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Circadian variation of fibrinolytic activity among Eskimos in Greenland
Insights
Eskimos exhibit distinct morning patterns in blood fibrinolytic activity, with faster increases in tissue-type plasminogen activator (t-PA) and quicker decreases in plasminogen activator inhibitor (PAI) compared to Caucasians.
Area of Science:
- Cardiovascular Research
- Hematology
- Chronobiology
Background:
- Circadian variation in blood fibrinolytic activity is linked to myocardial infarction onset in Caucasians.
- Depressed morning fibrinolytic activity correlates with increased cardiovascular events.
Purpose of the Study:
- To investigate the circadian variation of fibrinolytic activity in Eskimos.
- To compare fibrinolytic patterns between Eskimos and Caucasians.
- To explore the relationship between tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) in Eskimos.
Main Methods:
- Collected blood samples from 10 Eskimos over 24 hours at 4-hour intervals.
- Assessed the activity of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI).
- Analyzed circadian changes and correlations between t-PA and PAI.
Main Results:
- Significant circadian variations observed in both t-PA (p < 0.01) and PAI (p < 0.001) activity.
- Eskimos showed more rapid morning increases in t-PA and decreases in PAI compared to Caucasians.
- A strong negative correlation (r = -0.79, p < 0.0001) between PAI and t-PA was found, indicating PAI's regulatory role.
Conclusions:
- Eskimos display unique morning fibrinolytic patterns potentially influencing myocardial infarction prevalence.
- PAI plays a significant role in regulating t-PA activity in the blood.
- Standardization of blood sample collection is crucial for reliable fibrinolytic system studies in Eskimos.
Abstract:
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.