高盐饮食对转染人多巴胺D_5受体突变基因F173L小鼠血压的影响

The effect of high-salt diet on blood pressure in human dopamine D_5 receptor mutated gene transgenic mice

目的研究高盐饮食对转染人多巴胺D5受体突变基因F173L(hD5F173L)小鼠血压的影响及氧化应激和血管紧张素Ⅱ1型受体(AT1R)表达的改变。方法转染hD5F173L小鼠和转染人正常基因(hD5 WT)小鼠均随机分为正常盐饮食(0.4%NaCl)、高盐饮食(3%NaCl)、高盐并给予坎地沙坦[3%NaCl+坎地沙坦1mg/(kg·d)]3组,每组6～8只,2周后通过颈动脉插管测量小鼠血压。光泽精法测量其肾脏膜蛋白烟酰胺腺嘌呤二核苷酸磷酸(NADPH)氧化酶活性,免疫印迹检测肾脏膜蛋白NADPH氧化酶和AT1R的表达。结果正常饮食情况下,hD5F173L转基因小鼠的血压、肾脏膜蛋白NADPH氧化酶的活性和表达、肾脏AT1R的表达均明显高于hD5 WT转基因小鼠。hD5F173L小鼠高盐组的平均动脉压、肾脏细胞膜蛋白NADPH氧化酶的活性和表达高于正常盐组[平均动脉压(99.3±2.1)比(92.2±5.4)mm Hg,P<0.05]。hD5 WT转基因小鼠高盐组与正常盐组的平均动脉压差异无统计学意义。hD5F173L小鼠高盐并给予坎地沙坦组平均动脉压、肾脏细胞膜蛋白NADPH氧化酶的活性均低于高盐组[平均动脉压(71.1±7.6)比(99.3±2.1)mm Hg,P<0.05]和正常盐组[平均动脉压(71.1±7.6)比(92.2±5.4)mm Hg,P<0.05]。结论多巴胺通过D5受体调节AT1R的功能并调节肾脏氧化应激,对盐敏感性高血压具有一定的调控作用。

Objective To investigate the effects of high-salt diet on blood pressure and on the changes of oxidative stress and angiotensin ]I type 1 receptor （AT1R） in human dopamine D5 receptor mutated gene （hD5F173L） trans- genic mice. Methods hD5F173L and human wild type Ds gene（hD5WT） transgenic mice were randomly divided into three groups： normal-salt diet （0.4% NaC1）, high-salt diet （3% NaCl）, and high-salt diet plus candesartan [3% NaCI＋ candesartan 1 mg/（kg · d）], with 6--8 mice in each group. Blood pressures were monitored by carotid ar- tery cannulation every two weeks. NADPH oxidase activity of membrane protein in the kidney was determined by lucigenin chemiluminescence. Protein expressions of NADPH oxidase and AT^R were detected by Western blot. Results The blood pressure, NADPH oxidase activity and AT~ R expression in the kidneys of hD5F173L transgenic mice were significantly higher than those in wild-type mice on normal salt diet. In hD5F173L transgenic mice, the mean arterial pressure [（99.3±2.1） vs （92.2±5.4） mm Hg, P〈0.05], the activity and expressions of renal NADPH oxidase were increased after exposure to a high-salt diet in comparison to normal diet. While those indices showed no statistic significance in hD5WT transgenic mice. Additionally, the mean arterial pressure was signifi- cantly lower by candesartan and high-salt co-intervention [（71.1 ± 7.6）mm Hg] than by diets of high-salt [（99.3 ±2. 1）mm Hg-] or normal salt [-（92.2±5.41mm Hg] in hD5F173L mice, and so was NADPH oxidase activity. Conclusion Dopamine mediates AT1R activity and oxidative stress in kidney via D5 receptor, which plays an impor- tant role in the regulation of salt-sensitive hypertension.