Buffer kinetics shape the spatiotemporal pattern of IP3-evoked Ca2+ signals

Dargan, Sheila L. and Parker, Ian 2003. Buffer kinetics shape the spatiotemporal pattern of IP3-evoked Ca2+ signals. The Journal of Physiology 553 (3) , pp. 775-788. 10.1113/jphysiol.2003.054247

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Abstract

Ca2+ liberation through inositol 1,4,5-trisphosphate receptors (IP3Rs) plays a universal role in cell regulation, and specificity of cell signalling is achieved through the spatiotemporal patterning of Ca2+ signals. IP3Rs display Ca2+-induced Ca2+ release (CICR), but are grouped in clusters so that regenerative Ca2+ signals may remain localized to individual clusters, or propagate globally between clusters by successive cycles of Ca2+ diffusion and CICR. We used confocal microscopy and photoreleased IP3 in Xenopus oocytes to study how these properties are modulated by mobile cytosolic Ca2+ buffers. EGTA (a buffer with slow ‘on-rate’) speeded Ca2+ signals and ‘balkanized’ Ca2+ waves by dissociating them into local signals. In contrast, BAPTA (a fast buffer with similar affinity) slowed Ca2+ responses and promoted ‘globalization’ of spatially uniform Ca2+ signals. These actions are likely to arise through differential effects on Ca2+ feedback within and between IP3R clusters, because Ca2+ signals evoked by influx through voltage-gated channels were little affected. We propose that cell-specific expression of Ca2+-binding proteins with distinct kinetics may shape the time course and spatial distribution of IP3-evoked Ca2+ signals for specific physiological roles.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Biosciences
Subjects:	Q Science > QP Physiology
Publisher:	Wiley-Blackwell
Last Modified:	23 Jul 2020 01:51
URI:	https://orca.cardiff.ac.uk/id/eprint/75178

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