Rapid change of quantal size in PC-12 cells detected by neural networks

Kebir, Selma Tchoketch; Aristizabal, Felipe; Maysinger, Dušica; Glavinović, M.I.

doi:10.1016/j.jneumeth.2004.08.014

Cited by 4 publications

(4 citation statements)

References 53 publications

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“…If the pore initially opens gradually, or if its diameter changes during the decay time, such dynamic changes of the pore size would alter the time course of release significantly, given a very strong dependence of the release on the fusion pore diameter. However, in neuro-endocrine cells even large changes of the quantal size appear not to be associated with the changes of the fusion pore diameter (Kebir et al, 2005). When the diffusion constant in the vesicle was reduced the randomized and non-randomized time courses were different.…”

Section: Vesicular Transmitter and Its Time Course Of Releasementioning

confidence: 92%

“…Amperometric recordings of the unitary quantal events have revealed that the time course of release from neuro-endocrine cells is often much longer, and that the quantal size, amplitude and the time course are much more variable than at either central or peripheral synapses (Wightman et al 1991;Walker et al 1996;Aspinwall et al 1997;Amatore et al 2000;Kebir et al 2005). Biochemical evidence suggests that the catecholamines are stored at high concentrations, but in an osmotically inactive form, on a matrix of chromogranin A, and their release occurs through a process of dimerization of chromogranin A (Uvnas and Aborg 1989;Kelly 1993;Yoo and Lewis 1993).…”

Section: Introductionmentioning

confidence: 99%

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Monte Carlo Simulation of Release of Vesicular Content in Neuroendocrine Cells

2006

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The release of transmitter from the vesicle, its diffusion through the fusion pore, and the cleft and its interaction with the carbon electrode were simulated using the Monte Carlo method. According to the simulation the transmitter release is largely determined by geometric factors--the ratio of the fusion pore cross-sectional and vesicular areas, if the diffusion constant is as in the aqueous solution--but the speed of transmitter dissociation from the gel matrix plays an important role during the rise phase of release. Transmitter is not depleted near the entrance to the fusion pore and there is no cleft-to-vesicle feedback, but the depletion becomes evident if the diffusion constant is reduced, especially if the pore is wide. In general, the time course of amperometric currents closely resembles the time course of the simulated transmitter concentration in the cleft and the time course of release. Surprisingly, even a tenfold change of the electrode efficiency has only a marginal effect on the amplitude or the time course of amperometric currents. Greater electrode efficiency however lowers the cleft concentration, but only if the cleft is narrow. As the cleft widens the current amplitudes diminish and rise times lengthen, but the decay times are less affected. Moreover, the amplitude dependence of the rise and decay times becomes steeper as the cleft widens and/or as the release kinetics slows. Finally, lower diffusion constant of transmitter in the narrow cleft does not further prolong the amperometric currents, whose slow time course reflects slow release kinetics.

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Section: Vesicular Transmitter and Its Time Course Of Releasementioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Monte Carlo Simulation of Release of Vesicular Content in Neuroendocrine Cells

2006

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“…Normal distribution of the cube root of the quantal size distributions would also argue that the vesicle-tovesicle fusion is not prominent in catecholamine-releasing cells at the basal release levels. However, it has been also reported that the distributions of the cube root of the quantal size deviate from the normal distribution, and are skewed to the right and often display two peaks (Glavinoviċ et al, 1998;Westerink et al, 2000;Kebir et al, 2005;Tang et al, 2005). Moreover, the treatments, which rapidly alter the mean quantal size (tetanic stimulation, high [K + ] 0 , mechanical disturbance, .…”

Section: Vesicular and Dense Core Size And Their Dependence On Vesiclmentioning

confidence: 99%

“…. ), change also the shape of their distributions (Glavinoviċ and Trifaro, 2002;Kebir et al, 2005), raising the possibility that they act by enhancing the vesicular fusion.…”

Section: Vesicular and Dense Core Size And Their Dependence On Vesiclmentioning

confidence: 99%

Vesicular roundness and compound release in PC-12 cells

Germain

Maysinger

2006

Journal of Neuroscience Methods

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Glutamate, water and ion transport through a charged nanosize pore

Luca

Glavinović

2007

Biochimica et Biophysica Acta (BBA) - Biomembranes

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The transport of transmitter, ions and water through a positively-charged nanopore was investigated through computer simulations. The physics of the problem is described by a coupled set of Poisson-Nernst-Planck and Navier-Stokes equations in a computational domain consisting a cylindrical pore, whose radius ranged from 1 to 8 nm and which was flanked by two compartments representing the vesicular interior and extra-cellular space. The concentration of co-ions is suppressed and of counter-ions enhanced, especially near the pore wall owing to electrostatic interactions. Glutamate (i.e. the transmitter considered) is negatively charged and is simulated as a counter-ion. The electro-kinetically induced pressure due to the movement of ions is negative and very pronounced near the pore wall where the concentration and flux of counter-ions is very high. The water velocity peaks in the pore center, diminishes to zero at the pore wall, but is constant along the pore axis. The mean velocity of the water/fluid is proportional to the vesicular pressure and pore cross-sectional area. Interestingly it is inversely related to the vesicular glutamate concentration. The factors determining the glutamate flux are complex. The diffusive flux generally predominates for narrow pore, and convective flux may dominate for wide pore if the vesicular pressure is high. Surprisingly at low vesicular pressure the mean total glutamate flux per unit cross-sectional pore area is higher for narrow pores. Higher flux is probably due to the rise of glutamate concentration in the nanopore, which is much more pronounced for narrow nanopores, due to the maintenance of approximate neutrality of charges in the pore and on the pore wall. In conclusion intra-vesicular pressure helps 'flushing-out' the transmitter, but the induced pressure 'drags-out' the water into the extra-cellular space.

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Rapid change of quantal size in PC-12 cells detected by neural networks

Cited by 4 publications

References 53 publications

Monte Carlo Simulation of Release of Vesicular Content in Neuroendocrine Cells

Monte Carlo Simulation of Release of Vesicular Content in Neuroendocrine Cells

Vesicular roundness and compound release in PC-12 cells

Glutamate, water and ion transport through a charged nanosize pore

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