Intralymphocyte Free Magnesium in a Group of Subjects With Essential Hypertension

Abstract

Despite the importance of magnesium in essential hypertension, few data are available on the ionized intracellular concentration of this ion. We therefore studied intralymphocyte free intracellular magnesium (Mg i ) in 32 untreated essential hypertensive subjects and 27 normotensive control subjects by means of a fluorimetric technique based on the use of the new magnesium-sensitive dye furaptra. We also measured intralymphocyte ionized calcium (Ca i ) with fura 2. No statistically significant differences were found in Mg i in hypertensive compared with normotensive subjects (essential hypertensive, 0.291±0.053 mmol/L; normotensive, 0.293±0.043 [mean±SD]). A statistically significant inverse correlation was established between Mg i and plasma triglycerides in essential hypertensive subjects ( r =−.521, P =.002). The hypertensive group was arbitrarily divided into two subgroups according to plasma triglyceride levels (>2 [n=10] or <2 mmol/L [n=22]), and Mg i proved to be significantly lower in the subgroup with high plasma triglyceride levels compared with either the subgroup with normal triglycerides ( P =.009; 95% confidence interval, 0.013-0.088) or the normotensive control group as a whole ( P =.03; 95% confidence interval, 0.003-0.069) (high-triglyceride hypertensive subgroup, Mg i =0.256±0.045 mmol/L; normal-triglyceride hypertensive subgroup, Mg i =0.307±0.049). No statistically significant differences were found in Ca i in hypertensive compared with normotensive subjects (hypertensive, 53±12 nmol/L; normotensive, 54±14). We did not find statistically significant correlations between Ca i and plasma triglycerides, nor did we find any differences in Ca i between the subgroup of hypertensive subjects with high plasma triglyceride levels and either the subgroup of hypertensive subjects with normal triglycerides or the normotensive control group as a whole. The discrepancies between our results in lymphocytes and data relating to either erythrocytes or platelets emphasize the need for caution before the results are extrapolated from one tissue to the other. The decreased Mg i levels in the subgroup of high-triglyceride hypertensive subjects may suggest a role for magnesium in plurimetabolic syndrome.