Relationships between urinary electrolytes excretion and central hemodynamics, and arterial stiffness in hypertensive patients

The Influence of Dietary Interventions on Arterial Stiffness in Overweight and Obese Subjects

Arterial stiffness is often increased in overweight/obese subjects before the development of hypertension. It is also one of the earliest indicators of increased cardiovascular disease risk and can be considered a good predictor of the development of subclinical cardiovascular dysfunction. Arterial stiffness is a significant prognostic factor influencing cardiovascular risk, which dietary habits can modify. Obese patients should use the caloric-restricted diet because it augments aortic distensibility, diminishes pulse wave velocity (PWV), and increases the activity of endothelial nitric oxide synthases. High intake of saturated fatty acids (SFA), trans fats, and cholesterol, typical for the Western diet, impairs endothelial function and raises brachial-ankle PMV. The replacement of SFA with monounsaturated (MUFA) or polyunsaturated fatty acids (PUFA) derived from seafood and plants diminishes the risk of arterial stiffness. The dairy product intake (excluding butter) decreases PWV in the general population. The high-sucrose diet causes toxic hyperglycemia and increases arterial stiffness. Complex carbohydrates with a low glycemic index (including isomaltose) should be recommended to keep vascular health. The high sodium intake (>10 g/day), particularly associated with low potassium consumption, has a deleterious effect on arterial stiffness (↑ baPWV). Since vegetables and fruits are good sources of vitamins and phytochemicals, they should be recommended in patients with high PMV. Thus, the dietary recommendation to prevent arterial stiffness should be similar to the Mediterranean diet, which is rich in dairy products, plant oils, and fish, with a minimal red meat intake and five servings of fruits and vegetables daily.

Association between Perceived Salt Intake and Arterial Stiffness

To explore the association of perceived salt intake (SI) level with arterial stiffness in the community population in northern China. We enrolled participants who completed the health questionnaire, physical examination, and brachial-ankle pulse wave velocity (baPWV) test during 2010-2019 and divided them into <6 g (low SI), 6-10 g (medium SI), and >10 g (high SI) groups based on their daily SI. The influence of SI on baPWV was analyzed using the multivariate logistic regression model. A total of 36324 subjects, aged (49.10 ± 12.57) years with a male to female ratio of 25934 : 10390, met the inclusion criteria and were enrolled. The average baPWV was (1527.73 ± 355.61) cm/s. Logistic regression analysis showed that after adjusting for other confounders, daily SI>10 g (high SI) was a risk factor for arterial stiffness (baPWV ≥1400 cm/s), with the odds ratio (95% confidence interval [CI]) of 1.17 (1.04-1.31). High SI is independently associated with arterial stiffness.

Associations of urinary sodium excretion with central hemodynamics and changes in vascular structure and function at high altitude

Research reports on associations of urinary sodium excretion with central hemodynamic parameters and vascular changes are quite limited in general or non‐hypertensive population. The purpose of the current study was to explore such associations in Chinese general Tibetans living at high altitude. This cross‐sectional study was conducted in Luhuo County, Ganzi Tibetan Autonomous Prefecture with average elevation of 3800 meters from December 2018 to January 2019. A total of 294 Tibetans were included in the current study. Twenty‐four hour urinary sodium excretion was estimated by second fasting spot urine in the morning using Kawasaki formula. Central hemodynamic parameters, including central systolic blood pressure (CSBP), central diastolic blood pressure (CDBP), central pulse pressure (CPP), central mean arterial pressure (CMAP), augmentation pressure (AP), and augmentation index standardized for heart rate of 75 (AIx₇₅), were evaluated using the SphygmoCor system. Vascular structures and functions were assessed by carotid intima media thickness (CIMT) test and brachial ankle pulse wave velocity (baPWV), respectively. Estimated mean 24h urinary sodium excretion of Tibetans in Luhuo County was 5.26±1.61 g. After adjustment, estimated 24h urinary sodium was positively associated with CSBP (β = 1.15, p = .008) and CPP (β = 0.87, p = .013). Line graph of means across urinary sodium quartiles showed that associations of 24 h urinary sodium excretion with AIx₇₅ and baPWV presented approximate “J” shape after controlling for confounders. Estimated 24 h sodium excretion was independently and positively associated with CSBP and CPP. Moreover, association between urinary sodium excretion and arterial elasticity, as evaluated by baPWV and AIx₇₅, presented “J” shape. Further studies are needed to verify J‐shaped association and “safe” zone of sodium intake.

Endogenous Mammalian Cardiotonic Steroids-A New Cardiovascular Risk Factor?-A Mini-Review

The role of endogenous mammalian cardiotonic steroids (CTS) in the physiology and pathophysiology of the cardiovascular system and the kidneys has interested researchers for more than 20 years. Cardiotonic steroids extracted from toads or plants, such as digitalis, have been used to treat heart disease since ancient times. CTS, also called endogenous digitalis-like factors, take part in the regulation of blood pressure and sodium homeostasis through their effects on the transport enzyme called sodium–potassium adenosine triphosphatase (Na/K-ATPase) in renal and cardiovascular tissue. In recent years, there has been increasing evidence showing deleterious effects of CTS on the structure and function of the heart, vasculature and kidneys. Understanding the role of CTS may be useful in the development of potential new therapeutic strategies.

Dietary Sodium Intake and Health Indicators: A Systematic Review of Published Literature between January 2015 and December 2019

As the science surrounding population sodium reduction evolves, monitoring and evaluating new studies on intake and health can help increase our understanding of the associated benefits and risks. Here we describe a systematic review of recent studies on sodium intake and health, examine the risk of bias (ROB) of selected studies, and provide direction for future research. Seven online databases were searched monthly from January 2015 to December 2019. We selected human studies that met specified population, intervention, comparison, outcome, time, setting/study design (PICOTS) criteria and abstracted attributes related to the study population, design, intervention, exposure, and outcomes, and evaluated ROB for the subset of studies on sodium intake and cardiovascular disease risks or indicators. Of 41,601 abstracts reviewed, 231 studies were identified that met the PICOTS criteria and ROB was assessed for 54 studies. One hundred and fifty-seven (68%) studies were observational and 161 (70%) focused on the general population. Five types of sodium interventions and a variety of urinary and dietary measurement methods were used to establish and quantify sodium intake. Five observational studies used multiple 24-h urine collections to assess sodium intake. Evidence mainly focused on cardiovascular-related indicators (48%) but encompassed an assortment of outcomes. Studies varied in ROB domains and 87% of studies evaluated were missing information on ≥1 domains. Two or more studies on each of 12 outcomes (e.g., cognition) not previously included in systematic reviews and 9 new studies at low ROB suggest the need for ongoing or updated systematic reviews of evidence on sodium intake and health. Summarizing evidence from assessments on sodium and health outcomes was limited by the various methods used to measure sodium intake and outcomes, as well as lack of details related to study design and conduct. In line with research recommendations identified by the National Academies of Science, future research is needed to identify and standardize methods for measuring sodium intake.

Effects of added salt reduction on central and peripheral blood pressure

BACKGROUND

Although the effects of salt intake reduction on casual blood pressure have been extensively studied in hypertensive individuals, data on reductions of added salt on arterial stiffness in both normotensive and prehypertensive subjects are scarce.

OBJECTIVE

To evaluate the effects of progressive reduction in added salt intake (from 6 grams to 4 grams per day) on peripheral and central blood pressure and arterial stiffness in normotensive, prehypertensive and hypertensive individuals.

METHODS

This was a single-blinded clinical trial with 13 weeks of follow-up. Normotensive (≤ 130/85 mmHg), prehypertensive (≥ 130 e < 139/≥ 85 e < 90 mmHg) and stage 1 hypertensive individuals (< 139/≥ 85 and < 90 mmHg) were assessed. Casual blood pressure measurements and ambulatory blood pressure monitoring were performed using the automated OMRON 705CP device, and central blood pressure was measured using the Sphygmocor®. Twenty-four-hour urinary sodium excretion and the amounts of added salt consumed were measured. Statistically significance level was set at p < 0.05 for all analysis.

RESULTS

A total of 55 participants (18 normotensive, 15 prehypertensive and 22 hypertensive), median age 48 years (IQR:39-54) were studied. The groups were not different in age or sex. No difference was observed in blood pressure or sodium excretion levels before and after the intervention. No significant changes in arterial stiffness parameters were observed.

CONCLUSION

The progressive reduction in added salt intake during a period of 13 weeks did not cause significant reductions in peripheral and central blood pressure. (Arq Bras Cardiol. 2020; 114(3):554-561).

Effect of dietary salt restriction on central blood pressure: A systematic review and meta-analysis of the intervention studies

Central blood pressure (cBP) is highly associated with cardiovascular risk. Although reduction of salt intake leads to lower peripheral blood pressure (BP), the studies on cBP provided inconsistent results. Therefore, we performed a systematic review and a meta-analysis of the available intervention trials of salt reduction on cBP values to reach definitive conclusions. A systematic search of the online databases available (up to December 2018) was conducted including the intervention trials that reported non-invasively assessed cBP changes after two different salt intake regimens. For each study, the mean difference and 95% confidence intervals were pooled using a random-effect model. Sensitivity, heterogeneity, publication bias, subgroup, and meta-regression analyses were performed. Fourteen studies met the pre-defined inclusion criteria and provided 17 cohorts with 457 participants with 1-13 weeks of intervention time. In the pooled analysis, salt restriction was associated with a significant reduction in augmentation index (9.3%) as well as central systolic BP and central pulse pressure. There was a significant heterogeneity among studies (I²  = 70%), but no evidence of publication bias. Peripheral BP changes seemed to partially interfere on the relationship between salt restriction and cBP. The results of this meta-analysis indicate that dietary salt restriction reduces cBP. This effect seems to be, at least in part, independent of the changes in peripheral BP.

Current Data on Dietary Sodium, Arterial Structure and Function in Humans: A Systematic Review

Background: Subclinical arterial damage (SAD) (arteriosclerosis, arterial remodeling and atheromatosis) pre-exists decades before cardiovascular disease (CVD) onset. Worldwide, sodium (Na) intake is almost double international recommendations and has been linked with CVD and death, although in a J-shape manner. Studies regarding dietary Na and major types of SAD may provide pathophysiological insight into the association between Na and CVD. Objectives: Systematic review of data derived from observational and interventional studies in humans, investigating the association between dietary Na with (i) atheromatosis (arterial plaques); (ii) arteriosclerosis (various biomarkers of arterial stiffness); (iii) arterial remodeling (intima–media thickening and arterial lumen diameters). Data sources: Applying the PRISMA criteria, the PubMed and Scopus databases were used. Results: 36 studies were included: 27 examining arteriosclerosis, four arteriosclerosis and arterial remodeling, three arterial remodeling, and two arterial remodeling and atheromatosis. Conclusions: (i) Although several studies exist, the evidence does not clearly support a clinically meaningful and direct (independent from blood pressure) effect of Na on arterial wall stiffening; (ii) data regarding the association of dietary Na with arterial remodeling are limited, mostly suggesting a positive trend between dietary Na and arterial hypertrophy but still inconclusive; (iii) as regards to atheromatosis, data are scarce and the available studies present high heterogeneity. Further state-of-the-art interventional studies must address the remaining controversies.

Relationship between 24-hour urinary sodium excretion and blood pressure in the adult population in Shandong, China

The main objective of this study was to determine baseline salt intake levels in a sample of the adult population of Shandong province and to establish the relationship between urinary sodium excretion and blood pressure. A total of 512 participants were recruited, and all the participants provided complete 24‐hour urine collections. Physical assessment and socioeconomic status of participants were collected at the same time. The mean 24‐hour urinary sodium excretion of all subjects was 228.0 ± 127.5 mmol/24 hours. Estimated salt intake was higher in obese subjects (17.6 ± 8.8 g/d) compared with overweight subjects (15.6 ± 8.0 g/d) and those with a normal BMI (13.9 ± 6.8 g/d). Likewise, urinary sodium excretion of hypertensive participants was dramatically higher than that of non‐hypertensive ones, the equivalent of 18.2 ± 9.1 g/d vs 13.3 ± 6.8 g/d. Urinary sodium was significantly associated with SBP (β = 1.08, P = .018) after adjustment for potential confounders. In summary, we found significantly high levels of salt intake in Shandong Province, particularly in obese and hypertension subjects. It is quite important to improve public education about reducing salt intake to control blood pressure among Shandong people.

Cardiotonic Steroids-A Possible Link Between High-Salt Diet and Organ Damage

High dietary salt intake has been listed among the top ten risk factors for disability-adjusted life years. We discuss the role of endogenous cardiotonic steroids in mediating the dietary salt-induced hypertension and organ damage.

Association of blood pressure with estimates of 24-h urinary sodium and potassium excretion from repeated single-spot urine samples

While the association between 24-h urinary sodium and potassium excretion with blood pressure is well established, the relationships of these ions to spot urine measurements are unclear. Our purpose is to assess the association between blood pressure and the estimated 24-h sodium and potassium excretion from repeated single-spot urine samples. Spot urine and blood pressure were collected annually during a 5-year period from 4360 Japanese workers with ages ranging from 19 to 55 years. Estimates of 24-h sodium and potassium excretion were based on Tanaka's formula. Overall, a single standard deviation increase in the estimated sodium excretion (36.5 mmol/day) was associated with a 1.3 mmHg higher systolic blood pressure and a 0.8 mmHg higher diastolic blood pressure (P < 0.001). A single standard deviation increase in estimated potassium excretion (8.9 mmol/day) was associated with a 1.1 mmHg lower systolic blood pressure and a 0.7 mmHg lower diastolic blood pressure (P < 0.001). As a combined measure of the excretion of both electrolytes, the estimated 24-h sodium-to-potassium ratio was positively associated with both blood pressures (P < 0.001). Associations of blood pressure with sodium and the sodium-to-potassium ratio increased with age and were stronger in men compared to women. Associations with potassium and the sodium-to-potassium ratio were stronger in individuals who were overweight. The findings provide evidence for an association between blood pressure and the estimated 24-h sodium and potassium excretion from repeated single-spot urine samples. As convenient measures of dietary intake for each electrolyte, repeated spot urine samples may be useful for assessing hypertension risk, especially in men, older individuals, and overweight individuals.

Dietary Sodium Restriction Reduces Arterial Stiffness, Vascular TGF-β-Dependent Fibrosis and Marinobufagenin in Young Normotensive Rats

High salt (HS) intake stimulates the production of marinobufagenin (MBG), an endogenous steroidal Na/K-ATPase ligand, which activates profibrotic signaling. HS is accompanied by a blood pressure (BP) increase in salt-sensitive hypertension, but not in normotensive animals. Here, we investigated whether HS stimulates MBG production and activates transforming growth factor-beta (TGF-β) profibrotic signaling in young normotensive rats, and whether these changes can be reversed by reducing salt to a normal salt (NS) level. Three-month old male Sprague–Dawley rats received NS for 4 and 8 weeks (0.5% NaCl; NS4 and NS8), or HS for 4 and 8 weeks (4% NaCl; HS4 and HS8), or HS for 4 weeks followed by NS for 4 weeks (HS4/NS4), n = 8/group. Systolic BP (SBP), pulse wave velocity (PWV), MBG excretion, aortic collagen 1α2, collagen 4α1 and TGF-β, Smad2, Smad3, Fli-1 mRNA, and total collagen abundance were measured at baseline (BL), and on weeks 4 and 8. Statistical analysis was performed using one-way ANOVA. SBP was not affected by HS (125 ± 5 and 126 ± 6 vs. 128 ± 7 mmHg, HS4 and HS8 vs. BL, p > 0.05). HS increased MBG (164 ± 19 vs. 103 ± 19 pmol/24 h/kg, HS4 vs. BL, p < 0.05) and PWV (3.7 ± 0.2 vs. 2.7 ± 0.2 m/s, HS4 vs. NS4, p < 0.05). HS8 was associated with a further increase in MBG and PWV, with an increase in aortic Col1a2 80%), Col4a1 (50%), Tgfb1 (30%), Smad2 (30%) and Smad3 (45%) mRNAs, and aortic wall collagen (180%) vs. NS8 (all p < 0.05). NS following HS downregulated HS-induced factors: in HS4/NS4, the MBG level was 91 ± 12 pmol/24 h/kg (twofold lower than HS8, p < 0.01), PWV was 3.7 ± 0.3 vs. 4.7 ± 0.2 m/s (HS4/NS4 vs. HS8, p < 0.05), aortic wall Tgfb1, Col1a2, Col4a1, Smad2, Smad3 mRNAs, and collagen abundance were reversed by salt reduction to the BL levels (p < 0.05). HS was associated with an activation of TGF-β signaling, aortic fibrosis and aortic stiffness accompanied by an MBG increase in the absence of SBP changes in young normotensive rats. The reduction of dietary salt following HS decreased MBG, PWV, aortic wall collagen and TGF-β. Thus, HS-induced aortic stiffness in normotensive animals occurred in the context of elevated MBG, which may activate SMAD-dependent TGF-β pro-fibrotic signaling. This data suggests that a decrease in salt consumption could help to restore aortic elasticity and diminish the risk of cardiovascular disease by reducing the production of the pro-fibrotic factor MBG.

Arterial stiffness, not systolic blood pressure, increases with age in native Papuan populations

Systolic blood pressure (SBP) and arterial stiffness are closely related and may behave reciprocally as cause or effect, interacting in a vicious cycle. Both SBP and arterial stiffness increase with age in populations in most developed countries. However, the age-related increase in SBP appears to be absent in indigenous populations, partially because of their lifelong low-sodium and high-potassium diets, whereas age-related arterial stiffening in these populations remains to be determined. We performed a field survey of the indigenous population of Soroba, a small village located in the central highlands of Papua, Indonesia. Blood pressure levels and brachial-ankle pulse wave velocity (baPWV) were measured using an automatic device. A total of 125 native Papuans 16-75 years of age (59% women) were included in this study. SBP and pulse pressure were not correlated with age. However, diastolic and mean arterial pressure levels increased with age. The prevalence of hypertension was 5% (n = 6; all women), and baPWV significantly increased with age. Compared with participants 45 years of age and older, those younger than 45 years had a higher body mass index (BMI) and spot urine sodium-to-potassium ratio but lower baPWV; however, SBP was not different between these age groups. Multivariate linear regression analysis revealed that SBP was independently associated with baPWV, sex and BMI but not with age; baPWV was independently associated with SBP, age, BMI, sex and heart rate. SBP and baPWV were closely related, but the age-related changes in these measurements differed in this highland Papuan population.

Marinobufagenin is related to elevated central and 24-h systolic blood pressures in young black women: the African-PREDICT Study

Marinobufagenin (MBG) is an endogenous steroidal α1-Na+K+-ATPase inhibitor. Because of its role in sodium handling, MBG has been associated with both antihypertensive and prohypertensive effects in normal physiology and pathology. MBG is positively associated with blood pressure in Dahl salt-sensitive rats exhibiting a similar hypertensive phenotype to black populations, characterized by impaired urinary Na+ excretion. However, clinical studies exploring blood pressure (BP)-related effects of MBG in black populations are scant. We determined whether the MBG/Na+ ratio (assessing the effectiveness of Na+ excretion resistance to MBG) is related to systolic BP (SBP) in young black men and women, compared to whites. We included 331 apparently healthy participants (20-30 years) (42.9% black, 43.8% men) on a habitual diet. We obtained 24-h and central SBP, and 24-h urinary Na+ and MBG levels. We found no ethnic differences in MBG, Na+ or MBG/Na+. MBG excretion correlated positively with Na+ excretion in all groups and to SBP in white men and black women (p ≤ 0.011). In black women only SBP related positively to MBG/Na+ in single and multi-variable adjusted regression models: central SBP (R2 = 0.26; ß = 0.28; p = 0.039), 24-h SBP (R2 = 0.46; ß = 0.30; p = 0.011), daytime (R2 = 0.38; ß = 0.28; p = 0.023) and nighttime SBP (R2 = 0.38; ß = 0.33; p = 0.009). In contrast, inverse associations of MBG/Na+ with nighttime SBP were evident in white women (r = -0.20; p = 0.038) but lost significance after multiple adjustments (R2 = 0.36; ß = -0.13; p = 0.12). We found independent positive associations of SBP with MBG/Na+ in black women. This data supports the concept that reduced MBG-mediated Na+ excretion can contribute to adverse hemodynamics.

The salt-taste threshold in untreated hypertensive patients

Background

The salt-taste threshold can influence the salt appetite, and is thought to be another marker of sodium intake. Many studies have mentioned the relationship between the sodium intake and blood pressure (BP). The aim of this study was to evaluate the relationship between the salt-taste threshold and urinary sodium excretion in normotensive and hypertensive groups.

Methods

We analyzed 199 patients (mean age 52 years, male 47.3%) who underwent 24-h ambulatory BP monitoring (ABPM). Hypertension was diagnosed as an average daytime systolic BP of ≥135 mmHg or diastolic BP of ≥85 mmHg by the ABPM. We assessed the salt-taste threshold using graded saline solutions. The salt-taste threshold, 24-h urinary sodium and potassium excretion, and echocardiographic data were compared between the control and hypertensive groups.

Results

The detection and recognition threshold of the salt taste did not significantly differ between the control and hypertensive groups. The 24-h urinary sodium excretion of hypertensive patients was significantly higher than that of the control group (140.9 ± 59.8 vs. 117.9 ± 57.2 mEq/day, respectively, p = 0.011). Also, the urinary sodium-potassium ratio was significantly higher in the hypertensive patients. There was no correlation between the salt-taste threshold and 24-h urinary sodium excretion.

Conclusions

The salt-taste threshold might not be related to the BP status as well as the 24-h urinary sodium excretion.