[Concentration of free intracellular magnesium in the myocardium of spontaneously hypertensive rats treated chronically with calcium antagonist or angiotensin converting enzyme inhibitor].

In this study, we determined a) whether chronic antihypertensive treatment could alter myocardial free intracellular magnesium concentrations, b) whether changes in magnesium concentration would correlate with resistance to anoxia of hypertensive rat hearts. Six-month old male spontaneously hypertensive (HT) rats (n = 11) were compared to rats from the same strain treated with a calcium channel antagonist, nitrendipine (60 mg/kg/j; n = 11) or with a converting-enzyme inhibitor, perindopril (2 mg/kg/j; n = 9) during three months. The hearts were perfused in retrograde isovolumic mode and submitted to a standardized anoxia-recovery protocol. Aortic perfusion pressure and left ventricular pressure were constantly monitored. P-31 NMR spectra were simultaneously recorded and allowed to quantify the changes in myocardial inorganic phosphate, phosphocreatine and ATP. The pH was derived from the chemical shifts of inorganic phosphate and phosphocreatine, and the free intracellular magnesium concentration from the alpha-beta chemical shifts of ATP. Both treatments lowered systolic blood pressure and reversed left ventricular hypertrophy, perindopril being slightly more efficient at the dose administered. Intracellular magnesium concentration, calculated from the P-31 NMR spectra, was 277 +/- 17 microM in the untreated hypertensive group, 311 +/- 15 microM in the nitrendipine group and 401 +/- 17 microM in the perindopril group (p < 0.001 versus untreated and nitrendipine). There was a significant correlation between intracellular magnesium concentration and left ventricular developed pressure at the early stage of post-anoxic recovery (r = 0.61; p < 0.01). P-31 NMR spectroscopy demonstrates an increase in myocardial free intracellular magnesium concentration following chronic administration of an angiotensin-converting enzyme inhibitor, perindopril, spontaneously hypertensive rats.(ABSTRACT TRUNCATED AT 250 WORDS)