Abnormal platelet Ca2+ handling accompanied by increased cytosolic free Mg2+ in essential hypertension.
To test the hypothesis that abnormal platelet Ca2+ handling in essential hypertension results from cellular Mg2+ deficiency, cytosolic free Mg2+ concentration ([Mg2+]i) and Ca2+ 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 Ca2+ concentration ([Ca2+]i) and intracellular Ca2+ discharge capacity were higher in hypertensives than in normotensives (22 +/- 5 vs. 18 +/- 5 nM, P < 0.05; 743 +/- 250 vs. 624 +/- 144 nM, P < 0.05, respectively). The thrombin (0. 03-1.0 U/ml)-evoked [Ca2+]i response was also enhanced in platelets from hypertensives in both the absence and presence of extracellular Ca2+. However, basal [Mg2+]i was higher in hypertensives than in normotensives (437 +/- 110 vs. 353 +/- 85 microM, P < 0.05), whereas serum Mg2+ was similar in the two groups. These results oppose the Mg2+ deficiency hypothesis in platelets in essential hypertension.
First Department of Internal Medicine and Department of Clinical Laboratory Medicine, Hiroshima University School of Medicine, Hiroshima 734, Japan.
H
H
Hiraga
T
T
Oshima
M
M
Yoshimura
H
H
Matsuura
G
G
Kajiyama
D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D001794:Blood Pressure; D015992:Body Mass Index; D002118:Calcium / Q000097:blood*; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D003600:Cytosol / Q000378:metabolism; D004573:Electrolytes / Q000097:blood; D002149:Energy Intake; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000503:physiopathology; D008274:Magnesium / Q000097:blood*; D008297:Male; D008875:Middle Aged; D017419:Potassium, Dietary; D012016:Reference Values; D012982:Sodium, Dietary; D013917:Thrombin / Q000494:pharmacology; D014280:Triglycerides / Q000097:blood
D008076:Cholesterol, HDL; D004573:Electrolytes; D017419:Potassium, Dietary; D012982:Sodium, Dietary; D014280:Triglycerides; D002784:Cholesterol; D013917:Thrombin; D008274:Magnesium; D002118:Calcium