Influence of magnesium and potassium deficiency on renal elimination and cardiovascular function demonstrated by impedance cardiography.

In an open controlled trial with 6 male human volunteers Mg and K intake was reduced to 32-35% of normal during a 5- and 4-day period, respectively and 80 mg Furosemide/day was coadministered during the second period in order to induce Mg and K wasting. After each testing period an intravenous infusion of 27.87 mEq Mg and K was administered as K, Mg-D,L-aspartate during 2 h. Electrolyte and fluid balance were analysed before, during and after the testing period. Moreover, impedance cardiographic measurements were carried out in order to determine changes of cardiovascular function, and 24-hour ECGs were recorded simultaneously. It could be shown that reduced Mg and K intake induces depletion of the intracellular stores which was furthermore enhanced by coadministration of the loop diuretic Furosemide. Whereas Mg renal elimination amounted only to 60-54% of intake, K elimination exceeded intake to a considerable extent, a fact that could be explained by the lack of Mg. Changes of cardiovascular function, such as stroke volume, cardiac output and end-diastolic volume, expressed by alterations of total resistivity ZO, were less pronounced, but could be inverted at least partly by a single intravenous infusion of K,Mg-D,L-aspartate. Heart rate and 24-h ECG did not reveal any detectable change. The testing procedure described here can be considered a reliable model for tests in clinical pharmacology.