Evaluation of platelet calcium ion mobilization by the use of various divalent ions.
Divalent ion mobilization in human platelets was evaluated with Fura-2 fluorescence changes induced by Ca2+, Sr2+, Ba2+ and Mn2+. Extracellular Ca2+, Sr2+ and Ba2+ all entered thrombin-stimulated platelets. These divalent ions were also able to refill the intracellular Ca2+ storage sites which had been depleted of Ca2+ by ionomycin treatment, and were released from the storage sites upon thrombin stimulation. However, only the refilling of the storage sites with Ca2+ and Sr2+, but not with Ba2+, were capable of suppressing the opening state of Ca2+ channels assessed with Mn2+ influx. Efflux of intracellularly accumulated divalent ions was observed with Ca2+ and Sr2+ but not with Ba2+. These findings indicate that there are subtle differences in the Ca(2+)-binding domains of the various systems involved in Ca2+ mobilization in platelets, some of which discriminate Ba2+ while accepting Sr2+.
Ozaki
Y
Y
Department of Clinical and Laboratory Medicine, Yamanashi Medical College, Japan.
Yatomi
Y
Y
Kume
S
S
D001464:Barium / Q000378:metabolism*; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D016257:Fura-2 / Q000031:analogs & derivatives; D006801:Humans; D008954:Models, Biological; D013324:Strontium / Q000378:metabolism; D013917:Thrombin / Q000494:pharmacology
C049925:fura-2-am; D001464:Barium; D013917:Thrombin; D002118:Calcium; D016257:Fura-2; D013324:Strontium