Circadian variations of extrinsic fibrinolytic components in blood from eskimos

• Published in: Fibrinolysis
• Main Authors: Johansen, L. G., Gram, J., Kluft, C., Jespersen, J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1990
• Subjects: Circadian variation; Eskimos; Fibrinolysis; eskimo*
• Online Access: https://portal.findresearcher.sdu.dk/da/publications/2de5d797-da97-4b49-88a2-78614994a217; https://doi.org/10.1016/S0268-9499(05)80038-4

A depressed fibrinolytic activity and an increased platelet stickiness during the morning hours has been suggested to be related to the frequent onset of myocardial infarction at that time in caucasians. We have studied the fibrinolytic system in blood samples collected every 4h during 24h from Eskimos (n=10), reported to have low prevalence of myocardial infarction. We found no differences in plasminogen activator inhibitor (PAI)-1, determined in blood stabilised with citrate or in blood stabilised with citrate containing antiplatelet agents. Absence of platelet contribution to PAI-1 fluctuations was confirmed by platelet factor 4 (PF4) measurements. Tissue-type plasminogen activator (t-PA) activity (p<0.01), t-PA antigen (p<0.001), PAI activity (p<0.0001) and PAI-1 antigen (p<0.0002) fluctuated significantly during 24h, while the von Willebrand factor, a marker of the endothelial cell function, remained constant. The t-PA activity increased during the morning, remained elevated during the early afternoon and decreased during the evening and night, while t-PA antigen, PAI activity and PAI-1 antigen showed a reverse pattern. It is noted that Eskimos show a shift in the sinuous pattern of t-PA activity and PAI activity compared to reported results in caucasians. In particular, a more rapid increase in t-PA activity in the morning and a more rapid decrease of PAI activity and antigen might be a characteristic feature, which could add to the understanding of the low prevalence of myocardial infarction in Eskimos.