Change in intracellular calcium ions during shear induced platelet aggregation

K. Kawakami, M. Fukuyama, K. Sakai, I. Itagaki, K. Kawano, M. Handa, Y. Ikeda

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Abstract

The authors have developed a method to measure intracellular calcium ion concentration ([Ca2+]i) during shear-induced platelet aggregation. A cone and plate viscometer was adapted for continuous recording of both light transmission and fluorescence intensity. Citrated platelet rich plasma was incubated with Indo-1AM at a concentration of 10 μm for 30 min at 37° C, then applied to the albumin density gradient to prepare washed platelets. To Indo-1AM loaded washed platelets, fibrinogen, and von Willebrand factor (vWf) were added, with 1 mM CaCl2. Platelets were then exposed to changing shear stress (6-108 dynes/cm2) for simultaneous measurement of aggregation and [Ca2+]i. [Ca2+]i in resting platelets was estimated as approximately 100 nM. At low shear stress (10-20 dynes/cm2), [Ca2+]i did not change. In contrast, a marked increase in [Ca2+]i was observed concurrent with aggregation at high shear stress (100-108 dynes/cm2). However, no increase was seen in the presence of 1 mM EGTA. The increase was prevented by monoclonal antibodies against GPIb or vWf, which inhibited vWf binding to GPIb. A monoclonal anti-vWf antibody, which inhibited vWf binding to the GPIIb/IIIa complex, did not affect [Ca2+]i increase during high shear induced platelet aggregation. These results suggest that binding of vWf to GPIb may trigger Ca2+ influx.

Original languageEnglish
Pages (from-to)M696-M699
JournalASAIO Transactions
Volume36
Issue number3
Publication statusPublished - 1990 Jul 1

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ASJC Scopus subject areas

  • Biophysics

Cite this

Kawakami, K., Fukuyama, M., Sakai, K., Itagaki, I., Kawano, K., Handa, M., & Ikeda, Y. (1990). Change in intracellular calcium ions during shear induced platelet aggregation. ASAIO Transactions, 36(3), M696-M699.