Cytosolic Ionized Magnesium Concentration in End-Stage Renal Disease

Abstract

Chronic renal failure is known to raise serum magnesium concentration. However, its effect on intracellular free cytosolic magnesium concentration ([Mg2+]i) has not been clearly delineated. Likewise, whereas hemodialysis (HD) lowers serum magnesium concentration, its effect on [Mg2+]i is unknown. It should be noted that, based on other studies, [Mg2+]i is inversely related to arterial blood pressure in the general population. Given the high prevalence of hypertension in end-stage renal disease (ESRD), the study of [Mg2+]i in this population is of interest. We measured platelet [Mg2+]i in nine ESRD patients, six of whom were hypertensive. Samples were obtained from arterial and venous lines at the start of an HD session, and from the arterial line at the end of an HD session. Five normal volunteers served as controls. [Mg2+]i was measured by spectrofluorometry using Mag-fura-2-AM. Serum magnesium and calcium concentrations were determined by atomic absorption. Compared with the normal control group, the ESRD patients exhibited significantly lower [Mg2+]i but higher serum magnesium concentrations. As expected, HD lowered the serum magnesium concentration. However, platelet [Mg2+]i was unaffected by either a single passage through the dialyzer or the entire dialysis procedure. [Mg2+]i did not correlate with serum magnesium or calcium concentrations, nor with the presence or absence of hypertension.