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Inhibition of human platelet aggregation and thromboxane B 2 production by melatonin. Correlation with plasma melatonin levels
Author(s) -
Vacas MarÍa I.,
Zar MarÍa de las M.,
Martinuzzo Marta,
Falcon Cristina,
Carreras Luis O.,
Cardinali Daniel P.
Publication year - 1991
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.1991.tb00468.x
Subject(s) - melatonin , medicine , endocrinology , platelet , arachidonic acid , thromboxane b2 , chemistry , thromboxane , biology , biochemistry , enzyme
Plasma melatonin concentrations and the effect of melatonin on arachidonic acid (AA)‐induced aggregation and thromboxane B 2 (TxB 2 ) production by platelet‐rich plasma (PRP) were examined in five normal male volunteers, sampled at 2 hr intervals from 21:30 to 09:30 hr. Peak plasma melatonin concentration was found at 03:30 hr. Inhibition by 10 −6 M melatonin of AA‐induced PRP aggregation was observed only in samples taken at 01:30 hr. Assessment of the inhibitory effect of 10 −9 –10 −6 M melatonin on AA‐induced TxB 2 production indicated that melatonin activity was greater at 01:30 h as compared to late night. Assessed as a global effect, the inhibitory activity of melatonin on PRP TxB 2 showed a maximum at 01:30 hr and minimal effects at 03:30 hr, at the time when plasma concentrations of melatonin were highest. These results indicate the existence of a nocturnal variation in sensitivity of human platelets to melatonin, with a peak that precedes the maximum in circulating melatonin levels.