Del Zar M M, Martinuzzo M, Cardinali D P, Carreras L O, Vacas M I
Departamento de Fisiología, Faculta de Medicina, Hospital de Clínicas José de San Martín, Universidad de Buenos Aires, Argentina.
Acta Endocrinol (Copenh). 1990 Oct;123(4):453-8. doi: 10.1530/acta.0.1230453.
The effect of the pineal hormone melatonin on adenosine diphosphate-induced human platelet aggregation and adenosine triphosphate release was assessed in platelet-rich plasma obtained from normal volunteers at 08.30 and 20.30 h. In 10(-7)-10(-5) mol/l concentrations melatonin inhibited ADP-induced platelet aggregation only in the evening (p less than 0.05). ADP-induced ATP release, an index of platelet secretory processes, showed a generally greater, dose-dependent inhibition after adding melatonin (10(-9)-10(-5)mol/l) at 20.30 h as compared with 08.30 h. The inhibitory activity of melatonin (10(-9)-10(-5) mol/l) on [3H]serotonin release elicited by thrombin in washed human platelets obtained from normal volunteers was dose-dependent; the effect was generally greater at 20.30 h. The activity of the potent platelet anti-aggregating agent prostacyclin did not exhibit diurnal differences with respect to impairing ADP-induced platelet-rich plasma aggregation. These results indicate the existence of a diurnal variation of sensitivity to melatonin in human platelets.
在上午8:30和晚上20:30从正常志愿者获取的富血小板血浆中，评估了松果体激素褪黑素对二磷酸腺苷诱导的人血小板聚集及三磷酸腺苷释放的影响。在10⁻⁷ - 10⁻⁵ mol/l浓度下，褪黑素仅在晚上抑制二磷酸腺苷诱导的血小板聚集（p < 0.05）。二磷酸腺苷诱导的三磷酸腺苷释放是血小板分泌过程的一个指标，与上午8:30相比，晚上20:30加入褪黑素（10⁻⁹ - 10⁻⁵ mol/l）后，通常表现出更大的、剂量依赖性抑制。褪黑素（10⁻⁹ - 10⁻⁵ mol/l）对从正常志愿者获取的洗涤人血小板中凝血酶引发的[³H]5-羟色胺释放的抑制活性呈剂量依赖性；该效应通常在晚上20:30更大。强效血小板抗聚集剂前列环素在损害二磷酸腺苷诱导的富血小板血浆聚集方面未表现出昼夜差异。这些结果表明人血小板对褪黑素的敏感性存在昼夜变化。
