INTRALYMPHOCYTE FREE MAGNESIUM AND CALCIUM AND INSULIN TOLERANCE-TESTIN A GROUP OF ESSENTIAL HYPERTENSIVE PATIENTS

In order to assess the links which are claimed to exist between periph eral insulin resistance and intracellular magnesium and calcium concen trations, we measured free intralymphocyte magnesium (Mg-i) and calciu m (Ca-i) concentrations as well as the rate constant of plasma glucose disappearance (K-itt) after insulin injection (insulin tolerance test : ITT) in a group of 16 normotensive control subjects (NC) and 34 esse ntial hypertensive subjects (EH). Mg-i and Ca-i were measured in tripl icate by means of a fluorimetric technique based-on the dyes furaptra and fura-2 respectively. K-itt values proved significantly reduced in EH as compared to NC (M +/- SD, EH: 4.49 +/- 1.31 vs 5.28 +/- 1.19, P <0.05; 95% confidence limits: 0.23-1.5). Mg-i and Ca-i were not statis tically different in EH as compared to NC subjects (Mg-i, NC: 266 +/- 20 mu mol/l; EH : 245 +/- 50 mu mol/l; Ca-i, NC: 47 +/- 9 nmol/l, EH: 46 +/- 13 nmol/l). We found a statistically significant inverse correl ation in the whole study group between K-itt and body mass index (R= - 0.363, P<0.01) and a statistically significant positive correlation be tween K-itt and Mg-i (R= 0.347, P=0.013) was found. In a step-up multi variate regression analysis including blood pressure, plasma lipids, B MI, plasma magnesium, fasting insulin, fasting glucose, Mg-i and Ca-i, the dependent variable K-itt is statistically significantly correlate d with body mass index and Mg-i. In a first attempt to study the relat ionships between insulin resistance, Mg-i and Ca-i in nucleated cells, the chosen index of peripheral resistance seems to be linked to intra cellular free magnesium.