Lalau Keraly C, Kinlough-Rathbone R L, Mustard J F
Thromb Haemost. 1985 Jun 24;53(3):366-71.
The mechanisms involved in platelet aggregation induced by epinephrine are unclear. Although epinephrine does not aggregate washed rabbit platelets, platelets made refractory to ADP will aggregate in response to epinephrine in the presence of ADP. We have examined whether the mechanism(s) by which epinephrine induces aggregation of refractory platelets involves fibrinogen binding and Ca2+ association. With normal platelets, ADP causes aggregation, fibrinogen binding and Ca2+ association in a medium containing 0.2 mM 45Ca2+. After 3 min of incubation with ADP, fibrinogen dissociates from platelets, but 45Ca2+ does not. Epinephrine alone does not cause aggregation, fibrinogen binding or 45Ca2+ association. Platelets that are refractory to ADP do not aggregate and bind fibrinogen upon addition of ADP, but aggregate and bind fibrinogen in response to epinephrine, provided ADP is still present. These effects of epinephrine are mediated by the alpha-adrenergic receptor since they are blocked by phentolamine or verapamil and potentiated by propranolol. However, epinephrine-induced aggregation of platelets refractory to ADP does not involve further detectable increase in the amount of 45Ca2+ associated with the platelets.
肾上腺素诱导血小板聚集的机制尚不清楚。虽然肾上腺素不会使洗涤过的兔血小板聚集，但对ADP不敏感的血小板在有ADP存在的情况下会对肾上腺素发生聚集反应。我们研究了肾上腺素诱导不敏感血小板聚集的机制是否涉及纤维蛋白原结合和Ca2+结合。对于正常血小板，ADP在含有0.2 mM 45Ca2+的培养基中会引起聚集、纤维蛋白原结合和Ca2+结合。与ADP孵育3分钟后，纤维蛋白原从血小板上解离，但45Ca2+不会。单独的肾上腺素不会引起聚集、纤维蛋白原结合或45Ca2+结合。对ADP不敏感的血小板在加入ADP时不会聚集和结合纤维蛋白原，但在有ADP存在的情况下，会对肾上腺素发生聚集并结合纤维蛋白原。肾上腺素的这些作用是由α-肾上腺素能受体介导的，因为它们会被酚妥拉明或维拉帕米阻断，并被普萘洛尔增强。然而，肾上腺素诱导的对ADP不敏感的血小板聚集并不涉及与血小板结合的45Ca2+量的进一步可检测增加。
