Ardlie N G, Bell L K, McGuiness J A
Thromb Res. 1987 May 15;46(4):519-26. doi: 10.1016/0049-3848(87)90153-8.
Changes in cytoplasmic free calcium in response to epinephrine in combination with other agonists were studied in human platelets loaded with the fluorescent calcium indicator, quin 2. In the presence of 1mM external calcium, epinephrine augmented the increase in cytoplasmic free calcium in response to collagen or thrombin, and this was inhibited by yohimbine. In the absence of extracellular calcium, thrombin and collagen only caused a small increase in cytoplasmic free calcium, and the response was not enhanced by epinephrine. High concentrations of epinephrine alone caused a small increase in cytoplasmic free calcium in platelets when calcium was present externally. Inhibition of cyclooxygenase by aspirin markedly reduced the calcium response to collagen and almost completely inhibited potentiation by epinephrine. The calcium response to thrombin was inhibited to a lesser extent by aspirin, and aspirin did not prevent potentiation by epinephrine. These findings suggest that augmentation of the cytoplasmic free calcium level may be involved in the potentiation of platelet responses to agonists by epinephrine, and that metabolites of arachidonic acid make an important contribution to this action of epinephrine.
在加载了荧光钙指示剂喹啉-2的人血小板中，研究了肾上腺素与其他激动剂联合作用时细胞质游离钙的变化。在存在1mM细胞外钙的情况下，肾上腺素增强了血小板对胶原或凝血酶刺激的细胞质游离钙升高反应，且该反应被育亨宾抑制。在无细胞外钙时，凝血酶和胶原仅引起细胞质游离钙少量升高，且肾上腺素不能增强该反应。当细胞外存在钙时，高浓度肾上腺素单独作用可使血小板细胞质游离钙少量升高。阿司匹林抑制环氧合酶可显著降低血小板对胶原的钙反应，并几乎完全抑制肾上腺素的增强作用。阿司匹林对血小板对凝血酶的钙反应抑制作用较小，且不能阻止肾上腺素的增强作用。这些发现提示，细胞质游离钙水平的升高可能参与了肾上腺素对血小板激动剂反应的增强作用，且花生四烯酸代谢产物对肾上腺素的这一作用起重要作用。
