Increased cytosolic free Mg2+ and Ca2+ in platelets of patients with vasospastic angina
Yoshimura, M.; Oshima, T.; Hiraga, H.; Nakano, Y.; Matsuura, H.; Yamagata, T.; Shiode, N.; Kato, M.; Kambe, M.; Kajiyama, G.
American Journal of Physiology 274(2): R548-R554
1998
ISSN/ISBN: 0002-9513 PMID: 9486316 Document Number: 493162
This study was designed to test the hypothesis that the cellular metabolism of Ca2+ and Mg2+, which is important in platelet function, is abnormal in the platelets of patients with vasospastic angina. Cytosolic free Mg2+ concentration ((Mg2+)i) and Ca2+ handling were determined in the platelets of 24 patients with vasospastic angina and 24 control subjects by use of mag-fura 2 and fura 2. Platelet aggregation was also examined. Basal (Mg2+)i and cytosolic free Ca2+ concentration ((Ca2+)i) in platelets were significantly higher in patients with vasospastic angina than in control subjects. The amplitude of the (Ca2+)i transient induced by thrombin (0.03-1.0 U/ml) was significantly increased in the presence, but not in the absence, of extracellular Ca2+ in patients with vasospastic angina, as compared with controls. Therefore, the influx of Ca2+ across the plasma membrane may be accelerated in vasospastic angina. Thrombin (0.1-1.0 U/ml)-induced maximum aggregation response was significantly greater in patients with vasospastic angina than in controls. Results suggest that increased (Mg2+)i and altered Ca2+ handling by platelets may be associated with coronary vasospasm.