Vol. 274, Issue 2, R548-R554, February 1998
Increased cytosolic free Mg2+
and Ca2+ in platelets of
patients with vasospastic angina
Mitsuisa
Yoshimura1,
Tetsuya
Oshima2,
Hiroyuki
Hiraga1,
Yukiko
Nakano2,
Hideo
Matsuura1,
Togo
Yamagata1,
Nobuo
Shiode1,
Masaya
Kato1,
Masayuki
Kambe2, and
Goro
Kajiyama1
1 First Department of Internal
Medicine and 2 Department of
Clinical Laboratory Medicine, Hiroshima University School of Medicine,
Hiroshima 734, Japan
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.
human; aggregation; thrombin
