Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, J. B. Winsløwsvej 21, 3. DK-5000, Odense C, Denmark.
Hypertension. 2012 Nov;60(5):1346-51. doi: 10.1161/HYPERTENSIONAHA.112.198879. Epub 2012 Sep 17.
In nephrotic syndrome, plasminogen is aberrantly filtered from plasma to the urinary space and activated along the tubular system. In vitro, plasmin increases ENaC current by proteolytic cleavage of the γ-subunit. It was hypothesized that preeclampsia is associated with plasmin-dependent ability of tubular fluid to activate ENaC. Urine was sampled from 16 preeclamptic (PE) patients and 17 normotensive pregnant women (Ctrl). Urine was analyzed for plasmin(ogen), creatinine, albumin, aldosterone, Na(+), K(+), proteolytic activity, and for its effect on inward current in cortical collecting duct cells (M1 cells) by whole-cell patch clamp. In PE, urine plasmin(ogen): creatinine ratio was elevated 40-fold (geometric mean, 160 versus 4 µg/g; P<0.0001) and urine aldosterone: creatinine ratio was suppressed to 25% of Ctrl (geometric mean, 27 versus 109 µg/g; P<0.001). A significant negative correlation was found in PE between urinary plasmin(ogen) and aldosterone (P<0.05). In PE, proteolytic activity was detected at 90 to 75 kD by gelatin zymography in 14 of 16 patients and confirmed by serine protease assay. Immunoblotting showed active plasmin in PE urine. Whole-cell inward current increased in M1 cells on exposure to urine from PE (173±21%; n=6; P<0.001). The increase in current was abolished by amiloride (2 μmol/L; P<0.001), α(2)-antiplasmin (1 μmol/L; P<0.001), and heat denaturation (P<0.001). Preeclampsia is associated with urinary excretion of plasmin(ogen) and plasmin-dependent activation of ENaC by urine. Proteolytic activation of ENaC by plasmin may contribute to Na(+) retention and hypertension in preeclampsia.
在肾病综合征中，纤溶酶原从血浆中异常滤过到尿腔，并沿肾小管系统激活。在体外，纤溶酶通过对 γ-亚基的蛋白水解切割增加 ENaC 电流。假设子痫前期与管状液激活 ENaC 的纤溶酶依赖性能力有关。从 16 例子痫前期（PE）患者和 17 例正常妊娠妇女（Ctrl）中采集尿液。分析尿液中的纤溶酶原（ogen）、肌酐、白蛋白、醛固酮、Na(+)、K(+)、蛋白水解活性，以及通过全细胞膜片钳技术分析其对皮质集合管细胞（M1 细胞）内向电流的影响。在 PE 中，尿纤溶酶原：肌酐比值升高 40 倍（几何均数，160 与 4 µg/g；P<0.0001），尿醛固酮：肌酐比值降低至 Ctrl 的 25%（几何均数，27 与 109 µg/g；P<0.001）。PE 中尿纤溶酶原和醛固酮呈显著负相关（P<0.05）。在 16 例患者中有 14 例在 PE 中通过明胶酶谱检测到 90 至 75 kD 的蛋白水解活性，并通过丝氨酸蛋白酶测定得到证实。免疫印迹显示 PE 尿中有活性纤溶酶。将 M1 细胞暴露于 PE 尿液中，全细胞膜内向电流增加（173±21%；n=6；P<0.001）。电流增加被阿米洛利（2 µmol/L；P<0.001）、α(2)-抗纤溶酶（1 µmol/L；P<0.001）和热变性（P<0.001）所抑制。子痫前期与尿液中纤溶酶原的排泄和尿液中纤溶酶依赖的 ENaC 激活有关。纤溶酶对 ENaC 的蛋白水解激活可能导致子痫前期的 Na(+)潴留和高血压。
