Comparison of the effects of supplementation with whey mineral and potassium on arterial tone in experimental hypertension

Whey protein concentrate limits venous thrombosis in rats

To study the influence of whey protein concentrate (WPC-80) on the development of thrombosis, rats were supplemented with 2 doses of WPC-80 (0.3 or 0.5 g/kg) for 7, 14, or 21 days. Then, a 1-h venous thrombosis model was performed in half of the animals. Coagulation parameters, platelet count, and thrombus weight were assessed. Thrombus weight was decreased in rats obtaining WPC-80 and that was significant only for 14- and 21-day supplementation. There were slight differences between groups in coagulation parameters and platelet count but without evident direction. Further research is needed to clarify the observed effects.

Natural sea salt consumption confers protection against hypertension and kidney damage in Dahl salt-sensitive rats

Although sea salts are widely available to consumers nowadays, whether its consumption over refined salt has any real health benefits is largely unknown. This study was conducted to compare hypertension-inducing propensity of natural sea salt (SS) to refined salt (RS) in a well-established animal model of hypertension. Five groups of male Dahl salt-sensitive rats were fed rat chow diet supplemented with various amounts of salt for 15 weeks. The groups were: control (CON, n = 10), 4% RS (RS4), 4% SS (SS4), 8% RS (RS8), 8% SS (SS8) (n = 12 for each group). After 15 weeks, both SS4 and SS8 groups had significantly lower systolic (SBP) and diastolic blood pressure (DBP) compared to RS4 and RS8 rats, respectively. RS8 rats had markedly higher SBP and DBP compared to all other groups. Echocardiography just prior to sacrifice showed abnormalities in RS4, SS8 and RS8 hearts, while CON and SS4 hearts displayed normal measurements. Plasma renin and aldosterone levels of high salt groups were lower than those of CON, and serum electrolytes were similar amongst all groups. Abnormal kidney pathology and high glomerulosclerosis index scores were seen in RS4 and RS8 rats, but SS4 and SS8 kidneys showed relatively normal morphology similar to CON kidneys. Our findings show that consumption of natural sea salt induces less hypertension compared to refined salt in the Dahl salt-sensitive rat.

Interaction between hypertension and cerebral hypoperfusion in the development of cognitive dysfunction and white matter pathology in rats

Hypertension is the most significant modifiable risk factor for vascular cognitive impairment. However, influence of hypertension on the development of ischemic white matter injury and cognitive dysfunction is not fully understood. We compared cognitive functions and neuropathological outcomes of chronic cerebral hypoperfusion induced by bilateral common carotid artery occlusion (BCCAO) between normotensive rats (NRs) and spontaneously hypertensive rats (SHRs). SHRs developed earlier and more severe deficits in spatial memory performance than NRs following BCCAO. Although no significant changes in the gross structure of myelinated white matter or oligodendrocyte number were noted, BCCAO resulted in subtle myelin degeneration and paranodal structural alterations at the nodes of Ranvier, regardless of hypertension. Disruption of the blood-brain barrier (BBB) was predominantly observed in the white matter of SHRs following BCCAO, implying a role of hypertension in BBB dysfunction in chronic cerebral hypoperfusion. In chronic cerebral ischemia, long-standing hypertension may aggravate impairment of BBB integrity, and the leaky BBB may in turn exacerbate dysfunction in the white matter leading to worsening of spatial cognitive performance.

The effects of whey protein on cardiometabolic risk factors

Obesity has reached epidemic proportions worldwide. The health consequences of obesity are more dangerous when associated with the metabolic syndrome and its components. Studies show that whey protein and its bioactive components can promote greater benefits compared to other protein sources such as egg and casein. The aim of this paper is to review the effects of whey protein on cardiometabolic risk factors. Using PubMed as the database, a review was conducted to identify current scientific literature on whey protein and the components of the metabolic syndrome published between 1970 and 2012. Consumption of whey protein seems to play an anti-obesity and muscle-protective role during dieting by increasing thermogenesis and maintaining lean mass. In addition, whey protein has been shown to improve glucose levels and insulin response, promote a reduction in blood pressure and arterial stiffness, and improve lipid profile. The collective view of current scientific literature indicates that the consumption of whey protein may have beneficial effects on some symptoms of the metabolic syndrome as well as a reduction in cardiovascular risk factors.

Potassium Magnesium Supplementation for Four Weeks Improves Small Distal Artery Compliance and Reduces Blood Pressure in Patients with Essential Hypertension

It has been postulated that the loss of arterial compliance may precede cardiovascular diseases, and that arterial compliance is an important parameter to consider when evaluating arterial diseases such as essential hypertension (EH) and the effects of antihypertensive treatment. In all, 133 EH patients and 147 healthy subjects were enrolled in this study. Large arterial compliance (C1) and small arterial compliance (C2) were measured by the CVProfilor DO-2020 CardioVascular Profiling System. Thirty-five patients randomly received magnesium potassium supplementation (magnesium, 70.8 mg/d; potassium, 217.2 mg/d) for four weeks, and 32 patients received lacidipin (4 mg/d) as a control. Before and after the four weeks, blood pressure, C1, and C2 were measured. It was found that arterial compliance was significantly lower in EH patients compared with healthy subjects (C1: 12.53 +/- 0.33 vs. 15.63 +/- 0.30 ml/mmHg x 10, p < 0.01;C2: 3.79 +/- 0.17 vs. 5.69 +/- 0.25 ml/mmHg x 100, p < 0.01). On lacidipine, systolic and diastolic BP decreased 13.27 +/- 1.76 mm Hg and 6.33 +/- 1.55 mm Hg, and C1 and C2 compliance values increased 25.05% +/- 4.49% and 34.50% +/- 7.40%, respectively. On K+ and Mg2+ supplementation, systolic and diastolic BP decreased 7.83 +/- 1.87 mm Hg and 3.67 +/- 1.03 mm Hg, and C1 and C2 compliance values increased 12.44% +/- 4.43% and 45.25% +/- 6.67%, respectively. Decreases in systemic vascular resistance (mean arterial pressure divided by cardiac output) by 11.9% and 16.6 % (p < 0.01) were seen between the drug-induced changes, respectively. Both large arterial compliance and small arterial compliance were decreased in essential hypertension patients. In essential hypertension patients, magnesium and potassium supplementation could improve small arterial compliance, while lacidipine improved large arterial compliance significantly.

Role of potassium in regulating blood flow and blood pressure

Unlike sodium, potassium is vasoactive; for example, when infused into the arterial supply of a vascular bed, blood flow increases. The vasodilation results from hyperpolarization of the vascular smooth muscle cell subsequent to potassium stimulation by the ion of the electrogenic Na+-K+ pump and/or activating the inwardly rectifying Kir channels. In the case of skeletal muscle and brain, the increased flow sustains the augmented metabolic needs of the tissues. Potassium ions are also released by the endothelial cells in response to neurohumoral mediators and physical forces (such as shear stress) and contribute to the endothelium-dependent relaxations, being a component of endothelium-derived hyperpolarization factor-mediated responses. Dietary supplementation of potassium can lower blood pressure in normal and some hypertensive patients. Again, in contrast to NaCl restriction, the response to potassium supplementation is slow to appear, taking approximately 4 wk. Such supplementation reduces the need for antihypertensive medication. "Salt-sensitive" hypertension responds particularly well, perhaps, in part, because supplementation with potassium increases the urinary excretion of sodium chloride. Potassium supplementation may even reduce organ system complications (e.g., stroke).

High-salt diet and responses of the pressurized mesenteric artery of the dog to noradrenaline and acetylcholine

A high-salt diet in rats has been shown to result in enhanced vasoconstrictor and/or reduced vasodilator responses of isolated arteries to agonists. The present experiments were designed to investigate the effects of dietary salt on the responses of the pressurized mesenteric resistance artery of the dog to constrictor and dilator agents. Dogs were fed diets containing three different levels of salt with sodium concentrations (in mmol/kg per day) of 0.4 (low salt; LS), 3.0 (intermediate salt; IS) and 6.0 (high salt; HS) for a period of 4 weeks. At the end of the feeding period, animals were killed and lengths of third-order mesenteric artery were obtained and mounted in a perfusion myograph and changes in internal diameter were measured using a microscope and video-tracking device. The responses to noradrenaline (NA), acetylcholine (ACh) and sodium nitroprusside (SNP) were then determined. The vasoconstrictor responses to NA were identical in the three groups. However, the relaxation response of the vessels to ACh was attenuated in HS dogs compared with LS dogs (P < 0.05), but not with IS dogs. The application of N(G)-nitro-l-arginine methyl ester, an inhibitor of nitric oxide synthase, reduced the relaxation responses to ACh comparably in all three groups. The relaxation responses of the vessels to SNP were similar in all groups. These results indicate that, in the dog mesenteric resistance artery, a high-salt diet does not affect vasoconstrictor responses to NA, but does attenuate the vasorelaxant action of ACh, largely by inhibiting the production of endothelium-derived relaxing factor.

High salt diet modulates cAMP- and nitric oxide-mediated relaxation responses to isoproterenol in the rat aorta

This study tested the hypothesis that nitric oxide (NO) production contributes to relaxation induced by 3',5'-cyclic adenylate monophosphate (cAMP)-elevating agents and that high salt diet impairs this mechanism of relaxation. Relaxation response to isoproterenol but not sodium nitroprusside, a NO donor, was reduced in the thoracic aorta from rats that were placed on a high salt diet (8% NaCl; 60+/-4%, P<0.001). 1H-[1,2,4]oxadiazolol [4,3,-alpha]quinoxalin-1-one (ODQ, 10 microM), a soluble guanylate cyclase inhibitor, but not N(omega)-nitro-L-arginine methyl ester (L-NAME, 100 microM), an inhibitor of NO synthase (NOS), attenuated the relaxation to isoproterenol (59+/-16%, P<0.01). High salt diet also impaired the relaxation responses to forskolin, an activator of adenylate cyclase, or 8-Bromo-cAMP (8-Br-cAMP). (N-[2-((p-bromocinnamyl)aminoethyl]-5-isoquinolinesulfonamide hydrochloride (H-89) (8 microM), an inhibitor of cAMP-dependent protein kinase, did not affect the relaxation produced by isoproterenol. These data suggest that high salt diet impairs relaxation response to isoproterenol by a dual mechanism involving diminished NO/NOS pathway linked to cGMP pathway and diminished cAMP pathway that is independent of protein kinase A.

The effect of nutrient profiles of the Dietary Approaches to Stop Hypertension (DASH) diets on blood pressure and bone metabolism and composition in normotensive and hypertensive rats

Hypertension has been associated with abnormalities of Ca and bone metabolism. Consequently, dietary strategies aimed at reducing blood pressure may also benefit bone health; however, this issue has received little attention. Therefore, the objective of the present study was to investigate the effect of two antihypertensive-type diets on blood pressure and bone metabolism and composition in normotensive (Wistar-Kyoto NHsd, WKY) and hypertensive (spontaneously hypertensive NHsd, SHR) rats. Thirty WKY and thirty SHR male rats, 14 weeks old, were separately randomized by weight into three groups of ten rats each. One group from each strain was given a control diet while the other two groups were fed two anti-hypertensive (high fruit and vegetable (F/V) and high fruit and vegetable and low-fat dairy produce (combination)) diets for 8 weeks. SHR rats were significantly (P<0.01) heavier than WKY rats. Blood pressure and femoral length, width, dry weight, ash, Ca, Mg, P and bone mineral mass were significantly (P<0.0001) greater in SHR than WKY rats, but were unaffected by diet, irrespective of strain. While markers of bone formation (serum osteocalcin) and bone resorption (urinary pyridinoline and deoxypyridinoline) were similar in both strains, these markers were significantly (P<0.05) lower (28-31, 16-23, 31-33 % respectively) in the SHR rats fed the combination diet relative to those fed the control and F/V diets. Bone turnover in WKY rats was unaffected by diet. In conclusion, these findings suggest that the combination diet may benefit bone metabolism in hypertensive animals. However, as blood pressure was unaffected by this diet, the mechanism by which it reduced bone turnover requires further investigation.

Change in endothelial function in mesenteric arteries of Sprague-Dawley rats fed a high salt diet

A high salt diet in some species results in elevated arterial blood pressure and alterations in vascular smooth muscle responses to agonists. Weanling male Sprague-Dawley rats were given either a high salt diet containing 8 % or a low salt diet of 0.4 % sodium chloride for a period of 4 weeks. At the end of the feeding period, tail systolic pressure was higher in the high salt than in low salt rats. The rats were then killed and the intestines removed. Vascular smooth muscle (VSM) responses were estimated from the changes in lumenal diameter of pressurised second order mesenteric resistance arteries. High salt diet resulted in enhanced VSM responses to noradrenaline. The vessels dilated in response both to acetylcholine and to sodium nitroprusside and the responses were similar in vessels from both high and low salt rats. However, vessels from high salt rats were resistant to the blocking of endothelium derived nitric oxide (EDNO) with L-NAME and the responses were instead abolished by blocking endothelium derived hyperpolarising factor (EDHF) with apamin and charybdotoxin. These results show that in Sprague-Dawley rats, a high salt diet enhances the vasoconstriction in response to noradrenaline. The vasodilatory responses to acetylcholine were not significantly changed. However, they appeared to be mediated mainly by EDHF rather than by EDNO as in the low salt animals.

Potassium channel function in vascular disease

Potassium ion (K(+)) channel activity is a major regulator of vascular muscle cell membrane potential (E(m)) and is therefore an important determinant of vascular tone. There is growing evidence that the function of several types of vascular K(+) channels is altered during major cardiovascular diseases, such as chronic hypertension, diabetes, and atherosclerosis. Vasoconstriction and the compromised ability of an artery to dilate are likely consequences of defective K(+) channel function in blood vessels during these disease states. In some instances, increased K(+) channel function may help to compensate for increased vascular tone. Endothelial cell dysfunction is commonly associated with cardiovascular disease, and altered activity of nitric oxide, prostacyclin, and endothelium-derived hyperpolarizing factor could also contribute to changes in resting K(+) channel activity, E(m), and K(+) channel-mediated vasodilatation. Our current knowledge of the effects of disease on vascular K(+) channel function almost exclusively relies on interpretation of data obtained by using pharmacological modulators of K(+) channels. As further progress is made in the development of more selective drugs and through molecular approaches such as gene targeting technology in mice, specific K(+) channel abnormalities and their causes in particular diseases should be more readily identified, providing novel directions for vascular therapy.

Blood pressure responses to high-calcium skim milk and potassium-enriched high-calcium skim milk

OBJECTIVE

This study was designed to evaluate the effect of high-calcium skim milk or potassium-enriched high-calcium skim milk on blood pressure compared with nonenriched skim milk.

DESIGN

This was a randomized double-blind controlled trial. Each milk intervention lasted for 4 weeks, with a minimum of 4 weeks of wash-out between interventions.

METHODS

We recruited 38 healthy people, aged over 40 years, to take part in a double-blind, randomized, controlled cross-over study. We asked them to replace their usual liquid milk with two servings per day of skim milk (control), high-calcium skim milk or potassium-enriched high-calcium skim milk. We measured office blood pressures (seated and standing) at the start and after 2 and 4 weeks of milk intervention and we measured daytime ambulatory blood pressures at the start and after 4 weeks of milk intervention. Each milk intervention was interspaced by a 4-week interval.

RESULTS

Office systolic blood pressure (standing) decreased from 127 +/- 16 to 124 +/- 16 mmHg (P<0.05) after 4 weeks of skim milk and from 130 +/- 18 to 126 +/- 17 mmHg (P<0.05) after 4 weeks of high calcium skim milk. After 4 weeks of consuming the potassium-enriched high-calcium milk, systolic blood pressure decreased from 125 +/- 18 to 117 +/- 16 mmHg (P<0.001) seated, and from 130 +/- 16 to 122 +/- 15 mmHg (P<0.001) standing. There were no significant changes in office diastolic blood pressure after any milk. There was no change in ambulatory blood pressure after either skim milk or high-calcium skim milk. After 4 weeks of potassium-enriched high-calcium milk, ambulatory daytime systolic blood pressure decreased from 138 +/- 13 to 135 +/- 11 mm Hg (P<0.05) and daytime diastolic blood pressure decreased from 80 +/- 8 to 78 +/- 9 mmHg (P<0.05).

CONCLUSIONS

High-calcium milk enriched with potassium has a small hypotensive effect in healthy people aged over 40 years.