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Magnesium and potassium in the prevention of stroke

Correction of the pathologic conditions that increase the risk of stroke plays an important role in the prevention of stroke. Furthermore, regulation of magnesium and potassium exchange is a vital aspect of resolving this problem.

Potassium

Potassium is a main intracellular cation. The content of this substance in the plasma under normal conditions is 3.5-5 mmol / L, and within the cells - 150 mmol / L. Thus, the extracellular fluid contains less than 2% of the total amount of potassium in the body. This ratio is maintained by the action of Na +, K + -ATP, which actively transfers sodium ions from the cell and potassium ions into it. Thus, a transmembrane resting potential is created, which is extremely important for the normal functioning of muscle and nerve tissue.

In view of the fact that the loss of potassium from the extracellular fluid (with the abuse of diuretics and laxatives, with diarrhea and because of acidosis) is quickly compensated for by the influx of this substance from the cells, the concentration of this ion in the extracellular space varies very little for a long time. This leads to the fact that critical potassium deficiency, fraught with the occurrence of cardiovascular disorders, often remains unnoticed in the conduct of a standard study.

Hypokalaemia (Kaliopenia, Hypopotassemia)

The distribution of potassium in the body is affected by ABB (acid-base balance), hormones, osmolality and the rate of cell renewal. Insulin indirectly increases the activity of Na +, K + -ATP, which facilitates the transfer of potassium to liver cells and muscle cells. Patients suffering from diabetes mellitus are at an increased risk for developing hypokalaemia. The main reasons for this are:

Insufficient amount of potassium intake with the food;
Hyperglycemia;
Intensive fluid loss (diarrhea, laxatives, sweating, etc.);
Hypomagnesemia;
Hyperaldosteronism.

Hypokalaemia is diagnosed in case potassium level in serosity is less than 3.6 mmol/L. Hypokalaemia manifestations include:

General muscle weakness;
Cardiac arrhythmias;
Paralytic ileus.

Among typical electrocardiographic changes there are inverted or flat T-waves, visible U-teeth and ST-segment depression.

Data from various clinical and epidemiological studies have confirmed the important role of potassium deficiency in the pathogenesis of arterial hypertension. An increase in potassium intake leads to an antihypertensive effect due to increased sodium natriuresis, direct vasodilation, enhanced baroreflex sensitivity and a decrease in cardiovascular reactivity to angiotensin II or norepinephrine.

Connection with blood pressure

Outsanding international studies have shown that there is an inverse relationship between potassium intake from food and blood pressure. A meta-analysis of random controlled trials was conducted and the effect of sodium intake on blood pressure was studied. This analysis included 33 clinical studies, among which the only difference was the intake of potassium by patients. The dosage of potassium (mainly in the form of potassium chloride) ranged from 60 to more than 100 mmol / day. The results of the study showed that potassium intake was associated with a significant decrease in mean diastolic and systolic blood pressure (-4.4 and -2.4 mmHg, respectively).

The maximum effect was observed in the group of patients with the highest competitive sodium intake. Based on the results of this analysis, it can be assumed that a reduced intake of potassium can have almost decisive importance in the development of high blood pressure. Therefore, the authors recommended increasing potassium consumption by patients for the treatment and prevention of hypertension and cardiovascular diseases.

Stroke prevention

Potassium correction also plays an important role in the prevention of strokes due to the possibility of arrhythmias, which, in turn, can cause cardioembolism. Moderate hypokalaemia may increase the likelihood of arrhythmias in patients with left ventricular hypertrophy, heart failure, or IHD (CAD).

Concentration of potassium ions has a maximum effect on the heart work of all the components relating to extracellular fluid. The ratio between intra- and extracellular potassium levels is the primary determining factor for the residual membrane potential. Dynamics of potassium levels has an effect on the electrophysiological properties of the membrane and can affect the generation of the pulse with carrying it through the heart. Decrease in ion concentration causes an increase in pacemaker activity and activation of heterotopic foci of excitation - this may be accompanied by cardiac rhythm disturbances.

Potassium deficiency, as well as potassium channel blockade represents an increased chance of a long-term repolarization (a pathogenetic factor of flicker and flutter development). The effect that hypokalemia has on repolarization increases if a person suffers many pathologies including myocardial infarction, congestive heart failure and left ventricular hypertrophy.

Despite the data given by different authors, the relationship between the incidence of arrhythmias and hypokalaemia is not reliable. A study was conducted where authors examined 17 men with hypertension. The goal was to identify the relationship of hypokalaemia due to diuretic use with ventricular ectopic activity. During the study, they found that the risk of ventricular ectopic activity occurred in a group of patients who belonged to the older age group and had signs of organic heart damage.

The severity and frequency of ventricular ectopic activity in such patients increased with diuretic therapy. Recovery of potassium levels with the help of food additives or potassium-sparing agents reduced the frequency and severity of arrhythmias in these patients by 85%, even after stopping the intake of diuretics.

Based on this, the authors recommended conducting laboratory and clinical observation to identify patients with high ventricular ectopic activity like elderly people with organic heart disease. They might need to recover potassium levels in the serosity. Also, the authors suggested that the detection of electrocardiographic abnormalities in patients with impaired potassium metabolism is not a factor that influences the occurrence of arrhythmia. There may probably be deviations in the heart rhythm with a combination of low potassium and heart disease.

Despite the fact that the relationship between hypokalaemia and complicated ventricular arrhythmia remains very doubtful, there is information that hypokalaemia can lead to the onset of ventricular fibrillation or a persistent ventricular tachycardia (especially in patients with acute myocardial infarction). However, the exact mechanism that results in hypokalaemia leading to ventricular fibrillation or sudden cardiac death in the absence of a heart attack has not yet been identified.

In patients receiving anti-arrhythmic drugs with severe arrhythmias in a history of hypokalaemia can completely eliminate the effect of using these medications and increase the risk of recurrence of arrhythmia. Consequently, an important task is to define a more stringent standard indicating the purpose of treatment for patients with risk of severe ventricular tachyarrhythmias and heart disease.

Data from epidemiological studies and animal experiments show that high levels of potassium can help reduce the risk of stroke. Despite the fact that part of the protective effect of potassium may be a consequence of lowering blood pressure, an analysis of the animal experiments shows that there may be other protective mechanisms, including reduction of arterial thrombosis, proliferation of smooth muscle vessels and the formation of free radicals. Also, experiments have shown that potassium can help reduce macrophage adhesion to the vascular wall, which reduces the risk of atherosclerosis.

In 1987, the results of a prospective study, lasting 12 years, showed that the relative risk of mortality associated with stroke was significantly lower with increased potassium intake. Multivariate analysis showed that daily production of an additional 10 mmol of potassium provided a reduction in the relative risk of mortality in stroke by 40%.

Comparable results were obtained in a study conducted in 1998. Also, researchers found that the use of additives based on potassium is inversely associated with the risk of stroke - especially in men with hypertension. The authors suggested that this situation may be associated with a decrease in the risk of hypokalaemia. In this regard, the authors recommend increasing the intake of potassium by replacing processed foods with fruits, juices and vegetables. They also suggested using potassium supplements to treat patients with hypertension.

Magnesium

Magnesium is a vital element which is contained in all tissues of the body in a requisite amount. Magnesium is necessary to preserve the normal function of cells. The element takes part in more than 300 enzyme reactions (including the synthesis of nucleic acids and proteins, as well as energy metabolism). In particular, magnesium is involved in the regulation of nerve impulses transmission and muscle contraction, reduces the heart rate and reduces the need for myocardium in oxygen. Magnesium has an anti-ischemic effect on myocardial tissue. Reduced contractivity of arterioles smooth muscles myocytes leads to vasodilatation, including coronary vessels, and also to an increase in coronary blood flow.

The body gets magnesium along with the food. Magnesium deficiency in the body can occur if eating habits (diets) are disturbed or when there is an increased demand for magnesium (heavy physical / mental stress, pregnancy, stress or diuretic use). Magnesium is an important cofactor potassium entering the body and maintaining its level inside the cells. A recent study of cell models confirmed that magnesium has a critical role in maintaining the level of potassium within cells, and also proved that these mechanisms are multifactor in nature.

It was proved that the joint deficiency of magnesium and potassium can cause insufficient saturation of potassium. It is recommended to use combined medications of potassium and magnesium to treat patients with hypokalaemia. Food sources of magnesium include peas, beans, whole grain cereals, nuts, seafood, cocoa and dark green vegetables.

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