indicating that the organization of the F-actin cytoskeletal cortex shapes the preferential sites for secretion by associating the secretory machinery with preferential sites for Ca 2+ entry. The influence of this cortical organization on the propagation of [Ca 2+ ] i can be modelled, illustrating how it serves to define rapid exocytosis.

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Pulsed laser imaging of rapid Ca2+ gradients in excitable cells

Cited by 83 publications

References 40 publications

Time course of Ca2+ concentration triggering exocytosis in neuroendocrine cells.

Time course of Ca2+ concentration triggering exocytosis in neuroendocrine cells.

The kinetics of quantal transmitter release from retinal amacrine cells.

The F-actin cortical network is a major factor influencing the organization of the secretory machinery in chromaffin cells

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