Kifor I, Moore T J, Fallo F, Sperling E, Menachery A, Chiou C Y, Williams G H
Endocrine-Hypertension Division, Brigham and Women's Hospital, Boston, Massachusetts 02115.
Endocrinology. 1991 Mar;128(3):1277-84. doi: 10.1210/endo-128-3-1277.
To determine whether dietary sodium intake modifies the generation of adrenal-produced angiotensins and/or their relative proportions, Sprague-Dawley rats were maintained on a low (0.02%), normal (0.4%), or high (1.5%) sodium intake for 5 days. The animals were then killed by decapitation at 0900 h, and their adrenal glands were removed and dissected into two parts: capsular tissue, containing the zona glomerulosa (ZG), and the decapsulated adrenal gland. The tissue was frozen in liquid nitrogen and extracted, and the individual angiotensins [angiotensin-II (AII), angiotensin-III (AIII), angiotensin-I (AI), and Des-Asp-angiotensin-I (Des-Asp-AI)] were separated by HPLC and quantitated by RIA. On a normal sodium intake, the molar contents of the four angiotensins were similar in ZG, ranging from 3.1-6.6 pmol/g, although AII was present in a 60-70% higher concentration than AIII. In the decapsulated adrenal, the concentrations of the various angiotensins were again similar, but the absolute levels (per g tissue) were significantly (P less than 0.02) less than those in the ZG layer. With sodium restriction, the AII content increased more than 2-fold in the ZG, but not in the decapsulated adrenal tissue. In contrast, both AI and Des-Asp-AI significantly (P less than 0.01) decreased with sodium restriction, so that their contents on the low salt diet were only 15-20% of those observed on the high sodium diet. Thus, there was an inverse correlation (P less than 0.001) between the salt content of rat chow and the AII content of the ZG. The correlation between salt intake and AI as well as Des-Asp-AI levels was direct and significant (P less than 0.02). The AIII level in the ZG was similar on all diets. After a lag period, ZG AII increased sharply between 16-48 h of sodium restriction. These data document that sodium intake has a profound effect on the angiotensin content of the ZG, with sodium restriction substantially increasing the levels of AII while reducing the level of its substrate, AI. This also appears to be unique for glomerulosa cells, as in the decapsulated adrenal gland there is little if any change with sodium restriction. We conclude that these sodium-mediated changes in tissue AII production may be involved in the increased responsiveness of glomerulosa cells to aldosterone secretagogues during sodium restriction.
为了确定膳食钠摄入量是否会改变肾上腺产生的血管紧张素的生成及其相对比例，将Sprague-Dawley大鼠分别维持在低（0.02%）、正常（0.4%）或高（1.5%）钠摄入量的饮食条件下5天。然后在上午9点将动物断头处死，取出肾上腺并切成两部分：包含球状带（ZG）的被膜组织和去被膜的肾上腺。组织在液氮中冷冻后提取，通过高效液相色谱法分离各个血管紧张素[血管紧张素-II（AII）、血管紧张素-III（AIII）、血管紧张素-I（AI）和脱天冬氨酸血管紧张素-I（Des-Asp-AI）]，并通过放射免疫分析法进行定量。在正常钠摄入量下，四种血管紧张素在ZG中的摩尔含量相似，范围为3.1 - 6.6 pmol/g，尽管AII的浓度比AIII高60 - 70%。在去被膜的肾上腺中，各种血管紧张素的浓度再次相似，但绝对水平（每克组织）显著低于（P < 0.02）ZG层中的水平。钠限制时，ZG中AII含量增加超过2倍，但去被膜的肾上腺组织中没有增加。相反，AI和Des-Asp-AI在钠限制时显著降低（P < 0.01），因此它们在低盐饮食中的含量仅为高钠饮食中观察到的含量的15 - 20%。因此，大鼠饲料中的盐含量与ZG中AII含量之间存在负相关（P < 0.001）。盐摄入量与AI以及Des-Asp-AI水平之间的相关性是直接且显著的（P < 0.02）。所有饮食条件下ZG中AIII水平相似。经过一段滞后时间后，钠限制16 - 48小时之间ZG中的AII急剧增加。这些数据表明，钠摄入量对ZG中的血管紧张素含量有深远影响，钠限制会大幅增加AII水平，同时降低其底物AI的水平。这似乎也是球状带细胞所特有的，因为在去被膜的肾上腺中，钠限制几乎没有变化。我们得出结论，这些钠介导的组织AII生成变化可能参与了钠限制期间球状带细胞对醛固酮分泌刺激物反应性的增加。
