Cytoplasmic free Ca2+ in human platelets: Ca2+ thresholds and Ca‐independent activation for shape‐change and secretion

FEBS Letters

Smith, S.W.¹  Rink, T.J.¹  Tsien, R.Y.¹ 

[1] Physiological Laboratory, University of Cambridge, Cambridge CB2 3EG, England

关键词: Platelet;    Calcium;    Fluorescent indicator;    Shape-change;    Secretion;    Aggregation;   

DOI  :  10.1016/0014-5793(82)81234-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Cytoplasmic free [Ca²⁺], [Ca²⁺]_i, was measured in human platelets using the intracellularly-trapped, fluorescent indicator quin2. Basal [Ca²⁺]_i with the Ca²⁺-ionophore ionomycin revealed apparent thresholds for shape-change, 5-HT release and aggregation of approx. 0.5μM, 0.8μM and 2 μM. Thrombin raised [Ca²⁺]_i to 3 μM fast enough for the Ca²⁺ to have triggered the cell activation. However, thrombin released more 5-HT than ionomycin could, and in Ca²⁺-free medium thrombin evoked shape-change and secretion even when [Ca²⁺]_i remained near basal levels throughout, suggesting the existence of alternative triggers for shape-change and secretory exocytosis.

【 授权许可】

Unknown