Diuretics and intracellular cations.

Abstract

155 patients with acute myocardial infarction were followed up for 6 months in a controlled, prospective, randomised study to determine the effects of diuretic therapy on the extraand intracellular concentrations of potassium, magnesium and calcium. Methods: A slight modification of a technique (Ryan et al. 1979, 1981) used to measure lymphocyte and erythrocyte concentrations of potassium, magnesium and calcium was performed (Abraham et al. 1985), enabling measurements of potassium, magnesium and calcium in both lymphocytes and erythrocytes to be made in less than IOmlofblood. Patients with acute myocardial infarction were randomised into 2 comparable groups (110 in group A, 105 group B) immediately upon admission to the hospital. Patients from these 2 groups who did not require diuretic therapy formed a third group. However, once started on a diuretic, the patients were kept on the same treatment for the 6 months of follow-up after discharge from hospital. Of the original 215 patients entered into the study, 155 remained eligible for evaluation. Of these, 70 patients who did not receive any diuretics formed the central group; 48 patients (group A) received frusemide and potassium chloride, and 37 received hydrochlorothiazide (50mg) plus amiloride (5mg; group B). The dose of frusemide was 40 to 120 (mean 40) mg/day with 2 tablets of potassium chloride (1200mg) for each 40mg offrusemide. Patients in group B received I tablet of hydrochlorothiazide plus amiloride daily. Patients were seen at I, 2, 4 and 6 months after discharge. Results: After 6 months of treatment, there were no differences between groups with regard to serum sodium, chloride, blood urea nitrogen, creatinine or uric acid concentrations. Serum potassium, magnesium and s;alcium concentrations were also the same in all groups. However, lymphocyte potassium, magnesium and calcium concentrations were all significantly reduced in the frusemide group (p < 0.03) when compared with either the controls or the patients receiving hydrochlorothiazide plus amiloride. Erythrocyte potassium, magnesium and calcium concentrations were also significantly reduced (p < 0.01) in the frusemide group compared with the control group.