Kliche Katrin, Kuhn Michaela, Hillebrand Uta, Ludwig Yvonne, Stock Christian, Oberleithner Hans
Institute of Physiology II, University of Münster, Münster, Germany.
Cell Physiol Biochem. 2006;18(4-5):265-74. doi: 10.1159/000097673.
There is growing evidence that aldosterone acts on heart where it causes cellular remodeling and hypertrophy. Since it is still unclear whether aldosterone directly acts on cardiomyocytes or indirectly, by an altered electrolyte balance in the organism, we applied atomic force microscopy (AFM) in primary cultures of neonatal mouse cardiomyocytes to measure hormone-induced changes in cell volume and plasma membrane surface. AFM measures cell volume and, at the same time, provides quantitative information on cell surface properties. Neonatal mouse cardiomyocytes were cultured for 28 hours in absence or presence of 100 nM aldosterone. Spironolactone was applied as a selective aldosterone receptor antagonist. At the microscopic level, single cell volume and single cell surface were found unchanged by aldosterone. However, nanoscopy of the cell surface, i.e. analysis of the plasma membrane at the nanometer level, revealed a specific increase in plasma membrane nano-enfoldings (roughness). This aldosterone-mediated increase in cell surface roughness was completely prevented by spironolactone. We conclude: (i) Aldosterone directly acts upon cardiomyocytes. (ii) At the microscopic level, no changes of cell volume and cell surface are detectable. (iii) At the nanoscopic level, aldosterone increases plasma membrane roughness. These nanometer changes, detectable only with AFM in cells scanned in fluid after fixation under physiological conditions, indicate plasma membrane remodeling of cardiomyocytes by mineralocorticoids.
越来越多的证据表明，醛固酮作用于心脏，导致细胞重塑和肥大。由于醛固酮是直接作用于心肌细胞还是通过机体电解质平衡改变间接作用尚不清楚，我们在新生小鼠心肌细胞原代培养物中应用原子力显微镜（AFM）来测量激素诱导的细胞体积和质膜表面变化。AFM可测量细胞体积，同时提供有关细胞表面特性的定量信息。将新生小鼠心肌细胞在不存在或存在100 nM醛固酮的情况下培养28小时。使用螺内酯作为选择性醛固酮受体拮抗剂。在显微镜水平上，发现醛固酮对单细胞体积和单细胞表面无影响。然而，细胞表面的纳米显微镜检查，即在纳米水平分析质膜，显示质膜纳米褶皱（粗糙度）有特定增加。螺内酯完全阻止了醛固酮介导的细胞表面粗糙度增加。我们得出以下结论：（i）醛固酮直接作用于心肌细胞。（ii）在显微镜水平上，未检测到细胞体积和细胞表面的变化。（iii）在纳米水平上，醛固酮增加质膜粗糙度。这些仅在生理条件下固定后在液体中扫描的细胞中用AFM才能检测到的纳米级变化，表明盐皮质激素对心肌细胞质膜的重塑作用。
