Abnormal platelet Ca21 handling accompanied by increased cytosolic free Mg21 in essential hypertension

mal platelet Ca21 handling accompanied by increased cyto-solic free Mg21 in essential hypertension. Am. J. Physiol. 275 (Regulatory Integrative Comp. Physiol. 44): R574–R579, 1998.—To test the hypothesis that abnormal platelet Ca21 handling in essential hypertension results from cellular Mg21 deficiency, cytosolic free Mg21 concentration ([Mg21]i) and Ca21 metabolism were studied in mag-fura 2 and fura 2-loaded platelets from 30 essential hypertensive patients and 30 sex-and age-matched normotensive controls. Basal cytosolic free Ca21 concentration ([Ca21]i) and intracellular Ca21 discharge capacity were higher in hypertensives than in normotensives (22 6 5 vs. 18 6 5 nM, P, 0.05; 743 6 250 vs. 624 6 144 nM, P, 0.05, respectively). The thrombin (0.03–1.0 U/ml)-evoked [Ca21]i response was also enhanced in platelets from hyperten-sives in both the absence and presence of extracellular Ca21