Depolarization-induced calcium responses in sympathetic neurons: relative contributions from Ca2+ entry, extrusion, ER/mitochondrial Ca2+ uptake and release, and Ca2+ buffering.

Depolarization-induced calcium responses in sympathetic neurons: relative contributions from Ca2+ entry, extrusion, ER/mitochondrial Ca2+ uptake and release, and Ca2+ buffering. Research Abstract Details 

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Depolarization-induced calcium responses in sympathetic neurons: relative contributions from Ca2+ entry, extrusion, ER/mitochondrial Ca2+ uptake and release, and Ca2+ buffering. Abstract Text:

Michael Patterson,James Sneyd,David D Friel,

Many models have been developed to account for stimulus-evoked [Ca(2+)] responses, but few address how responses elicited in specific cell types are defined by the Ca(2+) transport and buffering systems that operate in the same cells. In this study, we extend previous modeling studies by linking the time course of stimulus-evoked [Ca(2+)] responses to the underlying Ca(2+) transport and buffering systems. Depolarization-evoked [Ca(2+)](i) responses were studied in sympathetic neurons under voltage clamp, asking how response kinetics are defined by the Ca(2+) handling systems expressed in these cells. We investigated five cases of increasing complexity, comparing observed and calculated responses deduced from measured Ca(2+) handling properties. In Case 1, [Ca(2+)](i) responses were elicited by small Ca(2+) currents while Ca(2+) transport by internal stores was inhibited, leaving plasma membrane Ca(2+) extrusion intact. In Case 2, responses to the same stimuli were measured while mitochondrial Ca(2+) uptake was active. In Case 3, responses were elicited as in Case 2 but with larger Ca(2+) currents that produce larger and faster [Ca(2+)](i) elevations. Case 4 included the mitochondrial Na/Ca exchanger. Finally, Case 5 included ER Ca(2+) uptake and release pathways. We found that [Ca(2+)](i) responses elicited by weak stimuli (Cases 1 and 2) could be quantitatively reconstructed using a spatially uniform model incorporating the measured properties of Ca(2+) entry, removal, and buffering. Responses to strong depolarization (Case 3) could not be described by this model, but were consistent with a diffusion model incorporating the same Ca(2+) transport and buffering descriptions, as long as endogenous buffers have low mobility, leading to steep radial [Ca(2+)](i) gradients and spatially nonuniform Ca(2+) loading by mitochondria. When extended to include mitochondrial Ca(2+) release (Case 4) and ER Ca(2+) transport (Case 5), the diffusion model could also account for previous measurements of stimulus-evoked changes in total mitochondrial and ER Ca concentration.

Depolarization-induced calcium responses in sympathetic neurons: relative contributions from Ca2+ entry, extrusion, ER/mitochondrial Ca2+ uptake and release, and Ca2+ buffering. Publishing Authors By Initials

M Patterson,J Sneyd,DD Friel,

For similar natural sciences: time: time factors research abstracts see: natural sciences: time: time factors research

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Depolarization-induced calcium responses in sympathetic neurons: relative contributions from Ca2+ entry, extrusion, ER/mitochondrial Ca2+ uptake and release, and Ca2+ buffering. Journal Published:

PUBLICATION TYPE: Research Support, N.I.H., Extr

Journal: The Journal of general physiology

VOLUME: 129

Page Numbers: 29-56

Journal Abbreviation: J. Gen. Physiol.

ISSN: 0022-1295

DAY: 3

MONTH: Jan

YEAR: 2007

Depolarization-induced calcium responses in sympathetic neurons: relative contributions from Ca2+ entry, extrusion, ER/mitochondrial Ca2+ uptake and release, and Ca2+ buffering. Information

Number of References:

LANGUAGE: eng

NlmUniqueID: 2985110

Depolarization-induced calcium responses in sympathetic neurons: relative contributions from Ca2+ entry, extrusion, ER/mitochondrial Ca2+ uptake and release, and Ca2+ buffering. Keywords Mesh Terms:

KEYWORDS: Time Factors

MESH TERMS: metabolism

Chemical & Substance for Abstract: Depolarization-induced calcium responses in sympathetic neurons: relative contributions from Ca2+ entry, extrusion, ER/mitochondrial Ca2+ uptake and release, and Ca2+ buffering. Information

Substance Name: Calcium

Registry Number: 7440-70-2

Grant and Affiliation Information for Depolarization-induced calcium responses in sympathetic neurons: relative contributions from Ca2+ entry, extrusion, ER/mitochondrial Ca2+ uptake and release, and Ca2+ buffering.

AFFILIATION: Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA.

Country: United States

AGENCY: United States NINDS

GRANT: NS 33514

ACRONYM: NS

MEDLINETA: J Gen Physiol

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