Circadian variation of fibrinolytic activity among Eskimos in Greenland.
Recent studies on circadian variation of blood fibrinolytic activity have suggested a relation between a depressed morning fibrinolytic activity and the frequent onset of myocardial infarction at that time in Caucasians. We have obtained blood samples from 10 Eskimos with an interval of 4 h during 24 h and studied the extrinsic tissue-type plasminogen activator-related fibrinolysis. We observed a significant change in the activity of tissue-type plasminogen activator (t-PA; p less than 0.01) and in the activity of plasminogen activator inhibitor (PAI; p less than 0.001) during 24 h. The activity of t-PA increased more rapidly and the activity of PAI decreased more rapidly during the morning hours in Eskimos compared to reported patterns in Caucasians. A significant negative correlation between PAI and t-PA (r = -0.79, p less than 0.0001) suggested that PAI contributes to the regulation of t-PA activity in the blood. Whether the observations are of importance for the low prevalence of myocardial infarction in Eskimos remains to be further studied. However, our observations demonstrate that it is of utmost importance to standardize the collection of blood samples in order to obtain reliable information on the fibrinolytic system in Eskimos.
Johansen
L G
LG
Gram
J
J
Kluft
C
C
Jespersen
J
J
D002940:Circadian Rhythm; D005260:Female; D005342:Fibrinolysis; D006116:Greenland; D006801:Humans; D004930:Inuit; D008297:Male; D010960:Plasminogen Activators / Q000097:blood
D010960:Plasminogen Activators