Lack of deficiency in extracellular and intralymphocyte free Mg2+ in genetically hypertensive rats

Recently it has been suggested that Mg deficiency may play a key role in hypertension and several cardiovascular diseases. In order to investigate the status of Mg in genetic hypertension, the cytosolic free Mg2+ concentration (Mg2+]i) in the lymphocytes and serum concentrations of free Mg2+ and total Mg were measured in spontaneously hypertensive rats/Izumo (SHR/Izm), stroke-prone spontaneously hypertensive rats/Izumo (SHRSP/Izm), and Wistar-Kyoto rats/Izumo (WKY/Izm). In addition, the basal cytosolic free Ca2+ concentration (Ca2+]i) was assessed in the three strains. Systolic blood pressure was highest in SHRSP/Izm and lowest in WKY/Izm. No significant differences were found in either the serum free Mg2+ concentrations or the serum total Mg concentrations among WKY/Izm, SHR/Izm, and SHRSP/Izm. Mg2+]i in the lymphocytes was significantly higher in SHR/Izm than in WKY/Izm (254 +/- 51 versus 201 +/- 36 mumol/liter, p < 0.05), but the Mg2+]i in SHRSP/Izm (211 +/- 34 mumol/liter) was at the same level as in WKY/Izm. No significant correlation was found between Mg2+]i in the lymphocytes and systolic blood pressure. Basal Ca2+]i did not differ among the three strains. Thus, an increase in Ca2+]i is not obligatory in all cells of genetically hypertensive rats. Mg deficiency may not exist in the intracellular or extracellular space in genetically hypertensive rats.