Search

The aim of this study was to evaluate if a nutritional dose of magnesium given orally changes the blood pressure in untreated hypertensive patients and if orally-given magnesium had any influence on serum and muscle magnesium and potassium. A randomized, double-blind crossover study design was followed with magnesium 15 mmol/day or placebo treatment for two months. Thirty-nine patients aged 20-59 years, were treated. Samples for magnesium and potassium in blood, muscle and urine were taken at entry time, after two months (crossover time) and after four months (end of study). Systolic and diastolic supine and standing blood pressures were measured at the same times. No significant change in blood pressure, serum or muscle concentrations of electrolytes were observed on magnesium treatment. Urine magnesium rose significantly on magnesium, and it decreased significantly on placebo. Therefore results suggest that 15 mmol magnesium/day, given to untreated mild-to-moderate hypertensives does not alter blood pressure nor the concentrations of magnesium and potassium in serum and muscle, in patients with normal magnesium turnover.

Seventy patients on long-term diuretic therapy for arterial hypertension and/or congestive heart failure were investigated with regard to skeletal muscle electrolytes and the results of a peroral glucose tolerance test. A significant correlation was observed between the muscle content of potassium and the ability to handle a glucose load. Thirty patients underwent a second set of samples six months after the first one, 23 of whom had a reduction of their muscle potassium content relative to the first biopsy. They simultaneously demonstrated a significant impairment of glucose tolerance.

The effects on plasma and skeletal muscle electrolytes of the combination of triamterene 37.5 mg and hydrochlorothiazide 25 mg daily were studied in 19 patients on prior long-term (greater than 1 year) diuretic therapy for arterial hypertension and/or congestive heart failure. A further 20 patients fulfilling the same admission criteria were used as controls. Blood samples and skeletal muscle biopsies were taken before the study and after 6 months on therapy. The diuretic-treated group had a significant increase in skeletal muscle potassium and magnesium after 6 months on therapy as compared to the controls. Thus, the combination of triamterene and hydrochlorothiazide appeared effective in preserving the cellular content of potassium and magnesium on a long-term basis in the type of patient studied.

Thirty-four patients suspected of being magnesium deficient were given intravenous infusions of potassium and magnesium. The muscle contents of sodium, potassium, magnesium, and chloride were determined by atomic absorption spectrophotometry on skeletal muscle samples obtained by percutaneous biopsies. The frequency of ventricular etopic beats (VEBs) was assessed from a 3-hour ECG tape recording before the infusions and after the completion of each infusion. The potassium infusions did not result in any changes in the cellular potassium content, nor in the frequency of VEBs. After the magnesium infusions, however, a significant increase was noted in the cellular potassium content and likewise a significant decrease in the frequency of VEBs. This emphasizes the importance of magnesium in potassium metabolism.

To evaluate a possible relationship between Mg deficiency and the development of microvascular disease in diabetes mellitus, quadriceps muscle biopsies for estimating Mg content and capillary basement membrane thickness, were studied in 16 patients with type I diabetes. The diabetic individuals had a slightly but significantly reduced muscle Mg content as compared with 13 healthy controls. There was a significant, positive correlation between capillary basement membrane width and age in the diabetic group, but no relationship between membrane thickness and muscle or serum concentration of Mg. However, diabetic patients with retinopathy (n = 6) showed a nonsignificant inverse correlation between basement membrane thickness and Mg parameters. The opposite tendency was found in patients without retinal lesions.

Following a lymphocyte separation technique, the lymphocyte content of magnesium and potassium was determined by atomic absorption spectroscopy in 28 subjects. Simultaneously, skeletal muscle biopsies were obtained by a percutaneous technique and analyzed for magnesium and potassium. In this study there was not significant correlation between the lymphocyte and the skeletal muscle content of magnesium or potassium, except in the group of three normal volunteers and nine patients with mild arterial hypertension.

To study the effect of a combination of amiloride, 5 mg, and hydrochlorothiazide, 50 mg (Moduretic), on plasma and skeletal muscle electrolytes in patients on long-term diuretic therapy (greater than 1 year) for arterial hypertension and/or congestive heart failure, 58 patients were recruited. Fifty-five patients completed the study, 27 controls and 28 in the treatment group. The Moduretic group demonstrated a significant increase in skeletal muscle potassium and magnesium values and a significant decrease in systolic blood pressure after 6 months on therapy. There was no significant change in these parameters in the control group. It is concluded that this combination of amiloride and hydrochlorothiazide is capable of preserving the internal and external balance of potassium and magnesium on a long-term basis in the patient categories studied.

The effect of adding spironolactone (Aldactone) on muscle electrolytes was studied in 48 patients with arterial hypertension and/or congestive heart failure who had received conventional diuretic treatment, including a potassium supplement, for more than 1 year. After 6 months on spironolactone 100 mg/day as well as the original conventional diuretic therapy, there was a significant increase in both skeletal muscle potassium and magnesium. At the same time these parameters decreased in the control group. In the spironolactone group there was also a significant increase in the mean serum potassium and creatinine levels. There was a significant fall in blood pressure in the spironolactone-treated group.

Serum and muscle electrolytes were determined in a case of primary aldosteronism before and after potassium and magnesium infusions as well as spironolactone treatment and following surgery. Repeated potassium infusions resulted in a transient normalization of the muscle potassium (K/m), followed within 3-4 days by a return to the previously low K/m. Magnesium infusions did not give any increase in muscle magnesium (Mg/m). On the contrary, there was a decrease in Mg/m concomitant with a decrease in K/m. Treatment with spironolactone for one month was followed by a normalization of both serum and muscle electrolytes. Following surgery the serum potassium and K/m remained normal, but the serum magnesium (Mg/s) and Mg/m showed a decrease to subnormal values. Despite the initial findings of normal Mg/s and Mg/m as well as excretion of more than 80% of the i.v. magnesium dose, this may indicate that there was a magnesium deficiency in the skeletal pool.

Investigations regarding plasma and skeletal muscle electrolytes were carried out in 537 patients on long-term diuretic treatment (greater than 1 year) for arterial hypertension (n = 240) and/or congestive heart failure (n = 297). In both groups there were significant decreases in both plasma and skeletal muscle K and Mg, while the muscle Na values as well as the total and extracellular water content of skeletal muscle were increased.

Plasma and skeletal muscle electrolytes were measured in 13 patients with Crohn's disease, and in an age- and sex-matched reference group. Patients with Crohn's disease demonstrated significantly lower muscle potassium content (p less than 0.01) than did controls. Patients with extensive involvement of the bowel tended to have lower muscle potassium content. The patient population did not differ significantly from the controls with regard to skeletal muscle magnesium content but displayed a far wider range of values. Our results indicate that potassium depletion is present in nonresected patients with Crohn's disease.

Twenty patients on long-term diuretic therapy for arterial hypertension and/or congestive heart failure were given a supplementary dose of 15 mmol magnesium aspartate hydrochloride per day for 6 months. Nineteen patients, fulfilling the same admission criteria as the treatment group, served as controls. The addition of magnesium aspartate hydrochloride resulted in a significant rise of the cellular potassium and magnesium content and in a significant decrease of both systolic and diastolic blood pressure. It is concluded that supplementation with magnesium aspartate hydrochloride may effectively prevent the diuretic induced disturbances of electrolyte balance.

Samples from cardiac and skeletal muscle were obtained immediately after death in a case of fatal digitalis intoxication. Intra- and extracellular electrolytes were determined by atomic absorption spectrophotometry. No changes were found in the extracellular electrolytes, and only modest changes were noted in skeletal muscle. In cardiac muscle, however, profound electrolyte disturbances were recorded with an inward shift of sodium and an outward shift fo potassium. This signifies an extensive and early inhibition of the membrane ATPase in cardiac muscle and stresses the importance of immediate and vigorous treatment of the intracellular electrolyte disturbances with a view to suppressing serious and potentially lethal arrhythmias.