High salt intake and cardiovascular disease: is there a connection?

INSAF-HAS: a tool to select patients with hypertension for pharmaceutical care

OBJECTIVE

To develop and validate the content of a tool aimed to select patients with hypertension for pharmaceutical care, based on identification of individuals in greater need of attention.

METHODS

The tool was developed and assessed for face and content validity, which was carried out in three stages. Phase I consisted of comprehensive literature review, which prompted the development of the first version of the tool. Phase II consisted of validation by an expert panel. Phase III consisted of a pilot study with hypertensive patients and preparation of the final version of the instrument.

RESULTS

Literature review yielded 30 studies, out of which 13 factors associated with hypertension and cardiovascular disease control and complications were selected. Once the initial version of the tool named INSAF-HAS was obtained, four expert meetings were held, each leading to instrument improvement until a final consensus was reached. In the pilot study, INSAF-HAS was applied to 30 patients with a diagnosis of hypertension for applicability pretest; adjustments were made and the final version of INSAF-HAS obtained.

CONCLUSION

The INSAF-HAS tool developed in this study has face and content validity, and may contribute to the selection of patients with hypertension in greater need of pharmaceutical care services.

Monitoring protein structural changes and hydration in bovine meat tissue due to salt substitutes by Fourier transform infrared (FTIR) microspectroscopy

The objective of this study was to investigate the influence of NaCl and two salt substitutes, MgSO4 and KCl, in different concentrations (1.5, 6.0, and 9.0%) on meat proteins by using Fourier transform infrared (FTIR) microspectroscopy. Hydration properties and secondary structural properties of proteins were investigated by studying the amide I, amide II, and water regions (3500-3000 cm(-1)) in FTIR spectra. By applying multivariate analysis (PCA and PLSR), differences between samples according to salt concentration and salt type were found and correlated to spectral bands. The most distinctive differences related to salt type were obtained by using the water region. It was found that samples salted with MgSO4 exhibited hydration and subsequent denaturation of proteins at lower concentrations than those salted with NaCl. Samples salted with KCl brines showed less denaturation even at the 9.0% concentration. The FTIR results were further supported by water-binding capacity (WBC) measurements.

Blood pressure AsSAuLTed by the circadian clock

While Cry proteins are necessary for circadian rhythmicity, they now appear to play a seminal role in blood pressure regulation. In a recent issue of Nature Medicine, Doi et al., 2009 show how the circadian clock may use Cry proteins to protect from salt-sensitive hypertension.

Inflammation and Oxidative Stress Markers by Pentoxifylline Treatment in Rats with Chronic Renal Failure and High Sodium Intake

BACKGROUND

Inflammation is a risk factor for mortality in patients with chronic renal failure (CRF). Prevention of extracellular fluid volume expansion and the use of certain drugs such as pentoxifylline (PF) may reduce inflammation and oxidative stress. The aim of this study is to analyze the effect of dietary sodium and PF treatment on the levels of inflammation and oxidative stress markers in rats with CRF.

METHODS

CRF was induced in rats by 5/6 nephrectomy. Different groups of rats with CRF received low sodium (LNa, 0.01% sodium chloride [NaCl] in the diet), normal sodium (NNa, 0.05% NaCl in the diet), or high sodium diet (HNa, as in NNa plus 0.015% NaCl in the drinking water). An additional group received HNa plus PF treatment (25 mg/kg in the drinking water) for 60 days. Circulating creatinine, tumor necrosis factor alpha (TNF-alpha), nitrites, thiols, malondialdehyde (MDA), and advanced oxidation protein products (AOPP) were measured.

RESULTS

Higher sodium intake was associated with higher serum creatinine levels (median; interquartile range), LNa, 1.255; 0.715, NNa, 1.305; 0.495, HNa, 2.015; 1.115 mg/dL (p < 0.05), TNF-alpha levels, LNa, 2.7; 23.6, NNa, 36.7; 47.7, HNa, 263.7; 126.5 pg/mL, and AOPP, LNa, 31.72; 7.55, NNa, 45.89; 9.38, HNa, 60.41; 37.42 microg/mL. MDA was not modified by sodium intake. PF treatment decreased serum TNF-alpha (151.7 pg/mL, p < 0.5) and AOPP (49.83 micromol/L, p < 0.03), and increased nitrites and thiols levels when compared with HNa rats.

CONCLUSIONS

High sodium intake increases the serum concentration of inflammation and oxidative stress markers; these changes are prevented by PF treatment.

A potential role for the endothelin ETA receptor in salt-sensitive hypertension of the proANP gene-disrupted mouse

We have previously shown that the partial disruption of the gene for atrial natriuretic peptide (ANP) results in a salt-sensitive phenotype. The present study examined the possibility that alterations in either the ANP natriuretic pathway or endothelin (ET) system in the kidney of the salt-challenged ANP +/- mouse was responsible for its salt-sensitive phenotype. Plasma ANP levels and renal cGMP activity were increased in response to a salt load in both ANP +/+ and +/- mice. However, the mRNA expression of proANP was found to be increased only in the ANP +/- kidney along with its guanylyl cyclase-linked receptor, NPRA; the upregulation of NPRA mRNA was limited to the renal medulla. This suggests that the renal ANP pathway remains capable of responding to a salt load in the ANP +/- animal, but may be compensating for other dysfunctional pathways. We also report a significant increase in renal ET-1 mRNA and ETA receptor protein expression in medulla and cortex of the salt-treated, ANP +/- mouse, but not its wild-type counterpart. In fact, ETA expression decreased in the renal cortex of the ANP +/+ salt-treated animal. The ETB receptor expression was not affected by diet in either genotype. We hypothesize that the salt-sensitive hypertension in the ANP +/- mouse is exacerbated, and possibly driven by the vasoconstrictive effects resulting from an upregulated ET-1/ETA pathway.

Effects of high sodium intake diet on the vascular reactivity to phenylephrine on rat isolated caudal and renal vascular beds: Endothelial modulation

High salt intake is involved in the genesis of hypertension and vascular changes in salt-sensitive patients. Although many mechanisms have been proposed, the underlying mechanisms of these alterations in healthy rats are not completely elucidated. The aim of this study was to investigate if male Wistar rats fed a high salt diet, NaCl 1.8% in drinking water for 4 weeks, develop changes in the pressor reactivity of isolated tail and renal vascular beds. Salt treatment increased mean arterial pressure (SALT = 124 +/- 2.2 vs. CT = 111 +/- 3.9 mmHg; p < 0.01) and urinary sodium excretion in the absence of changes in sodium plasma levels. Pressor reactivity was generated in isolated tail and kidney vascular beds as dose-response curves to phenylephrine (PHE = 0.01 to 300 microg). SALT increased the reactivity (E(max): SALT = 378 +/- 15.8 vs. CT = 282 +/- 10 mmHg; p < 0.01) without changing the sensitivity (pD(2)) to PHE in the tail vascular bed. However, these parameters did not change in the renal bed. In subsequent studies on the isolated caudal vascular bed, we found that endothelial damage, but not L-NAME (100 microM) or indomethacin (10 microM), abolished the increment in E(max) to PHE induced by SALT. On the other hand, losartan (100 microM) reduced E(max) in SALT to CT values. Additionally, local angiotensin-converting enzyme activity in segments from tail artery increased by 95%. In conclusion, 4 weeks of high salt diet increases blood pressure and induces specific territorial vascular changes in response to PHE. Results also suggest that the increment in E(max) in the tail vascular bed from SALT rats was endothelium-dependent and was mediated by the activation of the local renin-angiotensin system.