Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2 Pt 1
pubmed:dateCreated
1997-6-6
pubmed:abstractText
Secretion of catecholamines from neuroendocrine cells is relatively slow and it is likely that redistribution and buffering of Ca2+ is a major factor for delaying the response after a stimulus. In fact, in a recent study (Chow, R. H., J. Klingauf, and E. Neher. 1994. Time course of Ca2+ concentration triggering exocytosis in neuroendocrine cells. Proc. Natl. Acad. Sci. U.S.A. 91:12765-12769) Chow et al. concluded that the concentration of free calcium ([Ca2+]i) at a release site peaks at < 10 microM during short-step depolarizations, and then decays to baseline over tens of milliseconds. To check whether such a time course is consistent with diffusion theory, we modeled buffered diffusion in the vicinity of a Ca2+ channel pore. Peak [Ca2+]i and the slow decay were well simulated when release-ready granules were randomly distributed within a regular grid of Ca2+ channels with mean interchannel distances of 300-600 nm. For such large spacings, however, the initial rise in [Ca2+]i was underestimated, suggesting that a small fraction of the release-ready pool (approximately 10%) experiences much higher [Ca2+]i, and thus might be colocalized with Ca2+ channels. A model that accommodates these findings then correctly predicts many recent observations, including the result that single action potentials evoke near-synchronous transmitter release with low quantal yield, whereas trains of action potentials lead to desynchronized release, but with severalfold increased quantal yield. The simulations emphasize the role of Ca2+ not only in triggering, but also in modulating the secretory response: buffers are locally depleted by residual Ca2+ of a preceding stimulus, so that a second pulse leads to a larger peak [Ca2+]i at the fusion sites.
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-1309652, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-1315621, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-1331424, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-1354503, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-1381122, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-1465619, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-1538782, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-1675264, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-2015091, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-2108959, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-2317553, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-2412607, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-2418887, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-2566336, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-2721487, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-2865362, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-3108033, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-3181158, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-3382715, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-3495885, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-3803567, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-4346703, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-5350329, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-6261850, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-6296372, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-6329349, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-6698635, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-6959149, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7659162, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7696493, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7778189, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7809118, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7809151, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7876083, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7906397, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7907072, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7935764, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7946349, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7948669, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7954835, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-7969483, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8006030, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8171016, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8182469, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8235626, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8271200, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8393324, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8427700, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8431551, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8461136, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8551339, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8699245, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8778287, http://linkedlifedata.com/resource/pubmed/commentcorrection/9017195-8789951
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0006-3495
pubmed:author
pubmed:issnType
Print
pubmed:volume
72
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
674-90
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Modeling buffered Ca2+ diffusion near the membrane: implications for secretion in neuroendocrine cells.
pubmed:affiliation
Department of Membrane Biophysics, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany.
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