Sodium intake is associated with parasympathetic tone and metabolic parameters in mild hypertension

Association between urinary sodium and circulating lipid levels: a Mendelian randomization study

Background

Urinary sodium was indicated to be associated with dyslipidemia, but inconsistent conclusions for this association exist across the present observational studies.

Objectives

This study aimed to evaluate the causal association between urinary sodium and circulating lipid levels [low-density lipoprotein cholesterol (LDL-C), triglycerides, and high-density lipoprotein cholesterol (HDL-C)] through Mendelian randomization.

Methods

Univariable Mendelian randomization (UVMR) and multivariable Mendelian randomization (MVMR) with pleiotropy-resistant methods were performed. Data for urinary sodium were obtained from the genome-wide association study (GWAS) from 446,237 European individuals. Data for lipid profiles were extracted from GWAS based on the UK Biobank (for the discovery analysis) and the Global Lipids Genetics Consortium (for the replication analysis).

Results

In the discovery analysis, UVMR provided evidence that per 1-unit log-transformed genetically increased urinary sodium was associated with a lower level of HDL-C level (beta = -0.32; 95% CI: -0.43, -0.20; p = 7.25E-08), but not with LDL-C and triglycerides. This effect was still significant in the further MVMR when considering the effect of BMI or the other two lipid contents. In contrast, higher genetically predicted triglycerides could increase urinary sodium in both UVMR (beta = 0.030; 95% CI: 0.020, -0.039; p = 2.12E-10) and MVMR analyses (beta = 0.029; 95% CI: 0.019, 0.037; p = 8.13E-10). Similar results between triglycerides and urinary sodium were found in the replication analysis.

Conclusion

Increased urinary sodium may have weak causal effects on decreased circulating HDL-C levels. Furthermore, genetically higher triglyceride levels may have independent causal effects on increased urinary sodium excretion.

Autonomic Nervous System Regulation of Epicardial Adipose Tissue: Potential Roles for Regulator of G Protein Signaling-4

The epicardial adipose tissue (EAT) or epicardial fat is a visceral fat depot in the heart that contains intrinsic adrenergic and cholinergic nerves, through which it interacts with the cardiac sympathetic (adrenergic) and parasympathetic (cholinergic) nervous systems. These EAT nerves represent a significant source of several adipokines and other bioactive molecules, including norepinephrine, epinephrine, and free fatty acids. The production of these molecules is biologically relevant for the heart, since abnormalities in EAT secretion are implicated in the development of pathological conditions, including coronary atherosclerosis, atrial fibrillation, and heart failure. Sympathetic hyperactivity and parasympathetic (cholinergic) derangement are associated with EAT dysfunction, leading to a variety of adverse cardiac conditions, such as heart failure, diastolic dysfunction, atrial fibrillation, etc.; therefore, several studies have focused on exploring the autonomic regulation of EAT as it pertains to heart disease pathogenesis and progression. In addition, Regulator of G protein Signaling (RGS)-4 is a protein with significant regulatory roles in both adrenergic and muscarinic receptor signaling in the heart. In this review, we provide an overview of the autonomic regulation of EAT, with a specific focus on cardiac RGS4 and the potential roles this protein plays in this regulation.

Autonomic nervous system activity changes in patients with hypertension and overweight: role and therapeutic implications

The incidence and prevalence of hypertension is increasing worldwide, with approximately 1.13 billion of people currently affected by the disease, often in association with other diseases such as diabetes mellitus, chronic kidney disease, dyslipidemia/hypercholesterolemia, and obesity. The autonomic nervous system has been implicated in the pathophysiology of hypertension, and treatments targeting the sympathetic nervous system (SNS), a key component of the autonomic nervous system, have been developed; however, current recommendations provide little guidance on their use. This review discusses the etiology of hypertension, and more specifically the role of the SNS in the pathophysiology of hypertension and its associated disorders. In addition, the effects of current antihypertensive management strategies, including pharmacotherapies, on the SNS are examined, with a focus on imidazoline receptor agonists.

High-Salt Intake Reduces Apomorphine-Induced Penile Erection and Increases Neurally Mediated Contractile Responses of the Cavernosal Smooth Muscle in Rats

BACKGROUND

This study was designed to evaluate whether overconsumption of NaCl, a well-known risk factor for hypertension, leads to erectile dysfunction in rodents.

METHODS

Male Wistar rats received regular chow (control group) or 4% NaCl chow for 24 weeks and were subjected to blood pressure measurement and apomorphine-induced erection. Moreover, cavernosal strips from both the control and 4% NaCl groups were evaluated in organ baths.

RESULTS

Animals subjected to 4% NaCl chow did not develop hypertension but presented a significant reduction in the total number of erections following apomorphine administration as compared with the control group. The addition of high KCl or phenylephrine resulted in similar contractile responses in the corpus cavernosal strips from both the control and 4% NaCl groups. However, electrical field stimulation-induced contraction was significantly enhanced in cavernosal strips from animals exposed to 4% NaCl. Incubation of Y-27632, but not of atropine and Nω-nitro-l-arginine methyl ester (L-NAME), entirely prevented the potentiation of the contractile responses evoked by electrical stimulation. The enhanced contractile responses evoked by electrical stimulation found in the high-salt group were also avoided in the absence of extracellular calcium. Concentration-response curves of CaCl2 revealed augmented contractility in response to extracellular calcium in cavernosal strips from the 4% NaCl-treated rats, compared with control samples.

CONCLUSIONS

A high-salt diet alone rendered the animals less responsive to apomorphine-induced penile erection and enhanced neurally mediated contractile responses in the corpus cavernosum, a clear indication that overconsumption of sodium can lead to erectile dysfunction even without the development of hypertension.

The non-neuronal cholinergic system in the heart: A comprehensive review

The autonomic influences on the heart have a ying-yang nature, albeit oversimplified, the interplay between the sympathetic and parasympathetic system (known as the cholinergic system) is often complex and remain poorly understood. Recently, the heart has been recognized to consist of neuronal and non-neuronal cholinergic system (NNCS). The existence of cardiac NNCS has been confirmed by the presence of cholinergic markers in the cardiomyocytes, which are crucial for synthesis (choline acetyltransferase, ChAT), storage (vesicular acetylcholine transporter, VAChT), reuptake of choline for synthesis (high-affinity choline transporter, CHT1) and degradation (acetylcholinesterase, AChE) of acetylcholine (ACh). The non-neuronal ACh released from cardiomyocytes is believed to locally regulate some of the key physiological functions of the heart, such as regulation of heart rate, offsetting hypertrophic signals, maintenance of action potential propagation as well as modulation of cardiac energy metabolism via the muscarinic ACh receptor in an auto/paracrine manner. Apart from this, several studies have also provided evidence for the beneficial role of ACh released from cardiomyocytes against cardiovascular diseases such as sympathetic hyperactivity-induced cardiac remodeling and dysfunction as well as myocardial infarction, confirming the important role of NNCS in disease prevention. In this review, we aim to provide a fundamental overview of cardiac NNCS, and information about its physiological role, regulatory factors as well as its cardioprotective effects. Finally, we propose the different approaches to target cardiac NNCS as an adjunctive treatment to specifically address the withdrawal of neuronal cholinergic system in cardiovascular disease such as heart failure.

Glomerular Density in Biopsy-Proven Hypertensive Nephrosclerosis

BACKGROUND

Previous autopsy studies suggested that a reduced nephron number is associated with increased risk of hypertension and chronic kidney disease. However, the significance of the nephron number estimated from a renal biopsy in patients with hypertensive nephrosclerosis (HNS) has not yet been elucidated.

METHODS

In this cross-sectional study, we examined the clinicopathological findings of biopsy-proven HNS patients with preserved renal function (estimated glomerular filtration rate ≥ 60 ml/min/1.73 m(2)). The glomerular density (GD; the number of glomeruli per total renal cortical area) in biopsy specimens was evaluated as a surrogate of the nephron number. Renal biopsies from kidney transplant donors were used as healthy controls.

RESULTS

A total of 58 HNS patients were enrolled. The GD value in the HNS patients was low compared with those in the kidney transplant donors (2.0 vs. 3.2 /mm(2)). These differences remained significant when globally sclerotic glomeruli were included in the calculation of the GD. Of note, the GD in HNS patients with overt proteinuria (≥1 g/day) was significantly lower than that of HNS patients with mild proteinuria (<1g/day; 1.8 vs. 2.2/mm(2), P = 0.014). In contrast, other histopathological parameters, including the severity of global glomerulosclerosis, interstitial fibrosis/tubular atrophy and arterial and arteriole lesions were comparable between the 2 HNS subgroups. In addition, the GD was identified as a factor that was associated with the amount of urinary protein excretion at biopsy, independent of other clinicopathological factors.

CONCLUSIONS

These results suggest that a low GD is a renal histological characteristic of HNS patients, especially those with overt proteinuria.

A1H NMR-based metabonomic investigation of time-dependent metabolic trajectories in a high salt-induced hypertension rat model

The time-dependent metabolic profiles in urine, plasma and feces of salt-fed hypertensive rats were systematically investigated using NMR-based metabonomics.

Association between glutathione S-transferase M1 polymorphism and urinary sodium excretion in a Brazilian population

BACKGROUND

Null genotypes of glutathione S-transferase (GST) exhibit the absence of enzymatic activity and are associated with increased cardiovascular risk. Recent reports have related both lower and higher urinary sodium excretion (USE) to higher cardiovascular risk. Here we investigate the impact of GSTM1 and GSTT1-null polymorphisms on USE in a Brazilian population.

METHODS

We cross-sectionally evaluated 1,308 subjects from the city of Vitoria, Brazil, based on clinical history, physical examination, anthropometry, analysis of laboratory parameters, measurement of USE, and GST polymorphisms genotyping.

RESULTS

The frequency of GST M1, T1, and double-deletion polymorphisms was 51%, 22%, and 11%, respectively. Individuals with the GSTM1-null genotype had lower USE than those with the non-null genotype (92.1±52.3 vs. 102.8 ± 6 0.7 mEq/12h; P < 0.001). Linear regression analysis adjusted for confounding factors revealed that the GSTM1-null genotype was independently associated with USE (P = 0.001). In addition, diastolic blood pressure and triglyceride levels were higher in GSTM1-null individuals than in non-null individuals in the highest tertile of USE. Finally, the presence of GSTT1-null or double-deleted genotypes did not influence USE or affect the interactions between USE and the variables studied.

CONCLUSIONS

Deletion of GSTM1 was associated with low USE and modulated the interaction between sodium intake and blood pressure in Brazilian subjects. These novel findings may provide a new unexplored link between sodium regulation and GST homeostasis.

Association of sodium and potassium intake with ventricular arrhythmic burden in patients with essential hypertension

BACKGROUND

Hypertensive populations suffer from an increased susceptibility to ventricular arrhythmias and sudden cardiac death. A high-salt diet appears to be a major factor involved in cardiovascular complications in hypertension. We examined the relationship between dietary salt and potassium, as indicated by urinary sodium (UNa), urinary potassium (UK), and urinary sodium/potassium ratio (UNa/K), and the arrhythmic burden in patients with essential hypertension.

METHODS

We included 255 consecutive adult patients with well-controlled hypertension who were being followed in the hypertension outpatient clinic of a university tertiary hospital and complained of episodes of atypical chest pain and/or palpitations. All underwent 24-hour ambulatory electrocardiograph monitoring and their UNa, UK, and UNa/K ratio from 24-hour urinary excretion specimens were evaluated.

RESULTS

No significant correlation was found between premature supraventricular contractions and the parameters that were examined. However, the percentage of premature ventricular contractions (PVC%) showed a weak positive association with UNa (r = 0.2; P = .001) and a moderate negative association with UK (r = -0.396; P < .001). The partial correlation coefficient of PVC% with the UNa/UK ratio remained significant even after controlling for left ventricular mass index (r = 0.437; P < .001).

CONCLUSIONS

A higher UNa/UK excretion ratio is significantly associated with PVCs, indicating an increased susceptibility to ventricular arrhythmias even among hypertensives with well-controlled blood pressure. Our findings reinforce recommendations for dietary interventions in those populations.

Favourable effects of the Dietary Approaches to Stop Hypertension diet on glucose tolerance and lipid profiles in gestational diabetes: a randomised clinical trial

Although gestational diabetes mellitus (GDM) is associated with an increased risk of maternal and neonatal morbidity, there is no consensus as to the optimal approach of nutritional management in these patients. The present study was designed to assess the effect of the Dietary Approaches to Stop Hypertension (DASH) eating plan on glucose tolerance and lipid profiles of pregnant women with GDM. The present randomised controlled clinical trial was performed among thirty-four women diagnosed with GDM at 24–28 weeks of gestation. Subjects were randomly assigned to consume either the control diet (n 17) or the DASH eating pattern (n 17) for 4 weeks. The control diet was designed to contain 45–55 % carbohydrates, 15–20 % protein and 25–30 % total fat. The macronutrient composition of the DASH diet was similar to the control diet; however, the DASH diet was rich in fruits, vegetables, whole grains and low-fat dairy products, and contained lower amounts of saturated fats, cholesterol and refined grains with a total of 2400 mg Na/d. Fasting blood samples were taken at baseline and after 4 weeks of intervention to measure fasting plasma glucose, glycated Hb (HbA1c) and lipid profiles. Participants underwent a 3 h oral glucose tolerance tests and blood samples were collected at 60, 120 and 180 min to measure plasma glucose levels. Adherence to the DASH eating pattern, compared with the control diet, resulted in improved glucose tolerance such that plasma glucose levels reduced at 60 ( − 1·86 v. − 0·45 mmol/l, Pgroup= 0·02), 120 ( − 2·3 v. 0·2 mmol/l, Pgroup= 0·001) and 180 min ( − 1·7 v. 0·22 mmol/l, Pgroup= 0·002) after the glucose load. Decreased HbA1c levels ( − 0·2 v. 0·05 %, Pgroup= 0·001) was also seen in the DASH group compared with the control group. Mean changes for serum total ( − 0·42 v. 0·31 mmol/l, Pgroup= 0·01) and LDL-cholesterol ( − 0·47 v. 0·22 mmol/l, Pgroup= 0·005), TAG ( − 0·17 v. 0·34 mmol/l, Pgroup= 0·01) and total:HDL-cholesterol ratio ( − 0·6 (sd 0·9) v. 0·3 (sd 0·8), Pgroup= 0·008) were significantly different between the two diets. Additionally, consumption of the DASH diet favourably influenced systolic blood pressure ( − 2·6 v. 1·7 mmHg, Pgroup= 0·001). Mean changes of fasting plasma glucose ( − 0·29 v. 0·15 mmol/l, Pgroup= 0·09) were non-significant comparing the DASH diet with the control diet. In conclusion, consumption of the DASH eating pattern for 4 weeks among pregnant women with GDM resulted in beneficial effects on glucose tolerance and lipid profiles compared with the control diet.