Hyperosmolar sodium chloride, p38 mitogen activated protein and cytokine-mediated inflammation

Edelman Revisited: Concepts, Achievements, and Challenges

The key message from the 1958 Edelman study states that combinations of external gains or losses of sodium, potassium and water leading to an increase of the fraction (total body sodium plus total body potassium) over total body water will raise the serum sodium concentration ([Na]_S), while external gains or losses leading to a decrease in this fraction will lower [Na]_S. A variety of studies have supported this concept and current quantitative methods for correcting dysnatremias, including formulas calculating the volume of saline needed for a change in [Na]_S are based on it. Not accounting for external losses of sodium, potassium and water during treatment and faulty values for body water inserted in the formulas predicting the change in [Na]_S affect the accuracy of these formulas. Newly described factors potentially affecting the change in [Na]_S during treatment of dysnatremias include the following: (a) exchanges during development or correction of dysnatremias between osmotically inactive sodium stored in tissues and osmotically active sodium in solution in body fluids; (b) chemical binding of part of body water to macromolecules which would decrease the amount of body water available for osmotic exchanges; and (c) genetic influences on the determination of sodium concentration in body fluids. The effects of these newer developments on the methods of treatment of dysnatremias are not well-established and will need extensive studying. Currently, monitoring of serum sodium concentration remains a critical step during treatment of dysnatremias.

Crosstalk between phosphorylation and ubiquitination is involved in high salt-induced WNK4 expression

With no lysine 4 (WNK4) is a serine/threonine kinase, which is expressed in the kidney and associated with salt-sensitive hypertension. However, how salt regulates WNK4 remains unclear. In the present study, the C57BL/6 mice and HEK293 cells were treated with high salt and the expression of WNK4 protein and its ubiquitination and phosphorylation levels were detected. Western blotting demonstrated that WNK4 expression was significantly increased in high salt-treated mice and cells. Meanwhile, co-immunoprecipitation analysis demonstrated that the ubiquitination of WNK4 was decreased under high-salt simulation. It was also identified that the Lys-1023 site was the most important ubiquitination site for WNK4, and it was found that phosphorylation at the Ser-1022 site was a prerequisite for ubiquitination. These results suggested that there was crosstalk between phosphorylation and ubiquitination in the WNK4 protein, and high salt may downregulate its phosphorylation and, in turn, decrease its ubiquitination, leading to a decrease in WNK4 degradation. This eventually resulted in an increase in the abundance of WNK4 protein.

Serum high-sensitive C-reactive protein is associated with dietary intakes in diabetic patients with and without hypertension: a cross-sectional study

Background Serum high-sensitive C-reactive protein (hs-CRP) concentrations independently predict the development of diabetes, metabolic syndrome and cardiovascular disease. However, the impact of dietary factors on serum high-sensitive C-reactive protein concentrations in diabetic patients has received limited attention. We aimed to investigate the association between dietary factors and high-sensitive C-reactive protein , among diabetic patients with and without hypertension and healthy subjects. Methods In this cross-sectional study, diabetics with ( n = 325) and without hypertension ( n = 599) and healthy individuals ( n = 1220) were recruited in Mashhad, Iran. Dietary intake was assessed by 24-h recall. Biochemical parameters including serum high-sensitive C-reactive protein were measured using standard protocols. Stepwise multiple regression analysis was used to predict whether serum high-sensitive C-reactive protein concentration was associated with dietary constituents. Results High-sensitive C-reactive protein was significantly higher among hypertensive and non-hypertensive diabetic patients compared with healthy subjects ( P < 0.001). The dietary intake of zinc + 6.4% and calcium -3.4% and body mass index +3.9% explained approximately 13.7% of the variation in serum high-sensitive C-reactive protein among diabetic hypertensive patients. Approximately 9.7% of the variation in serum high-sensitive C-reactive protein in diabetic non-hypertensive patients could be explained by body mass index, and intake of sodium, iron and cholesterol. In the healthy subjects, approximately 4.4% of the total variation in serum high-sensitive C-reactive protein concentration could be explained by cholesterol consumption and waist circumference. Conclusion Serum high-sensitive C-reactive protein concentrations were found to be a significant predictor for hypertensive and non-hypertensive diabetic subjects. There was a significant association between dietary factors include zinc, iron, sodium and cholesterol and serum high-sensitive C-reactive protein, while there was an inverse association between dietary calcium and serum high-sensitive C-reactive protein in diabetic hypertensive individuals.

Effect of dialysate sodium reduction on body water volume, blood pressure, and inflammatory markers in hemodialysis patients--a prospective randomized controlled study

Accumulating evidence suggests an association between body volume overload and inflammation in chronic kidney diseases. The purpose of this study was to evaluate the effect of dialysate sodium concentration reduction on extracellular water volume, blood pressure (BP), and inflammatory state in hemodialysis (HD) patients. In this prospective controlled study, adult patients on HD for at least 90 days and those with C-reactive protein (CRP) levels ≥ 0.7 mg/dL were randomly allocated into two groups: group A, which included 29 patients treated with reduction of dialysate sodium concentration from 138 to 135 mEq/L; and group B, which included 23 HD patients not receiving dialysate sodium reduction (controls). Of these, 20 patients in group A and 18 in group B completed the protocol study. Inflammatory, biochemical, hematological, and nutritional markers were assessed at baseline and after 8 and 16 weeks. Baseline characteristics were not significantly different between the two groups. Group A showed a significant reduction in serum concentrations of tumor necrosis factor-α, and interleukin-6 over the study period, while the BP and extracellular water (ECW) did not change. In Group B, there were no changes in serum concentrations of inflammatory markers, BP, and ECW. Dialysate sodium reduction is associated with attenuation of the inflammatory state, without changes in the BP and ECW, suggesting inhibition of a salt-induced inflammatory response.

Skepinone-L is a selective p38 mitogen-activated protein kinase inhibitor

Until now, a lack of inhibitors with high potency and selectivity in vivo has hampered investigation of the p38 mitogen-activated protein kinase (MAPK) signaling pathway. We describe the design of skepinone-L, which is, to our knowledge, the first ATP-competitive p38 MAPK inhibitor with excellent in vivo efficacy and selectivity. Therefore, skepinone-L is a valuable probe for chemical biology research, and it may foster the development of a unique class of kinase inhibitors.

High-salt diet increases plasma adiponectin levels independent of blood pressure in hypertensive rats: the role of the renin-angiotensin-aldosterone system

BACKGROUND

High sodium intake is associated with increased risk of end-organ damage, independent of blood pressure (BP) levels. The protective peptide adiponectin may play a role in the pathogenesis of hypertension and particularly in salt-loaded conditions. Furthermore, increased adiponectin levels were observed in salt-loaded conditions. However, there is little information on the direct effect of high-salt diet on plasma adiponectin. The aim of the present study was to examine the effect of high-salt diet on adiponectin levels in Sprague-Dawley rats and explore the mechanisms that regulate adiponectin levels under salt loading.

METHODS

Sprague-Dawley rats were fed either standard chow diet or medium or high sodium diet for 5 weeks. BP and plasma adiponectin were measured at baseline and during the study. In additional studies the same protocol was repeated with the addition of clonidine, telmisartan, hydralazine or eplerenone.

RESULTS

High-salt diet increased systolic BP, suppressed plasma aldosterone levels and attenuated body weight gain. Five weeks of salt loading increased plasma adiponectin levels in a dose-dependent manner (medium salt and high salt were 47 and 93% higher than control, respectively, P < 0.05). Hydralazine and clonidine attenuated salt-induced BP increase but did not attenuate the increase in adiponectin levels whereas, telmisartan, an angiotensin receptor blocker, and eplerenone, an aldosterone blocker, attenuated both the increase in BP and in adiponectin levels.

CONCLUSIONS

High salt intake increases adiponectin levels independent of the increase in BP. This effect is mediated through the renin-angiotensin-aldosterone system.