Calcium mobilization via intracellular ion channels, store organization and mitochondria in smooth muscle

McCarron, John G. and Chalmers, Susan and Wilson, Calum and Sandison, Mairi E.; (2016) Calcium mobilization via intracellular ion channels, store organization and mitochondria in smooth muscle. In: Vascular Ion Channels in Physiology and Disease. Springer, Berlin, pp. 233-254. ISBN 978-3-319-29635-7

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    Abstract

    In smooth muscle, Ca2+ release from the internal store into the cytoplasm occurs via inositol trisphosphate (IP3R) and ryanodine receptors (RyR). The internal Ca2+ stores containing IP3R and RyR may be arranged as multiple separate compartments with various IP3R and RyR arrangements, or there may be a single structure containing both receptors. The existence of multiple stores is proposed to explain several physiological responses which include the progression of Ca2+ waves, graded Ca2+ release from the store and various local responses and sensitivities. We suggest that, rather than multiple stores, a single luminally-continuous store exists in which Ca2+ is in free diffusional equilibrium throughout. Regulation of Ca2+ release via IP3R and RyR by the local Ca2+ concentration within the stores explains the apparent existence of multiple stores and physiological processes such as graded Ca2+ release and Ca2+ waves. Close positioning of IP3R on the store with mitochondria or with receptors on the plasma membrane creates ‘IP3 junctions’ to generate local responses on the luminally-continuous store.