Da Silva Alda Pereira, Marinho Cláudia, Gonçalves Ma Conceição, Monteiro Cristina, Laires Ma José, Falcão Luiz Menezes, Nogueira José Braz, Bich Manuel
Laboratório de Genética, Centro de Metabolismo e Endocrinologia, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal.
Rev Port Cardiol. 2010 Mar;29(3):403-12.
Erythrocytes may play an important role in regulating blood pressure as storage sites for nitric oxide (NO). The objective of this work was to determine whether factors related to variations in erythrocyte metabolism associated with NO bioavailability, such as the activity of two enzymes--methemoglobin reductase (MHbR) and glutathione reductase (GSHR)--may help explain age-related increased blood pressure.
The sample consisted of 468 individuals of both sexes, 237 hypertensive (HT) and 231 normotensive (NT), aged between 18 and 98 years (48.81 +/- 19.46). The activity of MHbR (micromol.g Hb-1.min-1) and of GSHR (micromol.g Hb-1.min-1) was determined in erythrocytes by spectrophotometry. The statistical methods used were the Mann-Whitney test, Spearman's correlation coefficient and binary logistic regression.
In this population, age was a risk factor for hypertension (OR=1.055, 95% CI = 1.045-1.065, p < 0.001). There was a significant difference in erythrocyte activity of these enzymes between normotensive and hypertensive subjects, with lower values in hypertensives: MHbR-NT = 16.97 (3.82-34.63), HT = 16.26 (3.26-37.10), p = 0.012; and GSHR-NT=57.60 (21.59-96.58), HT = 39.26 (23.07-90.27), p < 0.001. Enzyme activity was inversely correlated with age (MHbR: r = -0.193, p < 0.001; GSHR: r = -0.757, p < 0.001). MHbR correlated directly with GSHR only in hypertensive patients (r = 0.343, p = 0.034), which was not observed in normotensives.
Age was a risk factor for hypertension. The erythrocyte activity of glutathione and metahemoglobin reductases, essential for redox balance and nitric oxide bioavailability in erythrocytes, may contribute only partially to the increased prevalence of age-related hypertension, and other factors should be taken into consideration, such as nutrition and antihypertensive medication.
红细胞作为一氧化氮（NO）的储存场所，可能在调节血压中发挥重要作用。本研究的目的是确定与红细胞代谢变化相关的因素，这些因素与NO生物利用度有关，例如两种酶——高铁血红蛋白还原酶（MHbR）和谷胱甘肽还原酶（GSHR）的活性——是否有助于解释与年龄相关的血压升高。
样本包括468名男女个体，年龄在18至98岁之间（48.81±19.46），其中237名高血压患者（HT）和231名血压正常者（NT）。通过分光光度法测定红细胞中MHbR（微摩尔·克血红蛋白⁻¹·分钟⁻¹）和GSHR（微摩尔·克血红蛋白⁻¹·分钟⁻¹）的活性。所采用的统计方法为曼-惠特尼检验、斯皮尔曼相关系数和二元逻辑回归。
在该人群中，年龄是高血压的一个危险因素（OR=1.055，95%可信区间=1.045-1.065，p<0.001）。血压正常者和高血压患者之间这些酶的红细胞活性存在显著差异，高血压患者的值较低：MHbR-NT=16.97（3.82-34.63），HT=16.26（3.26-37.10），p=0.012；GSHR-NT=57.60（21.59-96.58），HT=39.26（23.07-90.27），p<0.001。酶活性与年龄呈负相关（MHbR：r=-0.193，p<0.001；GSHR：r=-0.757，p<0.001）。仅在高血压患者中，MHbR与GSHR呈正相关（r=0.343，p=0.034），血压正常者中未观察到这种情况。
年龄是高血压的一个危险因素。谷胱甘肽和高铁血红蛋白还原酶的红细胞活性对红细胞中的氧化还原平衡和一氧化氮生物利用度至关重要，可能仅部分导致与年龄相关的高血压患病率增加，还应考虑其他因素，如营养和抗高血压药物。
