Powling M J, Hardisty R M
Department of Haematology and Oncology, Institute of Child Health, London, England.
Thromb Haemost. 1988 Apr 8;59(2):212-5.
In a medium containing 1 mM extracellular Ca2+ (Ca2+o), the prior addition of 0.5 microM adrenaline to quin 2-loaded human platelets increased both the rate and amplitude of the rise in cytosolic free Ca2+ (Ca2+i) in response to sub-threshold concentrations of thrombin and PAF and these effects were not prevented by blocking either fibrinogen binding and aggregation or cyclo-oxygenase. In the presence of 2 mM EGTA [( Ca2+o] less than 100 nM), the rate, but not the extent of rise of [Ca2+i] was enhanced by adrenaline, and this was also unaffected by blockade of cyclo-oxygenase. Addition of adrenaline 1 min after the other agonist in the presence of 1 mM Ca2+o resulted in aggregation without further elevation of [Ca2+i]. Adrenaline thus enhances both influx and intracellular mobilization of Ca2+ by a mechanism independent of both fibrinogen binding and thromboxane production, but these effects do not fully explain its potentiation of aggregation by other agonists.
在含有1 mM细胞外钙离子（Ca2+o）的培养基中，预先向负载喹2的人血小板添加0.5微摩尔肾上腺素，可增加对阈下浓度凝血酶和血小板激活因子（PAF）反应时胞质游离钙离子（Ca2+i）升高的速率和幅度，并且这些效应不会因阻断纤维蛋白原结合与聚集或环氧化酶而受到抑制。在存在2 mM乙二醇双（2-氨基乙醚）四乙酸（EGTA）（[Ca2+o]小于100 nM）的情况下，肾上腺素可增强[Ca2+i]升高的速率，但不增加其升高程度，并且这同样不受环氧化酶阻断的影响。在存在1 mM Ca2+o的情况下，在其他激动剂作用1分钟后添加肾上腺素会导致聚集，而[Ca2+i]不会进一步升高。因此，肾上腺素通过一种独立于纤维蛋白原结合和血栓素生成的机制增强钙离子的内流和细胞内动员，但这些效应并不能完全解释其对其他激动剂诱导聚集的增强作用。
