McCarron, John and Olson, Marnie and Chalmers, Susan (2012) Mitochondrial regulation of cytosolic Ca2+ signals in smooth muscle. Pflügers Archiv European Journal of Physiology, 464 (specia). pp. 51-62.Full text not available in this repository. (Request a copy from the Strathclyde author)
The cytosolic Ca2+ concentration ([Ca2+]c) controls virtually every activity of smooth muscle, including contraction, migration, transcription, division and apoptosis. These processes may be activated by large (>10 μM) amplitude [Ca2+]c increases, which occur in small restricted regions of the cell or by smaller (<1 μM) amplitude changes throughout the bulk cytoplasm. Mitochondria contribute to the regulation of these signals by taking up Ca2+. However, mitochondria’s reported low affinity for Ca2+ is thought to require the organelle to be positioned close to ion channels and within a microdomain of high [Ca2+]. In cultured smooth muscle, mitochondria are highly dynamic structures but in native smooth muscle mitochondria are immobile, apparently strategically positioned organelles that regulate the upstroke and amplitude of IP3-evoked Ca2+ signals and IP3 receptor (IP3R) cluster activity. These observations suggest mitochondria are positioned within the high [Ca2+] microdomain arising from an IP3R cluster to exert significant local control of channel activity. On the other hand, neither the upstroke nor amplitude of voltage-dependent Ca2+ entry is modulated by mitochondria; rather, it is the declining phase of the transient that is regulated by the organelle. Control of the declining phase of the transient requires a high mitochondrial affinity for Ca2+ to enable uptake to occur over the normal physiological Ca2+ range (<1 μM). Thus, in smooth muscle, mitochondria regulate Ca2+ signals exerting effects over a large range of [Ca2+] (∼200 nM to at least tens of micromolar) to provide a wide dynamic range in the control of Ca2+ signals.
|Keywords:||mitochondrial regulation, cytosolic Ca2+ , smooth muscle , Therapeutics. Pharmacology, Physiology, Clinical Biochemistry, Physiology (medical)|
|Subjects:||Medicine > Therapeutics. Pharmacology|
|Department:||Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical Sciences|
|Depositing user:||Pure Administrator|
|Date Deposited:||14 Jun 2012 14:10|
|Last modified:||07 Jan 2017 01:12|