Decreasing dietary sodium while following a self-selected potassium-rich diet reduces blood pressure

Reducing dietary sodium reduces blood pressure (BP), a major risk factor for cardiovascular disease, but few studies have specifically examined the effect on BP of altering dietary sodium in the context of a high potassium diet. This randomized, crossover study compared BP values in volunteer subjects self-selecting food intake and consuming low levels of sodium (Na+; 50 mmol/d) with those consuming high levels of sodium (> or =20 mmol/d), in the context of a diet rich in potassium (K+). Sodium supplementation (NaSp) produced the difference in Na+ intake. Subjects (n = 108; 64 women, 44 men; 16 on antihypertensive therapy) had a mean age of 47.0 ± 10.1 y. Subjects were given dietary advice to achieve a low sodium (LS) diet with high potassium intake (50 mmol Na+/d, >80 mmol K+/d) and were allocated to NaSp (120 mmol Na+/d) or placebo treatment for 4 wk before crossover. The LS diet decreased urinary Na+ from baseline, 138.7 ± 5.3 mmol/d to 57.8 ± 3.8 mmol/d (P < 0.001). The NaSp treatment returned urinary Na+ to baseline levels 142.4 ± 3.7 mmol/d. Urinary K+ increased from baseline, 78.6 ± 2.3 to 86.6 ± 2.1 mmol/d with the LS diet and to 87.1 ± 2.1 mmol/d with NaSp treatment (P < 0.001). The LS diet reduced home systolic blood pressure (SBP) by 2.5 ± 0.8 mm Hg (P = 0.004), compared with the NaSp treatment. Hence, reducing Na+ intake from 140 to 60 mmol/d significantly decreased home SBP in subjects dwelling in a community setting who consumed a self-selected K+-rich diet, and this dietary modification could assist in lowering blood pressure in the general population.

Effect of a low sodium DASH diet, including red meat on blood pressure in post-menopausal women

Background – The DASH type dietary pattern which consists of high fruit, vegetable and dairy products and low saturated fat, is “base-producing” but restricts red meat with no clear justification.
Objective – To compare the BP-lowering effect of Vitality diet (VD), a moderately low sodium, “base” producing modified DASH diet, containing 6 serves/week of lean red meat to a “ high carbohydrate, low fat diet (HCLF diet), with a higher dietary acid load in post-menopausal women.
Design – Ninety-five hypertensive post-menopausal women (46 VD and 49 HCLF) completed a 14-wk randomised parallel study. Home BP was measured daily. Repeat 24-h dietary records and 24-h urine samples were collected fortnightly. Dietary acid load, expressed as potential renal acid load (PRAL), was calculated from nutrient intakes.
Outcomes – During the intervention, the VD group had an average daily consumption of 85 g cooked red meat. They had a mean (± SEM) reduction of 38 ± 7 mmol/d in urinary sodium excretion (P <0.0001), and a 7 ± 4 mmol/d increase in urinary potassium (P = 0.0681), with an estimated 23.1± 2.3 mEq/d lower PRAL than the HCLF group (P <0.0001). The fall in systolic pressure in the VD group tended to be greater by 3 ± 2 mmHg (P = 0.08) than the fall in systolic pressure seen with the HCLF diet. A greater BP-lowering effect of VD was observed among those taking anti-hypertensive medication (n = 17) with a greater 5.5 ± 2.7 mm Hg (P = 0.0518) reduction of systolic BP and greater reduction in diastolic BP by 3.6 ± 1.7 mm Hg (P = 0.0388) compared to the HCLF diet. However, no relationship between BP and PRAL was observed.
Conclusions – A low sodium DASH type dietary pattern with the inclusion of lean red meat was effective in reducing BP in post-menopausal women, particularly in those taking anti-hypertensive medication. This dietary pattern could be recommended for this group who are at increased risk of cardiovascular disease.
This study was funded by Meat & Livestock Australia.

Dietary fiber, potassium, magnesium and calcium in relation to the risk of preeclampsia

To explore the relation between preeclampsia risk and maternal intake of dietary fiber, potassium, magnesium and calcium. STUDY DESIGN: We conducted a case-control study of 172 preeclamptics and 339 normotensive controls. Maternal dietary intake was assessed using a food frequency questionnaire. Logistic regression procedures were used to estimate the association between each dietary factor and preeclampsia risk. RESULTS: Fiber intake was inversely associated with the risk of preeclampsia. When extreme quartiles of total fiber intake were compared, the odds ratio (OR) for preeclampsia was 0.46 (95% confidence interval [CI] 0.23-0.92). The multivariate OR for preeclampsia for women in the top quartile of potassium intake (>4.1 g/d) versus the lowest quartile (<2.4 g/d) was 0.49 (95% CI 0.24-0.99). There was some evidence of a reduced risk of preeclampsia with a high intake of magnesium and calcium, though these results were not statistically significant. Intake of fruits and vegetables, low-fat dairy products, total cereal and dark bread were each associated with a reduced risk of preeclampsia. CONCLUSION: Our results support previous reports that suggest that diets high in fiber and potassium are associated with a reduced risk of hypertension. Maternal intake of recommended amounts of foods rich in fiber, potassium and other nutrients may reduce the risk of preeclampsia.

Design and analysis of a low actuation voltage electrowetting-on-dielectric device

This paper presents an Electrowetting-on-Dielectric (EWOD) device with optimized insulating layers operated by low actuation voltage. The device consists of an electrode array on a silicon substrate, covered by a dielectric layer and a hydrophobic layer. To characterize the performance of the device, simulations are performed for the dielectric layer of Sio₂ and the hydrophobic layer of Sio₂, Su-8 and Parylene C at different voltages. The volume finite difference approach of the Coventorware software was used to carry out the simulations. Two different molar of di-ionized water droplet were considered in the simulations. It was observed that the device having the Sio₂ dielectric layer and the Parylene C hydrophobic layer moved the 1M KCL (potassium chloride) droplet at the actuation voltage of 25V.

Potassium channel modulation by a toxin domain in matrix metalloprotease

Peptide toxins found in a wide array of venoms block K+ channels, causing profound physiological and pathological effects. Here we describe the first functional K+ channel-blocking toxin domain in a mammalian protein. MMP23 (matrix metalloprotease 23) contains a domain (MMP23TxD) that is evolutionarily related to peptide toxins from sea anemones. MMP23TxD shows close structural similarity to the sea anemone toxins BgK and ShK. Moreover, this domain blocks K+ channels in the nanomolar to low micromolar range (Kv1.6 > Kv1.3 > Kv1.1 = Kv3.2 > Kv1.4, in decreasing order of potency) while sparing other K+ channels (Kv1.2, Kv1.5, Kv1.7, and KCa3.1). Full-length MMP23 suppresses K+ channels by co-localizing with and trapping MMP23TxD-sensitive channels in the ER. Our results provide clues to the structure and function of the vast family of proteins that contain domains related to sea anemone toxins. Evolutionary pressure to maintain a channel-modulatory function may contribute to the conservation of this domain throughout the plant and animal kingdoms.

Tin-based composite anodes for potassium-ion batteries

The electrochemical behaviour of a Sn-based anode in a potassium cell is reported for the first time. The material is active at low potentials vs. K/K(+), and encouraging capacities of around 150 mA h g(-1) are recorded. Experimental evidence shows that Sn is capable of alloying/de-alloying with potassium in a reversible manner.