目的:高血压是美国心血管疾病发病率和死亡率的主要原因之一,对黑人妇女的影响不成比例。内皮源性一氧化氮(eNO)可显著调节人体血压,在黑人人群中,NO介导的血管舒张功能受损。以前使用NO合酶抑制剂的研究,由于压力反射缓冲,NG-单甲基-L-精氨酸(L-NMMA)不能完全确定NO对血压的贡献。因此,在本研究中,我们使用了三美沙芬,神经节阻滞剂,抑制压力反射缓冲并研究黑人女性在L-NMMA输注期间对血压的NO调节。
方法:以每分钟250μg/kg的剂量将L-NMMA与4mg/min剂量的三美沙芬组合输注以消除压力反射机制。通过连续心电图监测获得心率(HR),用容量钳制法测量连续血压。两次输注期间收缩压(SBP)的升高用于估计NO对血压的贡献。
结果:十个黑人(年龄范围30-50岁,体重指数[BMI]30-45kg/m2),和九名白人女性(年龄范围30-50岁,体重指数30-45kg/m2)纳入本研究。在自主神经封锁期间,黑人和白人女性之间SBP的下降没有差异(-20±16.45vs.-24±15.49mmHg,分别为;P=0.659)。当自主神经阻滞与L-NMMA联合使用时,与白人女性相比,黑人女性的SBP显着增加(54±13.62vs.39±09.64mmHg,分别;分别P=0.022)。
结论:黑人和白人女性的自主神经血压调节相似。然而,与白人女性相比,黑人女性对血压的贡献明显更大。
背景:ClinicalTrials.gov:NCT01122407。
OBJECTIVE: Hypertension is one of the major causes of cardiovascular morbidity and mortality in the USA and disproportionately affects Black women. Endothelial-derived nitric oxide (eNO) substantially regulates blood pressure in humans, and impaired NO-mediated vasodilation has been reported in the Black population. Previous studies using an NO synthase inhibitor, NG-monomethyl-L-arginine (L-NMMA) did not fully determine the NO contribution to blood pressure because of
baroreflex buffering. Therefore, in the present study we used trimethaphan, a ganglionic blocker, to inhibit
baroreflex buffering and study NO modulation of blood pressure in Black women during L-NMMA infusion.
METHODS: L-NMMA at doses of 250 μg/kg per minute was infused in combination with trimethaphan at doses of 4 mg/min to eliminate
baroreflex mechanisms. Heart rate (HR) was obtained with continuous electrocardiogram monitoring, and continuous blood pressure was measured with the volume clamp method. The increase in systolic blood pressure (SBP) during both infusions was used to estimate the contribution of NO to blood pressure.
RESULTS: Ten Black (age range 30-50 years, body mass index [BMI] 30-45 kg/m2), and nine White women (age range 30-50 years, body mass index 30-45 kg/m2) were enrolled in this study. During autonomic blockade, there was no difference in the decrease in SBP between Black and White women (- 20 ± 16.45 vs. - 24 ± 15.49 mm Hg, respectively; P = 0.659). When autonomic blockade was combined with L-NMMA, Black women had a significant increase in SBP compared to White women (54 ± 13.62 vs. 39 ± 09.64 mm Hg, respectively; P = 0.022, respectively).
CONCLUSIONS: Autonomic blood pressure regulation was similar between Black and White women. However, NO contribution to blood pressure was significantly greater in Black women compared to White women.
BACKGROUND: ClinicalTrials.gov: NCT01122407.