Sodium pump inhibitors in blood pressure regulation and in profibrotic signaling in salt sensitive hypertension and aging

在第一项临床研究中，39名健康受试者（53 +/- 11岁; 20名男性和19名女性）每日总NaCl摄入量为50 mmol（低盐）和150 mmol（高盐），各持续4周，随机顺序。在基线（非标准化盐摄入量）和高盐和低盐摄入后，测量血浆和尿液中的动态血压（ABP）和海蟾毒配基（MBG）。基线时血浆MBG（P-MBG）与24小时收缩压（r= 0.43，P=0.007）和舒张压（r=0.32，P=0.047）相关。有趣的是，性别特异性分析显示，这些关系仅在男性中显着。与低盐相比，高盐饮食增加了P-MBG（P=0.029），主要是由男性的结果驱动的。男性P-MBG应答者与无应答者（高于与低于高盐诱导的P-MBG升高的中位数）相比，收缩压（10.4 +/- 6.4 vs. 0.0 +/- 6.0 mmHg; P=0.003）和舒张压（6.7 +/- 5.0 vs. -0.6 +/- 3.6 mmHg; P=0.001）盐敏感性显著增强。我们的结论是，在男性MBG增加24小时ABP，和Dahl-S相似，4周的高盐诱导MBG反应伴随着盐敏感性显着增加。然而，这些模式似乎是性别特异性的，在人类女性中没有观察到。 在第二个实验中，我们研究了三组雄性Dahl-S（每组n=6）：低盐（0.1%NaCl）饮食（LS）大鼠;高盐（8%NaCl）饮食7周（HS）大鼠;高盐饮食7周，随后3E 9抗MBG mAb治疗1周（HSAB）大鼠。观察收缩压（SBP）、超声心动图（ECHO）参数、肌酐清除率、血糖（MBG）水平、肾脏重量、左心室（LV）和肾脏重量。 在HS与LS中，SBP增加74 mm Hg（P<0.01），血浆MBG加倍肾MBG排泄增加6倍（P<0.05）（P<0.01），组织重量增加（LV：2.37 +/- 0.05 vs. 1.62 +/- 0.04 g/kg BW，P<0.01;主动脉：4.44 +/- 0.17 vs. 3.01 +/- 0.06 mg/mm/kg BW，P<0.01;肾脏：11.29 +/- 0.2 vs. 8.37 +/- 0.11 g/kg BW，P<0.01），LV缩短分数降低（46 +/- 1.2% vs. 58 +/-2%，P<0.01），肌酐清除率降低（1.94 +/- 0.25 vs. 2.61 +/- 0.18 mg/mL，P<0.01）。 单次腹腔注射抗MBG单克隆抗体治疗高血压性DS（HSAB组）收缩压降低35 mm Hg仅1周后，左室重量显著降低（P<0.01）（2.03 +/- 0.08 g/kg BW，P<0.01），（3.72 +/- 0.06 mg/mm/kg BW，P<0.05），肾脏（10.7 +/- 0.29 g/kg BW，P<0.05），增加LV缩短分数（52 +/-1%，P<0.05），并将肌酐清除率恢复至对照（LS）水平（2.82 +/- 0.22 mg/mL，P<0.05）。 在高血压DS中，存在与TGF-β信号传导有关的基因表达上调的组织特异性模式（LV：TGF-β 1、TGF-β 2、MAPK 3、CTGF、SMADs、胶原蛋白-1;主动脉：TGF-β 1、TGF-β 2、TGF-β 3、PDGF、纤连蛋白、SNAIL 1、胶原蛋白;肾脏TGF-β 1、ITGB 1、胶原蛋白-1），在MBG免疫中和后下调。 因此，Dahl-S中升高的MBG水平的免疫中和使肾功能正常化，并产生抗高血压和抗重塑作用，其与盐敏感性高血压中由MBG引发的TGF-β诱导的纤维化中涉及的基因的下调相关。

In the first clinical study, 39 healthy subjects (53 +/- 11 years old; 20 males and 19 females) had a total daily NaCl intake of 50 mmol (low-salt) and 150 mmol (high-salt) for 4 weeks each, in random order. Ambulatory blood pressure (ABP) and marinobufagenin (MBG) in plasma and urine were measured at baseline (unstandardized salt intake) and after high- and low-salt intake. At baseline, plasma MBG (P-MBG) was related to 24-hour systolic (r= 0.43, P=0.007) and diastolic (r=0.32, P=0.047) BP. Interestingly, gender-specific analyses revealed that these relationships were significant in males only. Compared to low-salt, high-salt diet increased P-MBG (P=0.029), mainly driven by results in men. Male P-MBG responders vs. non-responders (above vs. below median of high-salt induced P-MBG increase) had markedly enhanced systolic (10.4 +/- 6.4 vs. 0.0 +/- 6.0 mmHg; P=0.003) and diastolic (6.7 +/- 5.0 vs. -0.6 +/- 3.6 mm Hg; P=0.001) BP salt sensitivity. We conclude that in males MBG increases with 24-hour ABP, and similar to Dahl-S, 4-weeks of high-salt induced MBG response is accompanied by marked increase in salt sensitivity. However, these patterns seem to be gender specific and are not observed in human females. In the second experiment we studied three groups of male Dahl-S (n=6 each): rats on a low salt (0.1% NaCl) diet (LS); rats on a high salt (8% NaCl) diet for 7 weeks (HS); and rats on a high salt diet for 7 weeks, followed by 3E9 anti-MBG mAb treatment for 1 week (HSAB). SBP, ECHO parameters, creatinine clearance, levels of MBG, weights of aortae, left ventricles (LV) and kidneys were assessed. In HS vs. LS, SBP increased by 74 mm Hg (P<0.01), plasma MBG doubled (P<0.05), renal MBG excretion increased 6-fold (P<0.01), tissue weights increased (LV: 2.37 +/- 0.05 vs. 1.62 +/- 0.04 g/kg BW, P<0.01; aorta: 4.44 +/- 0.17 vs. 3.01 +/- 0.06 mg/mm per kg BW, P<0.01; kidneys: 11.29 +/- 0.2 vs. 8.37 +/- 0.11 g/kg BW, P<0.01), LV fractional shortening decreased (46 +/- 1.2% vs. 58 +/- 2%, P<0.01), and creatinine clearance decreased (1.94 +/- 0.25 vs. 2.61 +/- 0.18 mg/mL, P<0.01). A single intra-peritoneal administration of anti-MBG monoclonal antibody to hypertensive DS (HSAB group) reduced SBP by 35 mm Hg (P<0.01) after just 1 week, markedly reduced weights of LV (2.03 +/- 0.08 g/kg BW, P<0.01), aortae (3.72 +/- 0.06 mg/mm per kg BW, P<0.05), and kidneys (10.7 +/- 0.29 g/kg BW, P<0.05), increased LV fractional shortening (52 +/- 1%, P<0.05) vs. HS group, and restored the creatinine clearance to control (LS) levels (2.82 +/- 0.22 mg/mL, P<0.05). In hypertensive DS there was a tissue-specific pattern of up-regulation of expression of genes, implicated in TGF-beta-signaling (LV: TGF-beta1, TGF-beta2, MAPK3, CTGF, SMADs, collagen-1; aorta: TGF-beta1, TGF-beta2, TGF-beta3, PDGF, fibronectin, SNAIL1, collagens; kidneys TGF-beta1, ITGB1, collagen-1), that was down-regulated following immunoneutralization of MBG. Thus, immunoneutralization of heightened MBG levels in Dahl-S normalized renal function and produced an anti-hypertensive and an anti-remodeling effect associated with down-regulation of genes implicated in TGF-beta-induced fibrosis initiated by MBG in salt-sensitive hypertension.