McCarron John G, Olson Marnie L
Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, John Arbuthnott Building, 27 Taylor Street, Glasgow G4 0NR, Scotland, United Kingdom.
J Biol Chem. 2008 Mar 14;283(11):7206-18. doi: 10.1074/jbc.M708923200. Epub 2007 Dec 20.
Whether or not the sarcoplasmic reticulum (SR) is a continuous, interconnected network surrounding a single lumen or comprises multiple, separate Ca2+ pools was investigated in voltage-clamped single smooth muscle cells using local photolysis of caged compounds and Ca2+ imaging. The entire SR could be depleted or refilled from one small site via either inositol 1,4,5-trisphosphate receptors (IP3R) or ryanodine receptors (RyR) suggesting the SR is luminally continuous and that Ca2+ may diffuse freely throughout. Notwithstanding, regulation of the opening of RyR and IP3R, by the [Ca2+] within the SR, may create several apparent SR elements with various receptor arrangements. IP3R and RyR may appear to exist entirely on a single store, and there may seem to be additional SR elements that express either only RyR or only IP3R. The various SR receptor arrangements and apparently separate Ca2+ storage elements exist in a single luminally continuous SR entity.
利用笼锁化合物的局部光解和钙离子成像技术，在电压钳制的单个平滑肌细胞中研究了肌浆网（SR）是围绕单个管腔的连续、相互连接的网络，还是由多个独立的钙离子池组成。整个肌浆网可以通过肌醇1,4,5-三磷酸受体（IP3R）或兰尼碱受体（RyR）从一个小位点耗尽或重新填充，这表明肌浆网在管腔内是连续的，钙离子可能在其中自由扩散。尽管如此，肌浆网内的钙离子浓度对RyR和IP3R开放的调节，可能会产生具有各种受体排列的几个明显的肌浆网元件。IP3R和RyR可能似乎完全存在于单个储存库中，并且可能似乎存在仅表达RyR或仅表达IP3R的其他肌浆网元件。各种肌浆网受体排列和明显分开的钙离子储存元件存在于单个管腔内连续的肌浆网实体中。
