Slezák J, Schulze W, Okruhlicová L, Tribulová N, Singal P K
Institute for Heart Research, Slovak Academy of Sciences, Bratislava, Slovak Republic.
Mol Cell Biochem. 1997 Nov;176(1-2):107-12.
In order to understand the functional significance of Na,K-ATPase subunits as well as their isoenzymes, a precise subcellular localization of these in the myocyte is a crucial prerequisite. Cytochemical, immunofluorescence, preembedding immunogold and horse radish peroxidase-diaminobenzidine methods, demonstrated alpha 1 isoenzyme immunoreactivity on the sarcolemma, T-tubules and the subsarcolemmal cisterns of the adult cardiac myocytes. Cytochemically, ouabain resistant Na,K-ATPase precipitate was localized only in the subsarcolemmal cisterns and junctional sarcoplasmic reticulum. For alpha 2 isoenzyme, immuno-reactivity was demonstrated on the sarcolemma as well as in all areas of the myocytes in particularly a close proximation to the sarcoplasmic reticulum and microsomes. For alpha 3 isoenzyme, only a weak insignificant signal was noted on the sarcolemma, intercalated disc and sarcoplasm. It is suggested that cytochemical ouabain resistant precipitate present in subsarcolemmal cisterns and junctional sarcoplasmic reticulum represent alpha 1 isoenzyme of Na,K-ATPase. A differential as well as unique localization of alpha subunit isoenzymes of Na,K-ATPase in specific structures of cardiac myocytes may suggest importance in physiological function at these sites.
为了理解钠钾-ATP酶亚基及其同工酶的功能意义，在心肌细胞中对其进行精确的亚细胞定位是一个关键前提。细胞化学、免疫荧光、包埋前免疫金和辣根过氧化物酶-二氨基联苯胺方法显示，成年心肌细胞的肌膜、T小管和肌膜下池存在α1同工酶免疫反应性。细胞化学分析表明，哇巴因抗性钠钾-ATP酶沉淀仅位于肌膜下池和连接肌浆网。对于α2同工酶，在肌膜以及心肌细胞的所有区域均显示出免疫反应性，尤其与肌浆网和微粒体紧密相邻。对于α3同工酶，仅在肌膜、闰盘和肌浆中观察到微弱的无显著意义的信号。提示存在于肌膜下池和连接肌浆网中的细胞化学哇巴因抗性沉淀代表钠钾-ATP酶的α1同工酶。钠钾-ATP酶α亚基同工酶在心肌细胞特定结构中的差异以及独特定位可能表明其在这些部位的生理功能中具有重要意义。
