Increased red cell content of Zn2+ in essential hypertension

The adverse association of animal zinc intake with cardio-cerebrovascular and metabolic risk factors

Background

The effect of zinc intake on cardio-cerebrovascular and metabolic diseases has always been controversial.

Aims

We hoped to evaluate the associations of the daily dietary estimate (DDE) of zinc intake with cardio-cerebrovascular and metabolic risk factors.

Methods

Baseline data from the Study of Women's Health Across the Nation (SWAN) were obtained. Multivariable linear regression analysis was used to examine associations of the DDE of zinc intake with cardio-cerebrovascular and metabolic risk factors.

Results

The smooth curve demonstrated positive associations of the DDE of animal zinc intake with low-density lipoprotein-cholesterol (LDL-C), triglycerides, total cholesterol, fasting blood glucose, insulin, systolic blood pressure (BP) and diastolic BP and an inverse association of the DDE of animal zinc intake with high-density lipoprotein-cholesterol (HDL-C). Consistently, multivariable linear regression models also showed that an increased DDE of animal zinc intake was closely related to a higher risk of cardio-cerebrovascular and metabolic risk factors [systolic BP: 0.37 (0.13, 0.61); diastolic BP: 0.17 (0.02, 0.33); fasting blood glucose: 1.13 (0.67, 1.59); insulin: 0.26 (0.05, 0.47); LDL-C: 0.82 (0.34, 1.29), triglycerides: 1.65 (0.75, 2.55), total cholesterol: 0.91 (0.38, 1.43) and HDL-C: -0.24 (-0.45, -0.03)] when age, race/ethnicity, total family income, smoking status, alcohol consumption and menopausal status were controlled for. Importantly, stratified analysis supported that the independent associations between the DDE of animal zinc intake and risk factors for cardio-cerebrovascular and metabolic diseases were hardly affected by age and body mass index (BMI).

Conclusion

We found that an increased DDE of animal zinc intake was associated with higher cardiovascular and metabolic risks among middle-aged women, which did not support the benefit of zinc intake in reducing cardiovascular and metabolic risks. The association seems to be incongruous with the anti-inflammation and antioxidation physiological functions of zinc. Thus, additional well-designed and prospective studies are needed to confirm this association.

Effect of hypotensive therapy combined with modified diet or zinc supplementation on biochemical parameters and mineral status in hypertensive patients

BACKGROUND

Hypotensive therapy leads to a number of trace elements metabolism disturbances. Zinc balance is frequently affected by antihypertensive treatment.

AIM

To evaluate the effect of a hypotensive treatment, modified diet and zinc supplementation on mineral status and selected biochemical parameters in newly diagnosed hypertensive patients on monotherapy.

METHODS

In the first stage, arterial hypertension in ninety-eight human subjects was diagnosed. In the second stage, antihypertensive monopharmacotherapy was implemented. In the third stage, patients were randomized into three groups and continued antihypertensive monotherapy: group D received an optimal-mineral-content diet, group S received zinc supplementation, and group C had no changes in diet or zinc supplementation. Iron, zinc, and copper concentrations in serum, erythrocytes, urine, and hair were determined. Lipids, glucose, ceruloplasmin, ferritin, albumin, C-reactive protein (CRP), tumor necrosis factor α (TNF-α), nitric oxide (NO), superoxide dismutase (SOD) and catalase (CAT) were assayed in serum.

RESULTS

Antihypertensive monotherapy decreased zinc concentration in serum and erythrocytes and increased the level of zinc in urine, decreased CAT and SOD activity, TNF-α concentration in serum, and increased the level of NO in the serum. Zinc supply led to an increase in zinc concentration in serum, erythrocytes, and hair (in group S only). In the groups with higher zinc intake, decreased glucose concentration in the serum was observed. Significant correlation was seen between the zinc and glucose serum concentrations.

CONCLUSION

Hypotensive drugs disturb zinc status in newly diagnosed hypertensive patients. Antihypertensive monotherapy combined with increased zinc supply in the diet or supplementation favorably modify zinc homeostasis and regulate glucose status without blood pressure affecting in patients with hypertension.

Zinc and redox signaling: perturbations associated with cardiovascular disease and diabetes mellitus

Cellular signal transduction pathways are influenced by the zinc and redox status of the cell. Numerous chronic diseases, including cardiovascular disease (CVD) and diabetes mellitus (DM), have been associated with impaired zinc utilization and increased oxidative stress. In humans, mutations in the MT-1A and ZnT8 genes, both of which are involved in the maintenance of zinc homeostasis, have been linked with DM development. Changes in levels of intracellular free zinc may exacerbate oxidative stress in CVD and DM by impacting glutathione homeostasis, nitric oxide signaling, and nuclear factor-kappa B-dependent cellular processes. Zinc ions have been shown to influence insulin and leptin signaling via the phosphoinositide 3′-kinase/Akt pathway, potentially linking an imbalance of zinc at the cellular level to insulin resistance and dyslipidemia. The oxidative modification of cysteine residues in zinc coordination sites in proteins has been implicated in cellular signaling and regulatory pathways. Despite the many interactions between zinc and cellular stress responses, studies investigating the potential therapeutic benefit of zinc supplementation in the prevention and treatment of oxidative stress-related chronic disease in humans are few and inconsistent. Further well-designed randomized controlled trials are needed to determine the effects of zinc supplementation in populations at various stages of CVD and DM progression.

Selected zinc metabolism parameters in women with arterial hypotension

In the present study, differences between selected zinc parameters in healthy women and arterial hypotension patients were compared. The patients had baseline systolic blood pressure that did not surpass 100 mm Hg. During the orthostatic test, a decrease of over 20 mm Hg was seen and the patients reported dizziness, limpness, and palpitations. The patients had higher levels of lymphocyte zinc than those of the controls and exhibited a positive correlation between serum zinc and the ouabain-dependent zinc efflux from lymphocytes (r = 0.49), and, in turn, this efflux was negatively correlated to the serum aldosterone level (r = -0.35). Except for the differences in their systolic blood pressure and lymphocyte zinc, none of the tested zinc metabolism parameters showed significant differences between the patients and the controls. As in arterial hypertension, the obtained results indicate that zinc plays a significant role in regulation of arterial blood pressure.

Correlations between serum zinc concentrations and oxygen balance parameters in patients with primary arterial hypertension

It has been postulated that increased blood pressure is related to hypersensitivity of arterial chemoreceptors and increased tissue oxygen supply. Arterial blood pressure has been found to be negatively correlated to serum zinc and positively correlated to age, body mass index, and hemoglobin concentrations. The aim of the present investigation was to further explore the relationship between blood pressure and zinc concentrations in serum and blood morphology parameters, iron concentrations, and venous blood gasometry parameters. The study was carried out in two groups. Group Aconsisted of 23 subjects of both sexes suffering from moderate to severe arterial blood pressure. Their mean age was 53.13+/-10.45 yr (range: 23-74 yr). Group B included 48 subjects of mean age 36.7+/-10.0 yr (range: 26-60 yr). This group included 5 patients with arterial hypotension, 37 with hypertension, and the remaining 6 with normal blood pressure. Significant positive correlations between serum zinc and red blood cell count (r = 0.51) and negative with age (r = -0.52) were found. By multiple regression, negative correlations were also found between serum zinc and the diastolic blood pressure and with hemoglobin (r = -0.5). Age was positively correlated to systolic (r = 0.49) and diastolic (r = 0.45) blood pressure parameters and to hemoglobin concentrations (r = 0.33 and r = 0.38, respectively). Buffered and excess bases in blood were negatively correlated to zinc (r = -0.29 in both cases) and to systolic and diastolic blood pressure (r = -0.31 and r = -0.40, respectively). In turn, the systolic and diastolic blood pressure also correlated negatively to the partial pressure of carbon dioxide and positively to venous blood oxygen saturation and to the partial pressure of oxygen. The role of zinc and acid-balance realtionships in blood pressure regulation and in arterial hypertension ethiopatogenesis is disscused.

Role of zinc in regulation of arterial blood pressure and in the etiopathogenesis of arterial hypertension

Increased gastrointestinal absorption and urinary excretion of zinc has been confirmed in experimental and clinical studies on primary arterial hypertension as a result from changes of intracellular and extracellular zinc content. In arterial hypertension, the levels of zinc in serum, lymphocyte, and bone decrease while increasing in heart, erythrocytes, kidney, liver, suprarenal glands and spleen. These changes result in the loss of zinc homeostasis that leads to various degrees of deficiency, not entirely compensated by nutritional factors or increased absorption in the gastrointestinal tract. Loss of zinc homeostasis can be both cause and effect of high blood pressure. In the present review, the role of zinc metabolism changes and its mechanisms in arterial hypertension are discussed.

Are copper, zinc and selenium in erythrocytes valuable biological indexes of nutrition and pathology?

The real significance of the level of trace elements copper, zinc and selenium in erythrocytes is still a matter of debate. This review is an evaluation of the potential value of copper, zinc and selenium in red blood cells in physiology, nutrition and pathology, taking into account the other commonly used indices and the analytical difficulty encountered for erythrocyte determinations. The main analytical methods and reference values in erythrocytes are also presented. The literature of the last 3 decades was analyzed. On the basis of these papers, the role of erythrocyte copper in various pathologies should be re-investigated, especially when they include inflammatory processes or hormonal changes. The main interest of zinc determination in red blood cells concerns thyroid pathology. In general, the value of selenium in erythrocytes agrees with selenium in serum and its determination is often unnecessary.

Zinc, copper, and zinc- or copper-dependent enzymes in human hypertension

Imbalance of zinc and copper status has been hypothesized in human hypertension. A case-control study was carried out to elucidate the possible relationship between zinc and copper status and essential hypertension. Thirty-one subjects affected by mild stable hypertension, pharmacologically untreated, were investigated together with 31 normotensive controls individually matched for sex, age, and smoking habits. Zinc and copper in serum and urine wee measured, and serum activities of alkaline phosphatase (AP), lactic dehydrogenase (LDH), copper-zinc superoxide dismutase (Cu-Zn SOD), lysyl oxidase (LOX), and monoamine oxidase (MAO) were evaluated. No significant difference in serum and urine zinc and copper content as far as in serum activity of zinc (AP and LDH) or copper (Cu-Zn SOD, LOX, and MAO)-dependent enzymes was found between hypertensives and normotensives. Positive relationships were found in normotensives between serum and urine levels of zinc (r = 0.577; p = 0.001) and copper (r = 0.394; p = 0.028), and between serum copper and Cu-Zn SOD (r = 0.534; p = 0.002). In normotensives, diastolic blood pressure and serum zinc were positively related (r = 0.370; p = 0.041). In hypertensives, inverse correlations were observed between diastolic blood pressure and AP (r = -0.498; p = 0.004) and Cu-Zn SOD (r = 0.452; p = 0.011), and between systolic blood pressure and LOX (r = -0.385; p = 0.033). Diastolic blood pressure was related to LDH inversely in hypertensives (r = -0.357; p = 0.049) and positively in normotensives (r = 0.457; p = 0.010). In normotensives, diastolic blood pressure was inversely related with MAO (r = -0.360; p = 0.046). These findings support the hypothesis that an imbalance of zinc and copper status might be involved in human hypertension.

Blood and tissue zinc levels in spontaneously hypertensive rats

Zinc (Zn) determinations were performed on blood plasma and red cells, liver, heart, adrenals, and spleen of spontaneously hypertensive (SHR) and control normotensive (WKY) male rats, 20 weeks of age. SHR revealed higher red cell (p = 2 x 10(-5)) and heart (p = 0.007) Zn levels than WKY rats. The water content of organs was the same in the two strains. When compared with published data, these results suggest an association between high cell Zn levels and hypertension, the meaning of which is briefly discussed.

[Blood cadmium and plasma zinc in hypertensive patients. Apropos of 76 cases]

Changes in total blood cadmium level (CdT), in blood plasma Zinc level (ZnP) and in CdT/ZnP ratio were studied in 39 hypertensive patients compared to 37 healthy subjects. The hypertensive patients were caracterized by a higher CdT level (p less than 10(-5)), a lower ZnP level (p less than 10(-7)) and a higher CdT/ZnP ratio (p less than 10(-7)). A negative correlation was found between CdT and ZnP, and between blood pressure values (systolic and diastolic) and ZnP. A positive correlation was found between blood pressure values and CdT, and therefore CdT/ZnP ratio.

Blood and urinary magnesium, zinc, calcium, free fatty acids, and catecholamines in type A and type B subjects

Twenty type A male students were compared to nineteen type B male students (all in apparently good health), before and after exposure to combined stress (noise and task). Before stress, red blood cell (RBC) Zn concentration is higher (P less than .05) and Zn excretion lower (P less than .05) in type A than in type B people. After stress, type A subjects exhibit changes that are larger and more significant than those of type B individuals. After stress, the type A group shows an important increase of urinary catecholamines (P = 2.10(-5), serum free fatty acids, and urinary Zn (P = .001); a slight increase in plasma magnesium (P less than .05); and a small but significant decrease in RBC Mg (P less than .02). These results suggest that type A subjects are more sensitive to stress than are type B people and more readily lose their intracellular Mg, the rise in plasma Mg being a transient one, probably consecutive to the cellular loss. The present observations are in good agreement with published data: ie, the psychological characteristics of type A personalities; their greater susceptibility to ischemic heart disease, which has been associated with Mg deficiency; the possible role of hypomagnesemia in the pathogenesis of hypertension and coronary vasospasm; and the high RBC Zn levels found in hypertensive patients.

Serum concentration of Na, K, Ca, Mg, P, Zn and Cu in patients with essential arterial hypertension

Serum concentration of Na, K, Ca, Mg and inorganic phosphate as well as serum levels of Zn and Cu were determined in control subjects and in patients with essential arterial hypertension (EAH) divided according to the stage of the disease. No significant differences were found between the serum mean levels of Na, K, Ca, Mg, Zn and Cu in controls and in patients with EAH. A significant decrease of the serum Zn was noted in the third stage of EAH. A number of cases with hypomagnesemia and/or hypopotassemia probably caused by a long term uncontrolled therapy was also detected. The concentration of inorganic phosphate was significantly lower in patients with EAH associated with overweight than in hypertensive patients with normal body weight and in controls. It is considered that a sustained study of the complex interrelationship between electrolyte interaction and the functional aspects of the arterial wall could still contribute to a better understanding of pathogenic aspects of EAH and of its complications including those subsequent to modern diuretic therapy.