Daily variations of functional parameters and density distribution in human blood platelets.
Blood platelets play a critical role in the onset of myocardial infarction, which has been shown to have a circadian rhythmicity with a peak incidence in the morning. In an attempt to correlate platelet parameters with the outcome of cardiovascular diseases, we studied the daily (24-h) variation of the following platelet parameters: distribution pattern of functional heterogeneous platelet subpopulations; serotonin uptake; ketanserin binding; aggregation upon thrombin, serotonin, and ADP stimulation; and platelet count. Furthermore, we analyzed the tryptophan and serotonin concentrations in the blood samples. The percentage of less dense platelets, which represent the subpopulation with the highest preactivation, showed a rhythmicity period of 24 h and an acrophase at 21:18 h. The time course of intermediate and high density platelets was inverse to that of low density platelets. The serotonin uptake exhibited also a rhythmicity with a 24-h period. The acrophase was at 13:50 h. The aggregation curves were inverse to the ketanserin binding curves. The serotonin concentration exhibited a 12-h rhythmicity. The results obtained suggest that (a) changes in platelet activity are reflected by several parameters of platelet function that underlie daily variations; (b) the aggregation curves show a peak in the morning, with an additional peak in the afternoon; and (c) changes in the distribution pattern occur independently from variations in platelet functions like aggregation and serotonin binding.
Opper
C
C
Institut für Physiologische Chemie, Philipps-Universität, Marburg, Germany.
Weiner
N
N
Xü
F
F
Adam
W
W
Fruhstorfer
H
H
Wesemann
W
W
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000704:Analysis of Variance; D001792:Blood Platelets / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid; D002940:Circadian Rhythm; D006801:Humans; D007650:Ketanserin / Q000097:blood; D010974:Platelet Aggregation / Q000187:drug effects; D010976:Platelet Count; D012701:Serotonin / Q000097:blood / Q000494:pharmacology; D014364:Tryptophan / Q000097:blood
D012701:Serotonin; D014364:Tryptophan; D000255:Adenosine Triphosphate; D007650:Ketanserin