Institute of Adaptive and Spaceflight Physiology, Graz, Austria.
Eur J Clin Invest. 2011 Nov;41(11):1180-5. doi: 10.1111/j.1365-2362.2011.02523.x. Epub 2011 Mar 24.
Aim of this study was to test the hypothesis that after presyncope, some blood hormone pools increase while others decrease.
In twelve healthy male adults, we determined plasma volume changes with plasma mass densitometry and hormone levels. The following were compared: supine rest, presyncope and 20-min post-presyncopal supine rest. We determined plasma renin activity (PRA), aldosterone, adrenocorticotropic hormone (ACTH), adrenomedullin and vasopressin (AVP) from venous blood samples.
Using passive 4-min 70° head-up tilt followed by 4-min sequences of additional lower body negative pressure of increasing intensity (15 mmHg steps), presyncope occurred after 11·6 ± 2·8 min, at which time plasma volume was reduced by 15·5 ± 7·4%, aldosterone increased by 37%, ACTH by 75%, PRA by 187% and AVP about 16-fold in average (all P < 0·01); no significant changes in adrenomedullin were seen. Twenty-min post-presyncope, ACTH increased above presyncopal levels (+36%, P < 0·05), aldosterone by 35% (P = 0·07). PRA (-47%, P < 0·01) and AVP (-84%, P < 0·05) decreased below presyncopal but were still above supine control (P < 0·01); similarly, plasma density fell by 2·17 ± 0·97 g L(-1) below presyncopal (P < 0·01), but above supine control (P < 0·05), indicating rapid recovery (83% of initial plasma volume).
We conclude that during the 20-min supine post-syncopal period, plasma volume, PRA and AVP return closer to baseline but aldosterone and ACTH continue increasing. The magnitude of observed concentration changes cannot be explained by haemoconcentration/haemodilution, rather it appears that the observed changes are indicative of hormone-specific endocrine activation patterns in the recovery phase.
本研究旨在验证以下假说，即在晕厥前期，一些血液激素水平会增加，而另一些则会降低。
我们对 12 名健康男性成年人进行了研究，通过血浆质量密度测定法和激素水平来检测血浆容量的变化。比较了以下三种状态：仰卧位休息、晕厥前期和晕厥后 20 分钟的仰卧位休息。我们从静脉血样中测定了血浆肾素活性（PRA）、醛固酮、促肾上腺皮质激素（ACTH）、肾上腺髓质素和血管加压素（AVP）的水平。
通过被动 4 分钟 70°头高位倾斜，然后进行 4 分钟序列的额外下体负压强度增加（15mmHg 步长），在 11.6±2.8 分钟时发生晕厥，此时血浆容量减少了 15.5±7.4%，醛固酮增加了 37%，ACTH 增加了 75%，PRA 增加了 187%，AVP 平均增加了约 16 倍（均 P<0.01）；肾上腺髓质素未见明显变化。晕厥后 20 分钟，ACTH 水平高于晕厥前期（增加 36%，P<0.05），醛固酮增加 35%（P=0.07）。PRA（减少 47%，P<0.01）和 AVP（减少 84%，P<0.05）低于晕厥前期，但仍高于仰卧位对照（P<0.01）；同样，血浆密度比晕厥前期下降了 2.17±0.97g·L-1（P<0.01），但仍高于仰卧位对照（P<0.05），表明恢复迅速（初始血浆容量的 83%）。
我们的结论是，在晕厥后 20 分钟的仰卧位恢复期内，血浆容量、PRA 和 AVP 更接近基线水平，但醛固酮和 ACTH 继续增加。观察到的浓度变化的幅度不能用血液浓缩/稀释来解释，而似乎表明在恢复阶段观察到的变化是激素特异性内分泌激活模式的指示。
