Somlyo A V, Broderick R, Shuman H, Buhle E L, Somlyo A P
Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia 19104-6083.
Proc Natl Acad Sci U S A. 1988 Aug;85(16):6222-6. doi: 10.1073/pnas.85.16.6222.
The composition and pH of atrial-specific granules of rat heart were determined by electron probe x-ray microanalysis and fluorescence microscopy, respectively. The high (75 mmol/kg of dry weight) calcium content and higher than cytoplasmic concentration of chloride in atrial-specific granules were visualized in high-resolution x-ray maps. The Cl- content of granules and cytoplasm decreased and a bromide gradient (granule greater than cytoplasm) was established during incubation in low-chloride, NaBr-containing solutions. Scanning confocal fluorescence light microscopy of live atria incubated with acridine orange demonstrated dye accumulation, indicative of low intragranular pH. We conclude that the granules represent a hitherto unrecognized intracellular store of cardiac calcium and can develop and maintain an anion gradient, presumably through cotransport by means of a proton-pumping ATPase.
分别通过电子探针X射线微分析和荧光显微镜测定大鼠心脏心房特异性颗粒的组成和pH值。在高分辨率X射线图谱中可以看到心房特异性颗粒中高钙含量（干重75 mmol/kg）以及高于细胞质的氯离子浓度。在含低氯、溴化钠的溶液中孵育期间，颗粒和细胞质中的Cl-含量降低，并建立了溴离子梯度（颗粒大于细胞质）。用吖啶橙孵育活心房的扫描共聚焦荧光显微镜显示有染料积累，表明颗粒内pH值较低。我们得出结论，这些颗粒代表了一种迄今未被认识的心脏钙细胞内储存库，并且可能通过质子泵ATP酶协同转运来形成和维持阴离子梯度。
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