Chiou C Y, Williams G H, Kifor I
Endocrine-Hypertension Division, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
J Clin Invest. 1995 Sep;96(3):1375-81. doi: 10.1172/JCI118172.
To address the question as to how zona glomerulosa (ZG) cell angiotensin II (Ang II) secretion is regulated, we developed an immuno-cell blot assay to measure its secretion from single cells. We compared these results with those obtained from population studies using a superfusion system. Modulation of Ang II secretion was investigated acutely (by administrating potassium [K+] or captopril) and chronically (by feeding the animals low or high sodium diets). The area of secretory cells, halo areas, and halo intensities varied widely but were highly significantly correlated (P < 0.001) with each other. A disproportionate amount of Ang II was secreted by a small number of large cells. When K+ concentration was increased from 3.6 to 0 mM, superfused ZG cells increased their Ang II secretion 2.32 +/- 0.59-fold. Administration of captopril reduced the K(+)-stimulated Ang II secretion 1.24 +/- 0.07 fold. These findings were reflected in the cell blot assay as a change in the frequency distribution of halo area by K+ and captopril in the same direction as in the population study. In both conditions, the percentage of secretory cells did not change significantly from control. Superfused ZG cells from rats on a low sodium diet secreted 1.85 +/- 0.58-fold more Ang II than cells from sodium-loaded rats (p < 0.05, n = 6). The cell blot assay confirmed these findings with sodium restriction significantly increasing (P < 0.001) both the halo area and its frequency distribution to a larger portion of high secreting cells. However, in contrast to acute treatment with K+ or captopril, the number of secretory cells also doubled. Thus, the individual ZG cell uses two mechanisms to modify Ang II production. In response to acute stimulation and suppression, the amount of Ang II secreted per cell is modified without changing the number of secretary cells. With chronic stimulation, both the amount of Ang II secreted per cell and the number of secretary cells increase.
为了探讨肾小球带（ZG）细胞血管紧张素II（Ang II）分泌是如何调节的，我们开发了一种免疫细胞印迹测定法来测量单个细胞的分泌情况。我们将这些结果与使用灌流系统进行的群体研究结果进行了比较。通过急性（给予钾离子[K+]或卡托普利）和慢性（给动物喂食低钠或高钠饮食）方式研究了对Ang II分泌的调节。分泌细胞的面积、晕环面积和晕环强度差异很大，但彼此之间高度显著相关（P < 0.001）。少量大细胞分泌了不成比例的大量Ang II。当K+浓度从3.6 mM增加到0 mM时，灌流的ZG细胞将其Ang II分泌增加了2.32±0.59倍。给予卡托普利使K+刺激的Ang II分泌减少了1.24±0.07倍。这些发现在细胞印迹测定中表现为晕环面积的频率分布因K+和卡托普利而发生与群体研究相同方向的变化。在两种情况下，分泌细胞的百分比与对照相比均无显著变化。低钠饮食大鼠的灌流ZG细胞分泌的Ang II比高钠负荷大鼠的细胞多1.85±0.58倍（p < 0.05，n = 6）。细胞印迹测定证实了这些发现，即钠限制显著增加（P < 0.001）晕环面积及其频率分布，使其在分泌较高的细胞中占更大比例。然而，与用K+或卡托普利进行急性处理不同，分泌细胞的数量也增加了一倍。因此，单个ZG细胞使用两种机制来改变Ang II的产生。在急性刺激和抑制反应中，每个细胞分泌的Ang II量发生改变，而分泌细胞的数量不变。在慢性刺激下，每个细胞分泌的Ang II量和分泌细胞的数量均增加。
