Thromb Haemost 1987; 57(01): 001-010
DOI: 10.1055/s-0038-1651051
Original Articles
Schattauer GmbH Stuttgart

Abnormal Aggregation Accompanies Abnormal Platelet Ca2+ Handling in Arterial Thrombosis

Authors

  • Nabila M Shanbaky

    The Department of Medicine Medical School of the University of Miami, Miami, FL, USA
  • Yeon Ahn

    *   The Department of Pharmacology and the Center for Blood Diseases, Miami, FL, USA
  • Wenche Jy

    The Department of Medicine Medical School of the University of Miami, Miami, FL, USA
  • William Harrington

    *   The Department of Pharmacology and the Center for Blood Diseases, Miami, FL, USA
  • Luis Fernandez

    *   The Department of Pharmacology and the Center for Blood Diseases, Miami, FL, USA
  • Duncan H Haynes

    The Department of Medicine Medical School of the University of Miami, Miami, FL, USA
Further Information

Publication History

Received 01 April 1986

Accepted after revision 29 September 1986

Publication Date:
06 July 2018 (online)

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Summary

The resting levels of cytoplasmic Ca2+ (measured by Quin 2 fluorescence) and dense tubular Ca2+ (measured by chlorotetracycline, CTC, fluorescence) are shown to be higher in platelets from patients with arterial thrombosis than from normal donors. Turbidmetric studies of aggregation of diluted platelet-rich plasma (PRP) at 135 μM Ca2+ showed increased rates of aggregation for patients relative to normal controls. For ADP-stimulated aggregation, increased maximal rates (Vmax) and decreased doses for half-maximal rates were observed. With collagen-stimulated aggregation, patient samples showed only decreased ED50 values relative to normal controls. The changes in these values are linearly correlated with the elevation of resting dense tubular Ca2+ level determined by the calcium-CTC test carried out at 2 mM external Ca2+. For ADP-stimulated aggregation this relationship can be mimicked by pre-incubating normal platelets with subcritical concentrations of the Ca2+ ionophore A23187.

These results suggest that elevated cytoplasmic and dense tubular Ca2+ in the “resting state” is a major factor in arterial thrombosis, rendering the platelet more sensitive to the stimulation by physiologic agents.