Inhibition of platelet aggregation by low concentrations of sodium fluoride. Significance of the intracellular calcium ion concentration.
Sodium fluoride activates platelets but its mechanism of action has not yet been completely identified. We examined the effect of a low concentration of sodium fluoride (which could not cause aggregation) on thrombin-induced changes in the intracellular calcium ion concentration ([Ca2+]i). In the presence of 1 mM extracellular Ca2+, preincubation with a low concentration of sodium fluoride decreased the peak of the thrombin-induced elevation of [Ca2+]i, when measured with aequorin. When [Ca2+] was measured using fura-2, preincubation caused no marked changes in its peak, but the later changes that were thought to mainly reflect extracellular Ca2+ influx were inhibited. The inhibitory mechanism of sodium fluoride appears to depend on reducing extracellular Ca2+ influx. Aequorin appears to reflect [Ca2+]i near the cell membrane and is thus easily affected by the extracellular Ca2+ influx.
Kondo
K
K
First Department of Internal Medicine, Kansai Medical University, Osaka, Japan.
Kitada
C
C
Yoshioka
A
A
Sakane
H
H
Kokawa
T
T
Yasunaga
K
K
D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D003864:Depression, Chemical; D006801:Humans; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D012969:Sodium Fluoride / Q000494:pharmacology*
D010975:Platelet Aggregation Inhibitors; D012969:Sodium Fluoride; D002118:Calcium